android 4.4 batteryservice 电池电量显示分析

转载地址：http://blog.csdn.net/daweibalang717/article/details/40615453

最近工作接触到这么的东西，这是我对整个电池管理方面Java 层的分析。如果想了解底层的话，请看我的博客：

android 4.4 电池电量管理底层分析(C\C++层) （http://blog.csdn.net/daweibalang717/article/details/41446993）
先贴一张类与类之间的关系图：

android开机过程中会加载系统BatteryService ,说一下电池电量相关的,本文主要讲述关于JAVA 层代码。文件路径：\frameworks\base\services\java\com\android\server\BatteryService.java   下面贴出源码。我把注释加上。个人理解，仅参考。

[java] view plain copy
/*

Copyright © 2006 The Android Open Source Project
Licensed under the Apache License, Version 2.0 (the “License”);
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an “AS IS” BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package com.android.server;

import android.os.BatteryStats;
import com.android.internal.app.IBatteryStats;
import com.android.server.am.BatteryStatsService;

import android.app.ActivityManagerNative;
import android.content.ContentResolver;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.BatteryManager;
import android.os.BatteryProperties;
import android.os.Binder;
import android.os.FileUtils;
import android.os.Handler;
import android.os.IBatteryPropertiesListener;
import android.os.IBatteryPropertiesRegistrar;
import android.os.IBinder;
import android.os.DropBoxManager;
import android.os.RemoteException;
import android.os.ServiceManager;
import android.os.SystemClock;
import android.os.UEventObserver;
import android.os.UserHandle;
import android.provider.Settings;
import android.util.EventLog;
import android.util.Slog;

import java.io.File;
import java.io.FileDescriptor;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.PrintWriter;

/**

BatteryService monitors the charging status, and charge level of the device
battery. When these values change this service broadcasts the new values
to all {@link android.content.BroadcastReceiver IntentReceivers} that are
watching the {@link android.content.Intent#ACTION_BATTERY_CHANGED
BATTERY_CHANGED} action.
The new values are stored in the Intent data and can be retrieved by
calling {@link android.content.Intent#getExtra Intent.getExtra} with the
following keys:
"scale" - int, the maximum value for the charge level
"level" - int, charge level, from 0 through "scale" inclusive
"status" - String, the current charging status.
"health" - String, the current battery health.
"present" - boolean, true if the battery is present
"icon-small" - int, suggested small icon to use for this state
"plugged" - int, 0 if the device is not plugged in; 1 if plugged
into an AC power adapter; 2 if plugged in via USB.
"voltage" - int, current battery voltage in millivolts
"temperature" - int, current battery temperature in tenths of
a degree Centigrade
"technology" - String, the type of battery installed, e.g. "Li-ion"
The battery service may be called by the power manager while holding its locks so
we take care to post all outcalls into the activity manager to a handler.
FIXME: Ideally the power manager would perform all of its calls into the battery
service asynchronously itself.

*/
public final class BatteryService extends Binder {
private static final String TAG = BatteryService.class.getSimpleName();

private static final boolean DEBUG = false;  private static final int BATTERY_SCALE = 100;    // battery capacity is a percentage  // Used locally for determining when to make a last ditch effort to log
// discharge stats before the device dies.
private int mCriticalBatteryLevel;  private static final int DUMP_MAX_LENGTH = 24 * 1024;
private static final String[] DUMPSYS_ARGS = new String[] { "--checkin", "--unplugged" };  private static final String DUMPSYS_DATA_PATH = "/data/system/";  // This should probably be exposed in the API, though it's not critical
private static final int BATTERY_PLUGGED_NONE = 0;  private final Context mContext;
private final IBatteryStats mBatteryStats;
private final Handler mHandler;  private final Object mLock = new Object();  private BatteryProperties mBatteryProps;
private boolean mBatteryLevelCritical;
private int mLastBatteryStatus;
private int mLastBatteryHealth;
private boolean mLastBatteryPresent;
private int mLastBatteryLevel;
private int mLastBatteryVoltage;
private int mLastBatteryTemperature;
private boolean mLastBatteryLevelCritical;  private int mInvalidCharger;
private int mLastInvalidCharger;  private int mLowBatteryWarningLevel;
private int mLowBatteryCloseWarningLevel;
private int mShutdownBatteryTemperature;  private int mPlugType;
private int mLastPlugType = -1; // Extra state so we can detect first run  private long mDischargeStartTime;
private int mDischargeStartLevel;  private boolean mUpdatesStopped;  private Led mLed;  private boolean mSentLowBatteryBroadcast = false;  private BatteryListener mBatteryPropertiesListener;
private IBatteryPropertiesRegistrar mBatteryPropertiesRegistrar;

//构造函数
public BatteryService(Context context, LightsService lights) {
mContext = context;
mHandler = new Handler(true /async/);
mLed = new Led(context, lights);//这个应该是指示灯，没实验
mBatteryStats = BatteryStatsService.getService();

//低电量临界值，这个数我看的源码版本值是4（在这个类里只是用来写日志）
mCriticalBatteryLevel = mContext.getResources().getInteger(
com.android.internal.R.integer.config_criticalBatteryWarningLevel);

//低电量告警值，值15，下面会根据这个变量发送低电量的广播Intent.ACTION_BATTERY_LOW（这个跟系统低电量提醒没关系，只是发出去了）
mLowBatteryWarningLevel = mContext.getResources().getInteger(
com.android.internal.R.integer.config_lowBatteryWarningLevel);

//电量告警取消值，值20 ，就是手机电量大于等于20的话发送Intent.ACTION_BATTERY_OKAY
mLowBatteryCloseWarningLevel = mContext.getResources().getInteger(
com.android.internal.R.integer.config_lowBatteryCloseWarningLevel);

//值是680 ，温度过高，超过这个值就发送广播，跳转到将要关机提醒。
mShutdownBatteryTemperature = mContext.getResources().getInteger(
com.android.internal.R.integer.config_shutdownBatteryTemperature);

    // watch for invalid charger messages if the invalid_charger switch exists  if (new File("/sys/devices/virtual/switch/invalid_charger/state").exists()) {  mInvalidChargerObserver.startObserving(  "DEVPATH=/devices/virtual/switch/invalid_charger");  }

//电池监听，这个应该是注册到底层去了。当底层电量改变会调用此监听。然后执行update(BatteryProperties props)；
mBatteryPropertiesListener = new BatteryListener();

    IBinder b = ServiceManager.getService("batterypropreg");  mBatteryPropertiesRegistrar = IBatteryPropertiesRegistrar.Stub.asInterface(b);  try {

//这里注册
mBatteryPropertiesRegistrar.registerListener(mBatteryPropertiesListener);
} catch (RemoteException e) {
// Should never happen.
}
}
//开机后先去看看是否没电了或者温度太高了。如果是，就关机提示（关机提示我等会介绍）。
void systemReady() {
// check our power situation now that it is safe to display the shutdown dialog.
synchronized (mLock) {
shutdownIfNoPowerLocked();
shutdownIfOverTempLocked();
}
}
//返回是否在充电，这个函数在PowerManagerService.java 中调用
/**
* Returns true if the device is plugged into any of the specified plug types.
*/
public boolean isPowered(int plugTypeSet) {
synchronized (mLock) {
return isPoweredLocked(plugTypeSet);
}
}
//就是这里，通过充电器类型判断是否充电
private boolean isPoweredLocked(int plugTypeSet) {
//我这英语小白猜着翻译下：就是开机后，电池状态不明了，那我们就认为就在充电，以便设备正常工作。
// assume we are powered if battery state is unknown so
// the “stay on while plugged in” option will work.
if (mBatteryProps.batteryStatus == BatteryManager.BATTERY_STATUS_UNKNOWN) {
return true;
}
//充电器
if ((plugTypeSet & BatteryManager.BATTERY_PLUGGED_AC) != 0 && mBatteryProps.chargerAcOnline) {
return true;
}
//USB，插电脑上充电
if ((plugTypeSet & BatteryManager.BATTERY_PLUGGED_USB) != 0 && mBatteryProps.chargerUsbOnline) {
return true;
}
//电源是无线的。（我没见过…）
if ((plugTypeSet & BatteryManager.BATTERY_PLUGGED_WIRELESS) != 0 && mBatteryProps.chargerWirelessOnline) {
return true;
}
return false;
}

/** * Returns the current plug type. */

//充电器类型
public int getPlugType() {
synchronized (mLock) {
return mPlugType;
}
}

/** * Returns battery level as a percentage. */

//电池属性：电量等级（0-100）
public int getBatteryLevel() {
synchronized (mLock) {
return mBatteryProps.batteryLevel;
}
}

/** * Returns true if battery level is below the first warning threshold. */

//低电量
public boolean isBatteryLow() {
synchronized (mLock) {
return mBatteryProps.batteryPresent && mBatteryProps.batteryLevel <= mLowBatteryWarningLevel;
}
}

/** * Returns a non-zero value if an  unsupported charger is attached. */

//不支持的充电器类型
public int getInvalidCharger() {
synchronized (mLock) {
return mInvalidCharger;
}
}

//这里就是没电了，要关机的提示。
private void shutdownIfNoPowerLocked() {
// shut down gracefully if our battery is critically low and we are not powered.
// wait until the system has booted before attempting to display the shutdown dialog.
if (mBatteryProps.batteryLevel == 0 && (mBatteryProps.batteryStatus == BatteryManager.BATTERY_STATUS_DISCHARGING)) {
mHandler.post(new Runnable() {
@Override
public void run() {
if (ActivityManagerNative.isSystemReady()) {
Intent intent = new Intent(“android.intent.action.ACTION_REQUEST_SHUTDOWN_LOWBATTERY”);//ACTION_REQUEST_SHUTDOWN
intent.putExtra(Intent.EXTRA_KEY_CONFIRM, false);
intent.putExtra(“cant_be_cancel_by_button”, true);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
mContext.startActivityAsUser(intent, UserHandle.CURRENT);
}
}
});
}
}

//温度过高，关机提示（个人感觉这里有问题，温度过高为啥子跳转到没电关机提示界面）
private void shutdownIfOverTempLocked() {
// shut down gracefully if temperature is too high (> 68.0C by default)
// wait until the system has booted before attempting to display the
// shutdown dialog.
if (mBatteryProps.batteryTemperature > mShutdownBatteryTemperature) {
mHandler.post(new Runnable() {
@Override
public void run() {
if (ActivityManagerNative.isSystemReady()) {
Intent intent = new Intent(“android.intent.action.ACTION_REQUEST_SHUTDOWN_LOWBATTERY”);//ACTION_REQUEST_SHUTDOWN
intent.putExtra(Intent.EXTRA_KEY_CONFIRM, false);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
mContext.startActivityAsUser(intent, UserHandle.CURRENT);
}
}
});
}
}
//这个方法就是被JNI回调的。用来更新上层状态的方法。
private void update(BatteryProperties props) {
synchronized (mLock) {
if (!mUpdatesStopped) {
mBatteryProps = props;
// Process the new values.
processValuesLocked();
}
}
}
//嗯。这个就是最主要的方法了。
private void processValuesLocked() {
boolean logOutlier = false;
long dischargeDuration = 0;

    mBatteryLevelCritical = (mBatteryProps.batteryLevel <= mCriticalBatteryLevel);

//充电器类型
if (mBatteryProps.chargerAcOnline) {
mPlugType = BatteryManager.BATTERY_PLUGGED_AC;
} else if (mBatteryProps.chargerUsbOnline) {
mPlugType = BatteryManager.BATTERY_PLUGGED_USB;
} else if (mBatteryProps.chargerWirelessOnline) {
mPlugType = BatteryManager.BATTERY_PLUGGED_WIRELESS;
} else {
mPlugType = BATTERY_PLUGGED_NONE;
}

    if (DEBUG) {//日志，略过  Slog.d(TAG, "Processing new values: "  + "chargerAcOnline=" + mBatteryProps.chargerAcOnline  + ", chargerUsbOnline=" + mBatteryProps.chargerUsbOnline  + ", chargerWirelessOnline=" + mBatteryProps.chargerWirelessOnline  + ", batteryStatus=" + mBatteryProps.batteryStatus  + ", batteryHealth=" + mBatteryProps.batteryHealth  + ", batteryPresent=" + mBatteryProps.batteryPresent  + ", batteryLevel=" + mBatteryProps.batteryLevel  + ", batteryTechnology=" + mBatteryProps.batteryTechnology  + ", batteryVoltage=" + mBatteryProps.batteryVoltage  + ", batteryCurrentNow=" + mBatteryProps.batteryCurrentNow  + ", batteryChargeCounter=" + mBatteryProps.batteryChargeCounter  + ", batteryTemperature=" + mBatteryProps.batteryTemperature  + ", mBatteryLevelCritical=" + mBatteryLevelCritical  + ", mPlugType=" + mPlugType);  }  // Let the battery stats keep track of the current level.  try {

//把电池属性放到状态里面
mBatteryStats.setBatteryState(mBatteryProps.batteryStatus, mBatteryProps.batteryHealth,
mPlugType, mBatteryProps.batteryLevel, mBatteryProps.batteryTemperature,
mBatteryProps.batteryVoltage);
} catch (RemoteException e) {
// Should never happen.
}
//没电了
shutdownIfNoPowerLocked();
//温度过高了
shutdownIfOverTempLocked();

    if (mBatteryProps.batteryStatus != mLastBatteryStatus ||  mBatteryProps.batteryHealth != mLastBatteryHealth ||  mBatteryProps.batteryPresent != mLastBatteryPresent ||  mBatteryProps.batteryLevel != mLastBatteryLevel ||  mPlugType != mLastPlugType ||  mBatteryProps.batteryVoltage != mLastBatteryVoltage ||  mBatteryProps.batteryTemperature != mLastBatteryTemperature ||  mInvalidCharger != mLastInvalidCharger) {  if (mPlugType != mLastPlugType) {//当前充电器类型与上次的不一样

//并且上次充电器类型是no one ，那就可以知道，现在是插上充电器了。
if (mLastPlugType == BATTERY_PLUGGED_NONE) {
// discharging -> charging

                // There's no value in this data unless we've discharged at least once and the  // battery level has changed; so don't log until it does.  if (mDischargeStartTime != 0 && mDischargeStartLevel != mBatteryProps.batteryLevel) {  dischargeDuration = SystemClock.elapsedRealtime() - mDischargeStartTime;  logOutlier = true;  EventLog.writeEvent(EventLogTags.BATTERY_DISCHARGE, dischargeDuration,  mDischargeStartLevel, mBatteryProps.batteryLevel);  // make sure we see a discharge event before logging again  mDischargeStartTime = 0;  }

//并且本次充电器类型是no one ，那就可以知道，现在是拔掉充电器了。
} else if (mPlugType == BATTERY_PLUGGED_NONE) {
// charging -> discharging or we just powered up
mDischargeStartTime = SystemClock.elapsedRealtime();
mDischargeStartLevel = mBatteryProps.batteryLevel;
}
}
if (mBatteryProps.batteryStatus != mLastBatteryStatus ||//写日志，略过
mBatteryProps.batteryHealth != mLastBatteryHealth ||
mBatteryProps.batteryPresent != mLastBatteryPresent ||
mPlugType != mLastPlugType) {
EventLog.writeEvent(EventLogTags.BATTERY_STATUS,
mBatteryProps.batteryStatus, mBatteryProps.batteryHealth, mBatteryProps.batteryPresent ? 1 : 0,
mPlugType, mBatteryProps.batteryTechnology);
}
if (mBatteryProps.batteryLevel != mLastBatteryLevel) {
// Don’t do this just from voltage or temperature changes, that is
// too noisy.
EventLog.writeEvent(EventLogTags.BATTERY_LEVEL,
mBatteryProps.batteryLevel, mBatteryProps.batteryVoltage, mBatteryProps.batteryTemperature);
}
if (mBatteryLevelCritical && !mLastBatteryLevelCritical &&
mPlugType == BATTERY_PLUGGED_NONE) {
// We want to make sure we log discharge cycle outliers
// if the battery is about to die.
dischargeDuration = SystemClock.elapsedRealtime() - mDischargeStartTime;
logOutlier = true;
}
//本次调用，当前的充电状态
final boolean plugged = mPlugType != BATTERY_PLUGGED_NONE;
//本次调用，上次调用的充电状态
final boolean oldPlugged = mLastPlugType != BATTERY_PLUGGED_NONE;

        /* The ACTION_BATTERY_LOW broadcast is sent in these situations: * - is just un-plugged (previously was plugged) and battery level is *   less than or equal to WARNING, or * - is not plugged and battery level falls to WARNING boundary *   (becomes <= mLowBatteryWarningLevel). */

//用于发送低电量广播的判断
final boolean sendBatteryLow = !plugged//（按sendBatteryLow = true 来说）当前没有充电
&& mBatteryProps.batteryStatus != BatteryManager.BATTERY_STATUS_UNKNOWN//充电状态不是UNKNOWN
&& mBatteryProps.batteryLevel <= mLowBatteryWarningLevel//当前电量小于告警值 15
&& (oldPlugged || mLastBatteryLevel > mLowBatteryWarningLevel);//上次状态是充电或者上次电量等级大于告警值 15

        sendIntentLocked();//发送电池电量改变的广播Intent.ACTION_BATTERY_CHANGED  // Separate broadcast is sent for power connected / not connected  // since the standard intent will not wake any applications and some  // applications may want to have smart behavior based on this.  if (mPlugType != 0 && mLastPlugType == 0) {//插上充电器了  mHandler.post(new Runnable() {  @Override  public void run() {  Intent statusIntent = new Intent(Intent.ACTION_POWER_CONNECTED);  statusIntent.setFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT);  mContext.sendBroadcastAsUser(statusIntent, UserHandle.ALL);  }  });  }  else if (mPlugType == 0 && mLastPlugType != 0) {//断开充电器了  mHandler.post(new Runnable() {  @Override  public void run() {  Intent statusIntent = new Intent(Intent.ACTION_POWER_DISCONNECTED);  statusIntent.setFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT);  mContext.sendBroadcastAsUser(statusIntent, UserHandle.ALL);  }  });  }

//发送低电量提醒（这个跟系统低电量提醒没关系，只是发出去了）
if (sendBatteryLow) {
mSentLowBatteryBroadcast = true;
mHandler.post(new Runnable() {
@Override
public void run() {
Intent statusIntent = new Intent(Intent.ACTION_BATTERY_LOW);
statusIntent.setFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT);
mContext.sendBroadcastAsUser(statusIntent, UserHandle.ALL);
}
});
} else if (mSentLowBatteryBroadcast && mLastBatteryLevel >= mLowBatteryCloseWarningLevel) {//电量超过20了。电池状态OK了
mSentLowBatteryBroadcast = false;
mHandler.post(new Runnable() {
@Override
public void run() {
Intent statusIntent = new Intent(Intent.ACTION_BATTERY_OKAY);
statusIntent.setFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT);
mContext.sendBroadcastAsUser(statusIntent, UserHandle.ALL);
}
});
}

        // Update the battery LED  mLed.updateLightsLocked();  // This needs to be done after sendIntent() so that we get the lastest battery stats.  if (logOutlier && dischargeDuration != 0) {  logOutlierLocked(dischargeDuration);  }  mLastBatteryStatus = mBatteryProps.batteryStatus;  mLastBatteryHealth = mBatteryProps.batteryHealth;  mLastBatteryPresent = mBatteryProps.batteryPresent;  mLastBatteryLevel = mBatteryProps.batteryLevel;  mLastPlugType = mPlugType;  mLastBatteryVoltage = mBatteryProps.batteryVoltage;  mLastBatteryTemperature = mBatteryProps.batteryTemperature;  mLastBatteryLevelCritical = mBatteryLevelCritical;  mLastInvalidCharger = mInvalidCharger;  }
}

//电池电量改变，把属性发出去（系统低电量提醒接收的是这个广播）
private void sendIntentLocked() {
// Pack up the values and broadcast them to everyone
final Intent intent = new Intent(Intent.ACTION_BATTERY_CHANGED);
intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY
| Intent.FLAG_RECEIVER_REPLACE_PENDING);

    int icon = getIconLocked(mBatteryProps.batteryLevel);  intent.putExtra(BatteryManager.EXTRA_STATUS, mBatteryProps.batteryStatus);  intent.putExtra(BatteryManager.EXTRA_HEALTH, mBatteryProps.batteryHealth);  intent.putExtra(BatteryManager.EXTRA_PRESENT, mBatteryProps.batteryPresent);  intent.putExtra(BatteryManager.EXTRA_LEVEL, mBatteryProps.batteryLevel);  intent.putExtra(BatteryManager.EXTRA_SCALE, BATTERY_SCALE);  intent.putExtra(BatteryManager.EXTRA_ICON_SMALL, icon);  intent.putExtra(BatteryManager.EXTRA_PLUGGED, mPlugType);  intent.putExtra(BatteryManager.EXTRA_VOLTAGE, mBatteryProps.batteryVoltage);  intent.putExtra(BatteryManager.EXTRA_TEMPERATURE, mBatteryProps.batteryTemperature);  intent.putExtra(BatteryManager.EXTRA_TECHNOLOGY, mBatteryProps.batteryTechnology);  intent.putExtra(BatteryManager.EXTRA_INVALID_CHARGER, mInvalidCharger);  if (DEBUG) {  Slog.d(TAG, "Sending ACTION_BATTERY_CHANGED.  level:" + mBatteryProps.batteryLevel +  ", scale:" + BATTERY_SCALE + ", status:" + mBatteryProps.batteryStatus +  ", health:" + mBatteryProps.batteryHealth +  ", present:" + mBatteryProps.batteryPresent +  ", voltage: " + mBatteryProps.batteryVoltage +  ", temperature: " + mBatteryProps.batteryTemperature +  ", technology: " + mBatteryProps.batteryTechnology +  ", AC powered:" + mBatteryProps.chargerAcOnline + ", USB powered:" + mBatteryProps.chargerUsbOnline +  ", Wireless powered:" + mBatteryProps.chargerWirelessOnline +  ", icon:" + icon  + ", invalid charger:" + mInvalidCharger);  }  mHandler.post(new Runnable() {  @Override  public void run() {  ActivityManagerNative.broadcastStickyIntent(intent, null, UserHandle.USER_ALL);  }  });
}  private void logBatteryStatsLocked() {  IBinder batteryInfoService = ServiceManager.getService(BatteryStats.SERVICE_NAME);  if (batteryInfoService == null) return;  DropBoxManager db = (DropBoxManager) mContext.getSystemService(Context.DROPBOX_SERVICE);  if (db == null || !db.isTagEnabled("BATTERY_DISCHARGE_INFO")) return;  File dumpFile = null;  FileOutputStream dumpStream = null;  try {  // dump the service to a file  dumpFile = new File(DUMPSYS_DATA_PATH + BatteryStats.SERVICE_NAME + ".dump");  dumpStream = new FileOutputStream(dumpFile);  batteryInfoService.dump(dumpStream.getFD(), DUMPSYS_ARGS);  FileUtils.sync(dumpStream);  // add dump file to drop box  db.addFile("BATTERY_DISCHARGE_INFO", dumpFile, DropBoxManager.IS_TEXT);  } catch (RemoteException e) {  Slog.e(TAG, "failed to dump battery service", e);  } catch (IOException e) {  Slog.e(TAG, "failed to write dumpsys file", e);  } finally {  // make sure we clean up  if (dumpStream != null) {  try {  dumpStream.close();  } catch (IOException e) {  Slog.e(TAG, "failed to close dumpsys output stream");  }  }  if (dumpFile != null && !dumpFile.delete()) {  Slog.e(TAG, "failed to delete temporary dumpsys file: "  + dumpFile.getAbsolutePath());  }  }
}  private void logOutlierLocked(long duration) {  ContentResolver cr = mContext.getContentResolver();  String dischargeThresholdString = Settings.Global.getString(cr,  Settings.Global.BATTERY_DISCHARGE_THRESHOLD);  String durationThresholdString = Settings.Global.getString(cr,  Settings.Global.BATTERY_DISCHARGE_DURATION_THRESHOLD);  if (dischargeThresholdString != null && durationThresholdString != null) {  try {  long durationThreshold = Long.parseLong(durationThresholdString);  int dischargeThreshold = Integer.parseInt(dischargeThresholdString);  if (duration <= durationThreshold &&  mDischargeStartLevel - mBatteryProps.batteryLevel >= dischargeThreshold) {  // If the discharge cycle is bad enough we want to know about it.  logBatteryStatsLocked();  }  if (DEBUG) Slog.v(TAG, "duration threshold: " + durationThreshold +  " discharge threshold: " + dischargeThreshold);  if (DEBUG) Slog.v(TAG, "duration: " + duration + " discharge: " +  (mDischargeStartLevel - mBatteryProps.batteryLevel));  } catch (NumberFormatException e) {  Slog.e(TAG, "Invalid DischargeThresholds GService string: " +  durationThresholdString + " or " + dischargeThresholdString);  return;  }  }
}  private int getIconLocked(int level) {  if (mBatteryProps.batteryStatus == BatteryManager.BATTERY_STATUS_CHARGING) {  return com.android.internal.R.drawable.stat_sys_battery_charge;  } else if (mBatteryProps.batteryStatus == BatteryManager.BATTERY_STATUS_DISCHARGING) {  return com.android.internal.R.drawable.stat_sys_battery;  } else if (mBatteryProps.batteryStatus == BatteryManager.BATTERY_STATUS_NOT_CHARGING  || mBatteryProps.batteryStatus == BatteryManager.BATTERY_STATUS_FULL) {  if (isPoweredLocked(BatteryManager.BATTERY_PLUGGED_ANY)  && mBatteryProps.batteryLevel >= 100) {  return com.android.internal.R.drawable.stat_sys_battery_charge;  } else {  return com.android.internal.R.drawable.stat_sys_battery;  }  } else {  return com.android.internal.R.drawable.stat_sys_battery_unknown;  }
}  @Override
protected void dump(FileDescriptor fd, PrintWriter pw, String[] args) {  if (mContext.checkCallingOrSelfPermission(android.Manifest.permission.DUMP)  != PackageManager.PERMISSION_GRANTED) {  pw.println("Permission Denial: can't dump Battery service from from pid="  + Binder.getCallingPid()  + ", uid=" + Binder.getCallingUid());  return;  }  synchronized (mLock) {  if (args == null || args.length == 0 || "-a".equals(args[0])) {  pw.println("Current Battery Service state:");  if (mUpdatesStopped) {  pw.println("  (UPDATES STOPPED -- use 'reset' to restart)");  }  pw.println("  AC powered: " + mBatteryProps.chargerAcOnline);  pw.println("  USB powered: " + mBatteryProps.chargerUsbOnline);  pw.println("  Wireless powered: " + mBatteryProps.chargerWirelessOnline);  pw.println("  status: " + mBatteryProps.batteryStatus);  pw.println("  health: " + mBatteryProps.batteryHealth);  pw.println("  present: " + mBatteryProps.batteryPresent);  pw.println("  level: " + mBatteryProps.batteryLevel);  pw.println("  scale: " + BATTERY_SCALE);  pw.println("  voltage: " + mBatteryProps.batteryVoltage);  if (mBatteryProps.batteryCurrentNow != Integer.MIN_VALUE) {  pw.println("  current now: " + mBatteryProps.batteryCurrentNow);  }  if (mBatteryProps.batteryChargeCounter != Integer.MIN_VALUE) {  pw.println("  charge counter: " + mBatteryProps.batteryChargeCounter);  }  pw.println("  temperature: " + mBatteryProps.batteryTemperature);  pw.println("  technology: " + mBatteryProps.batteryTechnology);  } else if (args.length == 3 && "set".equals(args[0])) {  String key = args[1];  String value = args[2];  try {  boolean update = true;  if ("ac".equals(key)) {  mBatteryProps.chargerAcOnline = Integer.parseInt(value) != 0;  } else if ("usb".equals(key)) {  mBatteryProps.chargerUsbOnline = Integer.parseInt(value) != 0;  } else if ("wireless".equals(key)) {  mBatteryProps.chargerWirelessOnline = Integer.parseInt(value) != 0;  } else if ("status".equals(key)) {  mBatteryProps.batteryStatus = Integer.parseInt(value);  } else if ("level".equals(key)) {  mBatteryProps.batteryLevel = Integer.parseInt(value);  } else if ("invalid".equals(key)) {  mInvalidCharger = Integer.parseInt(value);  } else {  pw.println("Unknown set option: " + key);  update = false;  }  if (update) {  long ident = Binder.clearCallingIdentity();  try {  mUpdatesStopped = true;  processValuesLocked();  } finally {  Binder.restoreCallingIdentity(ident);  }  }  } catch (NumberFormatException ex) {  pw.println("Bad value: " + value);  }  } else if (args.length == 1 && "reset".equals(args[0])) {  long ident = Binder.clearCallingIdentity();  try {  mUpdatesStopped = false;  } finally {  Binder.restoreCallingIdentity(ident);  }  } else {  pw.println("Dump current battery state, or:");  pw.println("  set ac|usb|wireless|status|level|invalid <value>");  pw.println("  reset");  }  }
}  private final UEventObserver mInvalidChargerObserver = new UEventObserver() {  @Override  public void onUEvent(UEventObserver.UEvent event) {  final int invalidCharger = "1".equals(event.get("SWITCH_STATE")) ? 1 : 0;  synchronized (mLock) {  if (mInvalidCharger != invalidCharger) {  mInvalidCharger = invalidCharger;  }  }  }
};  private final class Led {  private final LightsService.Light mBatteryLight;  private final int mBatteryLowARGB;  private final int mBatteryMediumARGB;  private final int mBatteryFullARGB;  private final int mBatteryLedOn;  private final int mBatteryLedOff;  public Led(Context context, LightsService lights) {  mBatteryLight = lights.getLight(LightsService.LIGHT_ID_BATTERY);  mBatteryLowARGB = context.getResources().getInteger(  com.android.internal.R.integer.config_notificationsBatteryLowARGB);  mBatteryMediumARGB = context.getResources().getInteger(  com.android.internal.R.integer.config_notificationsBatteryMediumARGB);  mBatteryFullARGB = context.getResources().getInteger(  com.android.internal.R.integer.config_notificationsBatteryFullARGB);  mBatteryLedOn = context.getResources().getInteger(  com.android.internal.R.integer.config_notificationsBatteryLedOn);  mBatteryLedOff = context.getResources().getInteger(  com.android.internal.R.integer.config_notificationsBatteryLedOff);  }  /** * Synchronize on BatteryService. */  public void updateLightsLocked() {  final int level = mBatteryProps.batteryLevel;  final int status = mBatteryProps.batteryStatus;  if (level < mLowBatteryWarningLevel) {  if (status == BatteryManager.BATTERY_STATUS_CHARGING) {  // Solid red when battery is charging  mBatteryLight.setColor(mBatteryLowARGB);  } else {  // Flash red when battery is low and not charging  mBatteryLight.setFlashing(mBatteryLowARGB, LightsService.LIGHT_FLASH_TIMED,  mBatteryLedOn, mBatteryLedOff);  }  } else if (status == BatteryManager.BATTERY_STATUS_CHARGING  || status == BatteryManager.BATTERY_STATUS_FULL) {  if (status == BatteryManager.BATTERY_STATUS_FULL || level >= 90) {  // Solid green when full or charging and nearly full  mBatteryLight.setColor(mBatteryFullARGB);  } else {  // Solid orange when charging and halfway full  mBatteryLight.setColor(mBatteryMediumARGB);  }  } else {  // No lights if not charging and not low  mBatteryLight.turnOff();  }  }
}  private final class BatteryListener extends IBatteryPropertiesListener.Stub {  public void batteryPropertiesChanged(BatteryProperties props) {  BatteryService.this.update(props);  }
}

}
/*

Copyright © 2006 The Android Open Source Project
Licensed under the Apache License, Version 2.0 (the “License”);
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an “AS IS” BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package com.android.server;

import android.os.BatteryStats;
import com.android.internal.app.IBatteryStats;
import com.android.server.am.BatteryStatsService;

import java.io.File;
import java.io.FileDescriptor;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.PrintWriter;

/**

BatteryService monitors the charging status, and charge level of the device
battery. When these values change this service broadcasts the new values
to all {@link android.content.BroadcastReceiver IntentReceivers} that are
watching the {@link android.content.Intent#ACTION_BATTERY_CHANGED
BATTERY_CHANGED} action.
The new values are stored in the Intent data and can be retrieved by
calling {@link android.content.Intent#getExtra Intent.getExtra} with the
following keys:
"scale" - int, the maximum value for the charge level
"level" - int, charge level, from 0 through "scale" inclusive
"status" - String, the current charging status.
"health" - String, the current battery health.
"present" - boolean, true if the battery is present
"icon-small" - int, suggested small icon to use for this state
"plugged" - int, 0 if the device is not plugged in; 1 if plugged
into an AC power adapter; 2 if plugged in via USB.
"voltage" - int, current battery voltage in millivolts
"temperature" - int, current battery temperature in tenths of
a degree Centigrade
"technology" - String, the type of battery installed, e.g. "Li-ion"
The battery service may be called by the power manager while holding its locks so
we take care to post all outcalls into the activity manager to a handler.
FIXME: Ideally the power manager would perform all of its calls into the battery
service asynchronously itself.

*/
public final class BatteryService extends Binder {
private static final String TAG = BatteryService.class.getSimpleName();

private static final boolean DEBUG = false;private static final int BATTERY_SCALE = 100;    // battery capacity is a percentage// Used locally for determining when to make a last ditch effort to log
// discharge stats before the device dies.
private int mCriticalBatteryLevel;private static final int DUMP_MAX_LENGTH = 24 * 1024;
private static final String[] DUMPSYS_ARGS = new String[] { "--checkin", "--unplugged" };private static final String DUMPSYS_DATA_PATH = "/data/system/";// This should probably be exposed in the API, though it's not critical
private static final int BATTERY_PLUGGED_NONE = 0;private final Context mContext;
private final IBatteryStats mBatteryStats;
private final Handler mHandler;private final Object mLock = new Object();private BatteryProperties mBatteryProps;
private boolean mBatteryLevelCritical;
private int mLastBatteryStatus;
private int mLastBatteryHealth;
private boolean mLastBatteryPresent;
private int mLastBatteryLevel;
private int mLastBatteryVoltage;
private int mLastBatteryTemperature;
private boolean mLastBatteryLevelCritical;private int mInvalidCharger;
private int mLastInvalidCharger;private int mLowBatteryWarningLevel;
private int mLowBatteryCloseWarningLevel;
private int mShutdownBatteryTemperature;private int mPlugType;
private int mLastPlugType = -1; // Extra state so we can detect first runprivate long mDischargeStartTime;
private int mDischargeStartLevel;private boolean mUpdatesStopped;private Led mLed;private boolean mSentLowBatteryBroadcast = false;private BatteryListener mBatteryPropertiesListener;
private IBatteryPropertiesRegistrar mBatteryPropertiesRegistrar;

    // watch for invalid charger messages if the invalid_charger switch existsif (new File("/sys/devices/virtual/switch/invalid_charger/state").exists()) {mInvalidChargerObserver.startObserving("DEVPATH=/devices/virtual/switch/invalid_charger");}

//电池监听，这个应该是注册到底层去了。当底层电量改变会调用此监听。然后执行update(BatteryProperties props)；
mBatteryPropertiesListener = new BatteryListener();

    IBinder b = ServiceManager.getService("batterypropreg");mBatteryPropertiesRegistrar = IBatteryPropertiesRegistrar.Stub.asInterface(b);try {

/*** Returns the current plug type.*/

//充电器类型
public int getPlugType() {
synchronized (mLock) {
return mPlugType;
}
}

/*** Returns battery level as a percentage.*/

//电池属性：电量等级（0-100）
public int getBatteryLevel() {
synchronized (mLock) {
return mBatteryProps.batteryLevel;
}
}

/*** Returns true if battery level is below the first warning threshold.*/

//低电量
public boolean isBatteryLow() {
synchronized (mLock) {
return mBatteryProps.batteryPresent && mBatteryProps.batteryLevel <= mLowBatteryWarningLevel;
}
}

/*** Returns a non-zero value if an  unsupported charger is attached.*/

//不支持的充电器类型
public int getInvalidCharger() {
synchronized (mLock) {
return mInvalidCharger;
}
}

    mBatteryLevelCritical = (mBatteryProps.batteryLevel <= mCriticalBatteryLevel);

    if (DEBUG) {//日志，略过Slog.d(TAG, "Processing new values: "+ "chargerAcOnline=" + mBatteryProps.chargerAcOnline+ ", chargerUsbOnline=" + mBatteryProps.chargerUsbOnline+ ", chargerWirelessOnline=" + mBatteryProps.chargerWirelessOnline+ ", batteryStatus=" + mBatteryProps.batteryStatus+ ", batteryHealth=" + mBatteryProps.batteryHealth+ ", batteryPresent=" + mBatteryProps.batteryPresent+ ", batteryLevel=" + mBatteryProps.batteryLevel+ ", batteryTechnology=" + mBatteryProps.batteryTechnology+ ", batteryVoltage=" + mBatteryProps.batteryVoltage+ ", batteryCurrentNow=" + mBatteryProps.batteryCurrentNow+ ", batteryChargeCounter=" + mBatteryProps.batteryChargeCounter+ ", batteryTemperature=" + mBatteryProps.batteryTemperature+ ", mBatteryLevelCritical=" + mBatteryLevelCritical+ ", mPlugType=" + mPlugType);}// Let the battery stats keep track of the current level.try {

    if (mBatteryProps.batteryStatus != mLastBatteryStatus ||mBatteryProps.batteryHealth != mLastBatteryHealth ||mBatteryProps.batteryPresent != mLastBatteryPresent ||mBatteryProps.batteryLevel != mLastBatteryLevel ||mPlugType != mLastPlugType ||mBatteryProps.batteryVoltage != mLastBatteryVoltage ||mBatteryProps.batteryTemperature != mLastBatteryTemperature ||mInvalidCharger != mLastInvalidCharger) {if (mPlugType != mLastPlugType) {//当前充电器类型与上次的不一样

//并且上次充电器类型是no one ，那就可以知道，现在是插上充电器了。
if (mLastPlugType == BATTERY_PLUGGED_NONE) {
// discharging -> charging

                // There's no value in this data unless we've discharged at least once and the// battery level has changed; so don't log until it does.if (mDischargeStartTime != 0 && mDischargeStartLevel != mBatteryProps.batteryLevel) {dischargeDuration = SystemClock.elapsedRealtime() - mDischargeStartTime;logOutlier = true;EventLog.writeEvent(EventLogTags.BATTERY_DISCHARGE, dischargeDuration,mDischargeStartLevel, mBatteryProps.batteryLevel);// make sure we see a discharge event before logging againmDischargeStartTime = 0;}

        /* The ACTION_BATTERY_LOW broadcast is sent in these situations:* - is just un-plugged (previously was plugged) and battery level is*   less than or equal to WARNING, or* - is not plugged and battery level falls to WARNING boundary*   (becomes <= mLowBatteryWarningLevel).*/

        sendIntentLocked();//发送电池电量改变的广播Intent.ACTION_BATTERY_CHANGED// Separate broadcast is sent for power connected / not connected// since the standard intent will not wake any applications and some// applications may want to have smart behavior based on this.if (mPlugType != 0 && mLastPlugType == 0) {//插上充电器了mHandler.post(new Runnable() {@Overridepublic void run() {Intent statusIntent = new Intent(Intent.ACTION_POWER_CONNECTED);statusIntent.setFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT);mContext.sendBroadcastAsUser(statusIntent, UserHandle.ALL);}});}else if (mPlugType == 0 && mLastPlugType != 0) {//断开充电器了mHandler.post(new Runnable() {@Overridepublic void run() {Intent statusIntent = new Intent(Intent.ACTION_POWER_DISCONNECTED);statusIntent.setFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT);mContext.sendBroadcastAsUser(statusIntent, UserHandle.ALL);}});}

        // Update the battery LEDmLed.updateLightsLocked();// This needs to be done after sendIntent() so that we get the lastest battery stats.if (logOutlier && dischargeDuration != 0) {logOutlierLocked(dischargeDuration);}mLastBatteryStatus = mBatteryProps.batteryStatus;mLastBatteryHealth = mBatteryProps.batteryHealth;mLastBatteryPresent = mBatteryProps.batteryPresent;mLastBatteryLevel = mBatteryProps.batteryLevel;mLastPlugType = mPlugType;mLastBatteryVoltage = mBatteryProps.batteryVoltage;mLastBatteryTemperature = mBatteryProps.batteryTemperature;mLastBatteryLevelCritical = mBatteryLevelCritical;mLastInvalidCharger = mInvalidCharger;}
}

    int icon = getIconLocked(mBatteryProps.batteryLevel);intent.putExtra(BatteryManager.EXTRA_STATUS, mBatteryProps.batteryStatus);intent.putExtra(BatteryManager.EXTRA_HEALTH, mBatteryProps.batteryHealth);intent.putExtra(BatteryManager.EXTRA_PRESENT, mBatteryProps.batteryPresent);intent.putExtra(BatteryManager.EXTRA_LEVEL, mBatteryProps.batteryLevel);intent.putExtra(BatteryManager.EXTRA_SCALE, BATTERY_SCALE);intent.putExtra(BatteryManager.EXTRA_ICON_SMALL, icon);intent.putExtra(BatteryManager.EXTRA_PLUGGED, mPlugType);intent.putExtra(BatteryManager.EXTRA_VOLTAGE, mBatteryProps.batteryVoltage);intent.putExtra(BatteryManager.EXTRA_TEMPERATURE, mBatteryProps.batteryTemperature);intent.putExtra(BatteryManager.EXTRA_TECHNOLOGY, mBatteryProps.batteryTechnology);intent.putExtra(BatteryManager.EXTRA_INVALID_CHARGER, mInvalidCharger);if (DEBUG) {Slog.d(TAG, "Sending ACTION_BATTERY_CHANGED.  level:" + mBatteryProps.batteryLevel +", scale:" + BATTERY_SCALE + ", status:" + mBatteryProps.batteryStatus +", health:" + mBatteryProps.batteryHealth +  ", present:" + mBatteryProps.batteryPresent +", voltage: " + mBatteryProps.batteryVoltage +", temperature: " + mBatteryProps.batteryTemperature +", technology: " + mBatteryProps.batteryTechnology +", AC powered:" + mBatteryProps.chargerAcOnline + ", USB powered:" + mBatteryProps.chargerUsbOnline +", Wireless powered:" + mBatteryProps.chargerWirelessOnline +", icon:" + icon  + ", invalid charger:" + mInvalidCharger);}mHandler.post(new Runnable() {@Overridepublic void run() {ActivityManagerNative.broadcastStickyIntent(intent, null, UserHandle.USER_ALL);}});
}private void logBatteryStatsLocked() {IBinder batteryInfoService = ServiceManager.getService(BatteryStats.SERVICE_NAME);if (batteryInfoService == null) return;DropBoxManager db = (DropBoxManager) mContext.getSystemService(Context.DROPBOX_SERVICE);if (db == null || !db.isTagEnabled("BATTERY_DISCHARGE_INFO")) return;File dumpFile = null;FileOutputStream dumpStream = null;try {// dump the service to a filedumpFile = new File(DUMPSYS_DATA_PATH + BatteryStats.SERVICE_NAME + ".dump");dumpStream = new FileOutputStream(dumpFile);batteryInfoService.dump(dumpStream.getFD(), DUMPSYS_ARGS);FileUtils.sync(dumpStream);// add dump file to drop boxdb.addFile("BATTERY_DISCHARGE_INFO", dumpFile, DropBoxManager.IS_TEXT);} catch (RemoteException e) {Slog.e(TAG, "failed to dump battery service", e);} catch (IOException e) {Slog.e(TAG, "failed to write dumpsys file", e);} finally {// make sure we clean upif (dumpStream != null) {try {dumpStream.close();} catch (IOException e) {Slog.e(TAG, "failed to close dumpsys output stream");}}if (dumpFile != null && !dumpFile.delete()) {Slog.e(TAG, "failed to delete temporary dumpsys file: "+ dumpFile.getAbsolutePath());}}
}private void logOutlierLocked(long duration) {ContentResolver cr = mContext.getContentResolver();String dischargeThresholdString = Settings.Global.getString(cr,Settings.Global.BATTERY_DISCHARGE_THRESHOLD);String durationThresholdString = Settings.Global.getString(cr,Settings.Global.BATTERY_DISCHARGE_DURATION_THRESHOLD);if (dischargeThresholdString != null && durationThresholdString != null) {try {long durationThreshold = Long.parseLong(durationThresholdString);int dischargeThreshold = Integer.parseInt(dischargeThresholdString);if (duration <= durationThreshold &&mDischargeStartLevel - mBatteryProps.batteryLevel >= dischargeThreshold) {// If the discharge cycle is bad enough we want to know about it.logBatteryStatsLocked();}if (DEBUG) Slog.v(TAG, "duration threshold: " + durationThreshold +" discharge threshold: " + dischargeThreshold);if (DEBUG) Slog.v(TAG, "duration: " + duration + " discharge: " +(mDischargeStartLevel - mBatteryProps.batteryLevel));} catch (NumberFormatException e) {Slog.e(TAG, "Invalid DischargeThresholds GService string: " +durationThresholdString + " or " + dischargeThresholdString);return;}}
}private int getIconLocked(int level) {if (mBatteryProps.batteryStatus == BatteryManager.BATTERY_STATUS_CHARGING) {return com.android.internal.R.drawable.stat_sys_battery_charge;} else if (mBatteryProps.batteryStatus == BatteryManager.BATTERY_STATUS_DISCHARGING) {return com.android.internal.R.drawable.stat_sys_battery;} else if (mBatteryProps.batteryStatus == BatteryManager.BATTERY_STATUS_NOT_CHARGING|| mBatteryProps.batteryStatus == BatteryManager.BATTERY_STATUS_FULL) {if (isPoweredLocked(BatteryManager.BATTERY_PLUGGED_ANY)&& mBatteryProps.batteryLevel >= 100) {return com.android.internal.R.drawable.stat_sys_battery_charge;} else {return com.android.internal.R.drawable.stat_sys_battery;}} else {return com.android.internal.R.drawable.stat_sys_battery_unknown;}
}@Override
protected void dump(FileDescriptor fd, PrintWriter pw, String[] args) {if (mContext.checkCallingOrSelfPermission(android.Manifest.permission.DUMP)!= PackageManager.PERMISSION_GRANTED) {pw.println("Permission Denial: can't dump Battery service from from pid="+ Binder.getCallingPid()+ ", uid=" + Binder.getCallingUid());return;}synchronized (mLock) {if (args == null || args.length == 0 || "-a".equals(args[0])) {pw.println("Current Battery Service state:");if (mUpdatesStopped) {pw.println("  (UPDATES STOPPED -- use 'reset' to restart)");}pw.println("  AC powered: " + mBatteryProps.chargerAcOnline);pw.println("  USB powered: " + mBatteryProps.chargerUsbOnline);pw.println("  Wireless powered: " + mBatteryProps.chargerWirelessOnline);pw.println("  status: " + mBatteryProps.batteryStatus);pw.println("  health: " + mBatteryProps.batteryHealth);pw.println("  present: " + mBatteryProps.batteryPresent);pw.println("  level: " + mBatteryProps.batteryLevel);pw.println("  scale: " + BATTERY_SCALE);pw.println("  voltage: " + mBatteryProps.batteryVoltage);if (mBatteryProps.batteryCurrentNow != Integer.MIN_VALUE) {pw.println("  current now: " + mBatteryProps.batteryCurrentNow);}if (mBatteryProps.batteryChargeCounter != Integer.MIN_VALUE) {pw.println("  charge counter: " + mBatteryProps.batteryChargeCounter);}pw.println("  temperature: " + mBatteryProps.batteryTemperature);pw.println("  technology: " + mBatteryProps.batteryTechnology);} else if (args.length == 3 && "set".equals(args[0])) {String key = args[1];String value = args[2];try {boolean update = true;if ("ac".equals(key)) {mBatteryProps.chargerAcOnline = Integer.parseInt(value) != 0;} else if ("usb".equals(key)) {mBatteryProps.chargerUsbOnline = Integer.parseInt(value) != 0;} else if ("wireless".equals(key)) {mBatteryProps.chargerWirelessOnline = Integer.parseInt(value) != 0;} else if ("status".equals(key)) {mBatteryProps.batteryStatus = Integer.parseInt(value);} else if ("level".equals(key)) {mBatteryProps.batteryLevel = Integer.parseInt(value);} else if ("invalid".equals(key)) {mInvalidCharger = Integer.parseInt(value);} else {pw.println("Unknown set option: " + key);update = false;}if (update) {long ident = Binder.clearCallingIdentity();try {mUpdatesStopped = true;processValuesLocked();} finally {Binder.restoreCallingIdentity(ident);}}} catch (NumberFormatException ex) {pw.println("Bad value: " + value);}} else if (args.length == 1 && "reset".equals(args[0])) {long ident = Binder.clearCallingIdentity();try {mUpdatesStopped = false;} finally {Binder.restoreCallingIdentity(ident);}} else {pw.println("Dump current battery state, or:");pw.println("  set ac|usb|wireless|status|level|invalid <value>");pw.println("  reset");}}
}private final UEventObserver mInvalidChargerObserver = new UEventObserver() {@Overridepublic void onUEvent(UEventObserver.UEvent event) {final int invalidCharger = "1".equals(event.get("SWITCH_STATE")) ? 1 : 0;synchronized (mLock) {if (mInvalidCharger != invalidCharger) {mInvalidCharger = invalidCharger;}}}
};private final class Led {private final LightsService.Light mBatteryLight;private final int mBatteryLowARGB;private final int mBatteryMediumARGB;private final int mBatteryFullARGB;private final int mBatteryLedOn;private final int mBatteryLedOff;public Led(Context context, LightsService lights) {mBatteryLight = lights.getLight(LightsService.LIGHT_ID_BATTERY);mBatteryLowARGB = context.getResources().getInteger(com.android.internal.R.integer.config_notificationsBatteryLowARGB);mBatteryMediumARGB = context.getResources().getInteger(com.android.internal.R.integer.config_notificationsBatteryMediumARGB);mBatteryFullARGB = context.getResources().getInteger(com.android.internal.R.integer.config_notificationsBatteryFullARGB);mBatteryLedOn = context.getResources().getInteger(com.android.internal.R.integer.config_notificationsBatteryLedOn);mBatteryLedOff = context.getResources().getInteger(com.android.internal.R.integer.config_notificationsBatteryLedOff);}/*** Synchronize on BatteryService.*/public void updateLightsLocked() {final int level = mBatteryProps.batteryLevel;final int status = mBatteryProps.batteryStatus;if (level < mLowBatteryWarningLevel) {if (status == BatteryManager.BATTERY_STATUS_CHARGING) {// Solid red when battery is chargingmBatteryLight.setColor(mBatteryLowARGB);} else {// Flash red when battery is low and not chargingmBatteryLight.setFlashing(mBatteryLowARGB, LightsService.LIGHT_FLASH_TIMED,mBatteryLedOn, mBatteryLedOff);}} else if (status == BatteryManager.BATTERY_STATUS_CHARGING|| status == BatteryManager.BATTERY_STATUS_FULL) {if (status == BatteryManager.BATTERY_STATUS_FULL || level >= 90) {// Solid green when full or charging and nearly fullmBatteryLight.setColor(mBatteryFullARGB);} else {// Solid orange when charging and halfway fullmBatteryLight.setColor(mBatteryMediumARGB);}} else {// No lights if not charging and not lowmBatteryLight.turnOff();}}
}private final class BatteryListener extends IBatteryPropertiesListener.Stub {public void batteryPropertiesChanged(BatteryProperties props) {BatteryService.this.update(props);}
}

}

总结如下：此服务构造时会注册监听到系统JNI层。当电池电量改变的时候会调用update(BatteryProperties props) -----》processValuesLocked() 。而processValuesLocked() 函数会把电池状态把广播发送出去。其他类再接收广播进行处理

下一个类就是低电量提醒了，文件目录：\frameworks\base\packages\SystemUI\src\com\android\systemui\power\PowerUI.java

[java] view plain copy
/*

Copyright © 2008 The Android Open Source Project
Licensed under the Apache License, Version 2.0 (the “License”);
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an “AS IS” BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package com.android.systemui.power;

import android.app.AlertDialog;
import android.content.BroadcastReceiver;
import android.content.ContentResolver;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.IntentFilter;
import android.media.AudioManager;
import android.media.Ringtone;
import android.media.RingtoneManager;
import android.net.Uri;
import android.os.BatteryManager;
import android.os.Handler;
import android.os.PowerManager;
import android.os.SystemClock;
import android.os.UserHandle;
import android.provider.Settings;
import android.util.Slog;
import android.view.View;
import android.view.WindowManager;
import android.widget.TextView;

import com.android.systemui.R;
import com.android.systemui.SystemUI;

import java.io.FileDescriptor;
import java.io.PrintWriter;
import java.util.Arrays;

public class PowerUI extends SystemUI { //总体说一下，这里才是处理低电量提醒的地方，他接收的广播是Intent.ACTION_BATTERY_CHANGED
static final String TAG = “PowerUI”;

static final boolean DEBUG = false;  Handler mHandler = new Handler();  int mBatteryLevel = 100;
int mBatteryStatus = BatteryManager.BATTERY_STATUS_UNKNOWN;
int mPlugType = 0;
int mInvalidCharger = 0;  int mLowBatteryAlertCloseLevel;
int[] mLowBatteryReminderLevels = new int[2];  AlertDialog mInvalidChargerDialog;
AlertDialog mLowBatteryDialog;
TextView mBatteryLevelTextView;  private long mScreenOffTime = -1;  public void start() {  //这个类会在手机启动后，在SystemUI 里启动(就是系统界面)。  mLowBatteryAlertCloseLevel = mContext.getResources().getInteger( //电量告警取消值，值20   com.android.internal.R.integer.config_lowBatteryCloseWarningLevel);  mLowBatteryReminderLevels[0] = mContext.getResources().getInteger( //低电量提醒 15  com.android.internal.R.integer.config_lowBatteryWarningLevel);  mLowBatteryReminderLevels[1] = mContext.getResources().getInteger( //低电量临界值 4  com.android.internal.R.integer.config_criticalBatteryWarningLevel);  final PowerManager pm = (PowerManager) mContext.getSystemService(Context.POWER_SERVICE);  mScreenOffTime = pm.isScreenOn() ? -1 : SystemClock.elapsedRealtime();  // Register for Intent broadcasts for...  IntentFilter filter = new IntentFilter();  filter.addAction(Intent.ACTION_BATTERY_CHANGED);  filter.addAction(Intent.ACTION_SCREEN_OFF);  filter.addAction(Intent.ACTION_SCREEN_ON);  mContext.registerReceiver(mIntentReceiver, filter, null, mHandler);
}  /** * Buckets the battery level. * * The code in this function is a little weird because I couldn't comprehend * the bucket going up when the battery level was going down. --joeo * * 1 means that the battery is "ok" * 0 means that the battery is between "ok" and what we should warn about. * less than 0 means that the battery is low */
private int findBatteryLevelBucket(int level) {   //这个方法是用来警告判断用的。  if (level >= mLowBatteryAlertCloseLevel) {  return 1;  }  if (level >= mLowBatteryReminderLevels[0]) {  return 0;  }  final int N = mLowBatteryReminderLevels.length;  for (int i=N-1; i>=0; i--) {  if (level <= mLowBatteryReminderLevels[i]) {  return -1-i;  }  }  throw new RuntimeException("not possible!");
}  private BroadcastReceiver mIntentReceiver = new BroadcastReceiver() { //重点，广播接收处理  @Override  public void onReceive(Context context, Intent intent) {  String action = intent.getAction();  if (action.equals(Intent.ACTION_BATTERY_CHANGED)) {  //电池电量改变  final int oldBatteryLevel = mBatteryLevel; //下边就是根据Intent获取BatteryService传过来的电池属性  mBatteryLevel = intent.getIntExtra(BatteryManager.EXTRA_LEVEL, 100); /  final int oldBatteryStatus = mBatteryStatus;  mBatteryStatus = intent.getIntExtra(BatteryManager.EXTRA_STATUS,  BatteryManager.BATTERY_STATUS_UNKNOWN);  final int oldPlugType = mPlugType;  mPlugType = intent.getIntExtra(BatteryManager.EXTRA_PLUGGED, 1);  final int oldInvalidCharger = mInvalidCharger;  mInvalidCharger = intent.getIntExtra(BatteryManager.EXTRA_INVALID_CHARGER, 0);  final boolean plugged = mPlugType != 0;  final boolean oldPlugged = oldPlugType != 0;  int oldBucket = findBatteryLevelBucket(oldBatteryLevel); //这两个值特别有意思，就是说记录下老的电量，记录一下新的电量，比较电量是增加了，还是减小了  int bucket = findBatteryLevelBucket(mBatteryLevel);  if (DEBUG) {  Slog.d(TAG, "buckets   ....." + mLowBatteryAlertCloseLevel  + " .. " + mLowBatteryReminderLevels[0]  + " .. " + mLowBatteryReminderLevels[1]);  Slog.d(TAG, "level          " + oldBatteryLevel + " --> " + mBatteryLevel);  Slog.d(TAG, "status         " + oldBatteryStatus + " --> " + mBatteryStatus);  Slog.d(TAG, "plugType       " + oldPlugType + " --> " + mPlugType);  Slog.d(TAG, "invalidCharger " + oldInvalidCharger + " --> " + mInvalidCharger);  Slog.d(TAG, "bucket         " + oldBucket + " --> " + bucket);  Slog.d(TAG, "plugged        " + oldPlugged + " --> " + plugged);  }  if (oldInvalidCharger == 0 && mInvalidCharger != 0) {  Slog.d(TAG, "showing invalid charger warning");  showInvalidChargerDialog(); //就是充电器不识别的弹窗  return;  } else if (oldInvalidCharger != 0 && mInvalidCharger == 0) {  dismissInvalidChargerDialog();  } else if (mInvalidChargerDialog != null) {  // if invalid charger is showing, don't show low battery  return;  }  if (!plugged  && (bucket < oldBucket || oldPlugged)  && mBatteryStatus != BatteryManager.BATTERY_STATUS_UNKNOWN  && bucket < 0) {  showLowBatteryWarning(); <span style="color:#FF0000;">//这里哈，低电量提醒的弹窗</span>  // only play SFX when the dialog comes up or the bucket changes  if (bucket != oldBucket || oldPlugged) {  playLowBatterySound();  }  } else if (plugged || (bucket > oldBucket && bucket > 0)) { //插上充电器或者充电电池电量超过20取消弹窗  dismissLowBatteryWarning();  } else if (mBatteryLevelTextView != null) {  showLowBatteryWarning();  }  } else if (Intent.ACTION_SCREEN_OFF.equals(action)) {  mScreenOffTime = SystemClock.elapsedRealtime();  } else if (Intent.ACTION_SCREEN_ON.equals(action)) {  mScreenOffTime = -1;  } else {  Slog.w(TAG, "unknown intent: " + intent);  }  }
};  void dismissLowBatteryWarning() {  if (mLowBatteryDialog != null) {  Slog.i(TAG, "closing low battery warning: level=" + mBatteryLevel);  mLowBatteryDialog.dismiss();  }
}  void showLowBatteryWarning() {  Slog.i(TAG,  ((mBatteryLevelTextView == null) ? "showing" : "updating")  + " low battery warning: level=" + mBatteryLevel  + " [" + findBatteryLevelBucket(mBatteryLevel) + "]");  CharSequence levelText = mContext.getString(  R.string.battery_low_percent_format, mBatteryLevel);  if (mBatteryLevelTextView != null) {  mBatteryLevelTextView.setText(levelText);  } else {  View v = View.inflate(mContext, R.layout.battery_low, null);  mBatteryLevelTextView = (TextView)v.findViewById(R.id.level_percent);  mBatteryLevelTextView.setText(levelText);  AlertDialog.Builder b = new AlertDialog.Builder(mContext);  b.setCancelable(true);  b.setTitle(R.string.battery_low_title);  b.setView(v);  b.setIconAttribute(android.R.attr.alertDialogIcon);  b.setPositiveButton(android.R.string.ok, null);  final Intent intent = new Intent(Intent.ACTION_POWER_USAGE_SUMMARY);  intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK  | Intent.FLAG_ACTIVITY_MULTIPLE_TASK  | Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS  | Intent.FLAG_ACTIVITY_NO_HISTORY);  if (intent.resolveActivity(mContext.getPackageManager()) != null) {  b.setNegativeButton(R.string.battery_low_why,  new DialogInterface.OnClickListener() {  @Override  public void onClick(DialogInterface dialog, int which) {  mContext.startActivityAsUser(intent, UserHandle.CURRENT);  dismissLowBatteryWarning();  }  });  }  AlertDialog d = b.create();  d.setOnDismissListener(new DialogInterface.OnDismissListener() {  @Override  public void onDismiss(DialogInterface dialog) {  mLowBatteryDialog = null;  mBatteryLevelTextView = null;  }  });  d.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);  d.getWindow().getAttributes().privateFlags |=  WindowManager.LayoutParams.PRIVATE_FLAG_SHOW_FOR_ALL_USERS;  d.show();  mLowBatteryDialog = d;  }
}  void playLowBatterySound() {  final ContentResolver cr = mContext.getContentResolver();  final int silenceAfter = Settings.Global.getInt(cr,  Settings.Global.LOW_BATTERY_SOUND_TIMEOUT, 0);  final long offTime = SystemClock.elapsedRealtime() - mScreenOffTime;  if (silenceAfter > 0  && mScreenOffTime > 0  && offTime > silenceAfter) {  Slog.i(TAG, "screen off too long (" + offTime + "ms, limit " + silenceAfter  + "ms): not waking up the user with low battery sound");  return;  }  if (DEBUG) {  Slog.d(TAG, "playing low battery sound. pick-a-doop!"); // WOMP-WOMP is deprecated  }  if (Settings.Global.getInt(cr, Settings.Global.POWER_SOUNDS_ENABLED, 1) == 1) {  final String soundPath = Settings.Global.getString(cr,  Settings.Global.LOW_BATTERY_SOUND);  if (soundPath != null) {  final Uri soundUri = Uri.parse("file://" + soundPath);  if (soundUri != null) {  final Ringtone sfx = RingtoneManager.getRingtone(mContext, soundUri);  if (sfx != null) {  sfx.setStreamType(AudioManager.STREAM_SYSTEM);  sfx.play();  }  }  }  }
}  void dismissInvalidChargerDialog() {  if (mInvalidChargerDialog != null) {  mInvalidChargerDialog.dismiss();  }
}  void showInvalidChargerDialog() {  Slog.d(TAG, "showing invalid charger dialog");  dismissLowBatteryWarning();  AlertDialog.Builder b = new AlertDialog.Builder(mContext);  b.setCancelable(true);  b.setMessage(R.string.invalid_charger);  b.setIconAttribute(android.R.attr.alertDialogIcon);  b.setPositiveButton(android.R.string.ok, null);  AlertDialog d = b.create();  d.setOnDismissListener(new DialogInterface.OnDismissListener() {  public void onDismiss(DialogInterface dialog) {  mInvalidChargerDialog = null;  mBatteryLevelTextView = null;  }  });  d.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);  d.show();  mInvalidChargerDialog = d;
}  public void dump(FileDescriptor fd, PrintWriter pw, String[] args) {  pw.print("mLowBatteryAlertCloseLevel=");  pw.println(mLowBatteryAlertCloseLevel);  pw.print("mLowBatteryReminderLevels=");  pw.println(Arrays.toString(mLowBatteryReminderLevels));  pw.print("mInvalidChargerDialog=");  pw.println(mInvalidChargerDialog == null ? "null" : mInvalidChargerDialog.toString());  pw.print("mLowBatteryDialog=");  pw.println(mLowBatteryDialog == null ? "null" : mLowBatteryDialog.toString());  pw.print("mBatteryLevel=");  pw.println(Integer.toString(mBatteryLevel));  pw.print("mBatteryStatus=");  pw.println(Integer.toString(mBatteryStatus));  pw.print("mPlugType=");  pw.println(Integer.toString(mPlugType));  pw.print("mInvalidCharger=");  pw.println(Integer.toString(mInvalidCharger));  pw.print("mScreenOffTime=");  pw.print(mScreenOffTime);  if (mScreenOffTime >= 0) {  pw.print(" (");  pw.print(SystemClock.elapsedRealtime() - mScreenOffTime);  pw.print(" ago)");  }  pw.println();  pw.print("soundTimeout=");  pw.println(Settings.Global.getInt(mContext.getContentResolver(),  Settings.Global.LOW_BATTERY_SOUND_TIMEOUT, 0));  pw.print("bucket: ");  pw.println(Integer.toString(findBatteryLevelBucket(mBatteryLevel)));
}

}
/*

Copyright © 2008 The Android Open Source Project
Licensed under the Apache License, Version 2.0 (the “License”);
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an “AS IS” BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package com.android.systemui.power;

import com.android.systemui.R;
import com.android.systemui.SystemUI;

import java.io.FileDescriptor;
import java.io.PrintWriter;
import java.util.Arrays;

public class PowerUI extends SystemUI { //总体说一下，这里才是处理低电量提醒的地方，他接收的广播是Intent.ACTION_BATTERY_CHANGED
static final String TAG = “PowerUI”;

static final boolean DEBUG = false;Handler mHandler = new Handler();int mBatteryLevel = 100;
int mBatteryStatus = BatteryManager.BATTERY_STATUS_UNKNOWN;
int mPlugType = 0;
int mInvalidCharger = 0;int mLowBatteryAlertCloseLevel;
int[] mLowBatteryReminderLevels = new int[2];AlertDialog mInvalidChargerDialog;
AlertDialog mLowBatteryDialog;
TextView mBatteryLevelTextView;private long mScreenOffTime = -1;public void start() {  //这个类会在手机启动后，在SystemUI 里启动(就是系统界面)。mLowBatteryAlertCloseLevel = mContext.getResources().getInteger( //电量告警取消值，值20 com.android.internal.R.integer.config_lowBatteryCloseWarningLevel);mLowBatteryReminderLevels[0] = mContext.getResources().getInteger( //低电量提醒 15com.android.internal.R.integer.config_lowBatteryWarningLevel);mLowBatteryReminderLevels[1] = mContext.getResources().getInteger( //低电量临界值 4com.android.internal.R.integer.config_criticalBatteryWarningLevel);final PowerManager pm = (PowerManager) mContext.getSystemService(Context.POWER_SERVICE);mScreenOffTime = pm.isScreenOn() ? -1 : SystemClock.elapsedRealtime();// Register for Intent broadcasts for...IntentFilter filter = new IntentFilter();filter.addAction(Intent.ACTION_BATTERY_CHANGED);filter.addAction(Intent.ACTION_SCREEN_OFF);filter.addAction(Intent.ACTION_SCREEN_ON);mContext.registerReceiver(mIntentReceiver, filter, null, mHandler);
}/*** Buckets the battery level.** The code in this function is a little weird because I couldn't comprehend* the bucket going up when the battery level was going down. --joeo** 1 means that the battery is "ok"* 0 means that the battery is between "ok" and what we should warn about.* less than 0 means that the battery is low*/
private int findBatteryLevelBucket(int level) {   //这个方法是用来警告判断用的。if (level >= mLowBatteryAlertCloseLevel) {return 1;}if (level >= mLowBatteryReminderLevels[0]) {return 0;}final int N = mLowBatteryReminderLevels.length;for (int i=N-1; i>=0; i--) {if (level <= mLowBatteryReminderLevels[i]) {return -1-i;}}throw new RuntimeException("not possible!");
}private BroadcastReceiver mIntentReceiver = new BroadcastReceiver() { //重点，广播接收处理@Overridepublic void onReceive(Context context, Intent intent) {String action = intent.getAction();if (action.equals(Intent.ACTION_BATTERY_CHANGED)) {  //电池电量改变final int oldBatteryLevel = mBatteryLevel; //下边就是根据Intent获取BatteryService传过来的电池属性mBatteryLevel = intent.getIntExtra(BatteryManager.EXTRA_LEVEL, 100); /final int oldBatteryStatus = mBatteryStatus;mBatteryStatus = intent.getIntExtra(BatteryManager.EXTRA_STATUS,BatteryManager.BATTERY_STATUS_UNKNOWN);final int oldPlugType = mPlugType;mPlugType = intent.getIntExtra(BatteryManager.EXTRA_PLUGGED, 1);final int oldInvalidCharger = mInvalidCharger;mInvalidCharger = intent.getIntExtra(BatteryManager.EXTRA_INVALID_CHARGER, 0);final boolean plugged = mPlugType != 0;final boolean oldPlugged = oldPlugType != 0;int oldBucket = findBatteryLevelBucket(oldBatteryLevel); //这两个值特别有意思，就是说记录下老的电量，记录一下新的电量，比较电量是增加了，还是减小了int bucket = findBatteryLevelBucket(mBatteryLevel);if (DEBUG) {Slog.d(TAG, "buckets   ....." + mLowBatteryAlertCloseLevel+ " .. " + mLowBatteryReminderLevels[0]+ " .. " + mLowBatteryReminderLevels[1]);Slog.d(TAG, "level          " + oldBatteryLevel + " --> " + mBatteryLevel);Slog.d(TAG, "status         " + oldBatteryStatus + " --> " + mBatteryStatus);Slog.d(TAG, "plugType       " + oldPlugType + " --> " + mPlugType);Slog.d(TAG, "invalidCharger " + oldInvalidCharger + " --> " + mInvalidCharger);Slog.d(TAG, "bucket         " + oldBucket + " --> " + bucket);Slog.d(TAG, "plugged        " + oldPlugged + " --> " + plugged);}if (oldInvalidCharger == 0 && mInvalidCharger != 0) {Slog.d(TAG, "showing invalid charger warning");showInvalidChargerDialog(); //就是充电器不识别的弹窗return;} else if (oldInvalidCharger != 0 && mInvalidCharger == 0) {dismissInvalidChargerDialog();} else if (mInvalidChargerDialog != null) {// if invalid charger is showing, don't show low batteryreturn;}if (!plugged&& (bucket < oldBucket || oldPlugged)&& mBatteryStatus != BatteryManager.BATTERY_STATUS_UNKNOWN&& bucket < 0) {showLowBatteryWarning(); <span style="color:#FF0000;">//这里哈，低电量提醒的弹窗</span>// only play SFX when the dialog comes up or the bucket changesif (bucket != oldBucket || oldPlugged) {playLowBatterySound();}} else if (plugged || (bucket > oldBucket && bucket > 0)) { //插上充电器或者充电电池电量超过20取消弹窗dismissLowBatteryWarning();} else if (mBatteryLevelTextView != null) {showLowBatteryWarning();}} else if (Intent.ACTION_SCREEN_OFF.equals(action)) {mScreenOffTime = SystemClock.elapsedRealtime();} else if (Intent.ACTION_SCREEN_ON.equals(action)) {mScreenOffTime = -1;} else {Slog.w(TAG, "unknown intent: " + intent);}}
};void dismissLowBatteryWarning() {if (mLowBatteryDialog != null) {Slog.i(TAG, "closing low battery warning: level=" + mBatteryLevel);mLowBatteryDialog.dismiss();}
}void showLowBatteryWarning() {Slog.i(TAG,((mBatteryLevelTextView == null) ? "showing" : "updating")+ " low battery warning: level=" + mBatteryLevel+ " [" + findBatteryLevelBucket(mBatteryLevel) + "]");CharSequence levelText = mContext.getString(R.string.battery_low_percent_format, mBatteryLevel);if (mBatteryLevelTextView != null) {mBatteryLevelTextView.setText(levelText);} else {View v = View.inflate(mContext, R.layout.battery_low, null);mBatteryLevelTextView = (TextView)v.findViewById(R.id.level_percent);mBatteryLevelTextView.setText(levelText);AlertDialog.Builder b = new AlertDialog.Builder(mContext);b.setCancelable(true);b.setTitle(R.string.battery_low_title);b.setView(v);b.setIconAttribute(android.R.attr.alertDialogIcon);b.setPositiveButton(android.R.string.ok, null);final Intent intent = new Intent(Intent.ACTION_POWER_USAGE_SUMMARY);intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK| Intent.FLAG_ACTIVITY_MULTIPLE_TASK| Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS| Intent.FLAG_ACTIVITY_NO_HISTORY);if (intent.resolveActivity(mContext.getPackageManager()) != null) {b.setNegativeButton(R.string.battery_low_why,new DialogInterface.OnClickListener() {@Overridepublic void onClick(DialogInterface dialog, int which) {mContext.startActivityAsUser(intent, UserHandle.CURRENT);dismissLowBatteryWarning();}});}AlertDialog d = b.create();d.setOnDismissListener(new DialogInterface.OnDismissListener() {@Overridepublic void onDismiss(DialogInterface dialog) {mLowBatteryDialog = null;mBatteryLevelTextView = null;}});d.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);d.getWindow().getAttributes().privateFlags |=WindowManager.LayoutParams.PRIVATE_FLAG_SHOW_FOR_ALL_USERS;d.show();mLowBatteryDialog = d;}
}void playLowBatterySound() {final ContentResolver cr = mContext.getContentResolver();final int silenceAfter = Settings.Global.getInt(cr,Settings.Global.LOW_BATTERY_SOUND_TIMEOUT, 0);final long offTime = SystemClock.elapsedRealtime() - mScreenOffTime;if (silenceAfter > 0&& mScreenOffTime > 0&& offTime > silenceAfter) {Slog.i(TAG, "screen off too long (" + offTime + "ms, limit " + silenceAfter+ "ms): not waking up the user with low battery sound");return;}if (DEBUG) {Slog.d(TAG, "playing low battery sound. pick-a-doop!"); // WOMP-WOMP is deprecated}if (Settings.Global.getInt(cr, Settings.Global.POWER_SOUNDS_ENABLED, 1) == 1) {final String soundPath = Settings.Global.getString(cr,Settings.Global.LOW_BATTERY_SOUND);if (soundPath != null) {final Uri soundUri = Uri.parse("file://" + soundPath);if (soundUri != null) {final Ringtone sfx = RingtoneManager.getRingtone(mContext, soundUri);if (sfx != null) {sfx.setStreamType(AudioManager.STREAM_SYSTEM);sfx.play();}}}}
}void dismissInvalidChargerDialog() {if (mInvalidChargerDialog != null) {mInvalidChargerDialog.dismiss();}
}void showInvalidChargerDialog() {Slog.d(TAG, "showing invalid charger dialog");dismissLowBatteryWarning();AlertDialog.Builder b = new AlertDialog.Builder(mContext);b.setCancelable(true);b.setMessage(R.string.invalid_charger);b.setIconAttribute(android.R.attr.alertDialogIcon);b.setPositiveButton(android.R.string.ok, null);AlertDialog d = b.create();d.setOnDismissListener(new DialogInterface.OnDismissListener() {public void onDismiss(DialogInterface dialog) {mInvalidChargerDialog = null;mBatteryLevelTextView = null;}});d.getWindow().setType(WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);d.show();mInvalidChargerDialog = d;
}public void dump(FileDescriptor fd, PrintWriter pw, String[] args) {pw.print("mLowBatteryAlertCloseLevel=");pw.println(mLowBatteryAlertCloseLevel);pw.print("mLowBatteryReminderLevels=");pw.println(Arrays.toString(mLowBatteryReminderLevels));pw.print("mInvalidChargerDialog=");pw.println(mInvalidChargerDialog == null ? "null" : mInvalidChargerDialog.toString());pw.print("mLowBatteryDialog=");pw.println(mLowBatteryDialog == null ? "null" : mLowBatteryDialog.toString());pw.print("mBatteryLevel=");pw.println(Integer.toString(mBatteryLevel));pw.print("mBatteryStatus=");pw.println(Integer.toString(mBatteryStatus));pw.print("mPlugType=");pw.println(Integer.toString(mPlugType));pw.print("mInvalidCharger=");pw.println(Integer.toString(mInvalidCharger));pw.print("mScreenOffTime=");pw.print(mScreenOffTime);if (mScreenOffTime >= 0) {pw.print(" (");pw.print(SystemClock.elapsedRealtime() - mScreenOffTime);pw.print(" ago)");}pw.println();pw.print("soundTimeout=");pw.println(Settings.Global.getInt(mContext.getContentResolver(),Settings.Global.LOW_BATTERY_SOUND_TIMEOUT, 0));pw.print("bucket: ");pw.println(Integer.toString(findBatteryLevelBucket(mBatteryLevel)));
}

}

总结一下：这个类就是接收电池电量改变的广播，然后弹窗提醒。

下一个类就是没电关机界面了，文件目录：\frameworks\base\services\java\com\android\server\ShutdownLowBatteryActivity.java

这个Activity的配置文件是这样的（\frameworks\base\core\res\AndroidManifest.xml）：

[html] view plain copy

android:theme="@android:style/Theme.Translucent.NoTitleBar"是API小于11的透明主题。这样弹出的dialog会是老版本的主题。（这个Activity是透明的）

对于Theme，因为是4.4，我更倾向于：android:theme=“@android:style/Theme.Holo.Panel”

ShutdownLowBatteryActivity.java：

[java] view plain copy
/*

Licensed under the Apache License, Version 2.0 (the “License”);
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an “AS IS” BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package com.android.server;

import android.app.Activity;
import android.app.AlertDialog;
import android.app.KeyguardManager;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.os.Handler;
import android.util.Slog;
import android.view.Window;
import android.view.WindowManager;
import android.view.View;

//import com.android.internal.app.ShutdownThread;
import com.android.server.power.ShutdownThread;

import android.telephony.TelephonyManager;
import android.telephony.PhoneStateListener;
import android.media.MediaPlayer;
import android.media.MediaPlayer.OnCompletionListener;
import android.content.ContentResolver;
import android.provider.Settings;

import java.io.IOException;

public class ShutdownLowBatteryActivity extends Activity {

private static final String TAG = "ShutdownLowBatteryActivity";
private boolean mConfirm;
private int mSeconds = 15;//电池电量等于0 15秒内不插充电器就自动关机
private AlertDialog mDialog;
private Handler myHandler = new Handler();
private Runnable myRunnable = new Runnable() { //这里数秒关机  @Override  public void run() {  mSeconds --;  if(mSeconds <1)  mSeconds=0;  mDialog.setMessage(getString(com.android.internal.R.string.low_battery_shutdown_after_seconds,mSeconds));  if(mSeconds <= 1){  myHandler.removeCallbacks(myRunnable);  Handler h = new Handler();  h.post(new Runnable() {  public void run() {  ShutdownThread.shutdown(ShutdownLowBatteryActivity.this, mConfirm);  }  });  }  myHandler.postDelayed(myRunnable,1000);  }
};  private BroadcastReceiver mReceiver;
private MediaPlayer mplayer;  @Override
protected void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  mConfirm = getIntent().getBooleanExtra(Intent.EXTRA_KEY_CONFIRM, false);  Slog.i(TAG, "onCreate(): confirm=" + mConfirm);  //if(getIntent().getBooleanExtra("can_be_cancel", false)) { //这行注释掉了： 然后当连上充电器后或者电量涨到20的时候，就取消倒计时关机  mReceiver = new BroadcastReceiver() {  @Override  public void onReceive(Context context, Intent intent) {  if(Intent.ACTION_BATTERY_OKAY.equals(intent.getAction())|  Intent.ACTION_POWER_CONNECTED.equals(intent.getAction())){  ShutDownWakeLock.releaseCpuLock();  myHandler.removeCallbacks(myRunnable);  if(mReceiver != null)  unregisterReceiver(mReceiver);  finish();  }  }  };  IntentFilter filter=new IntentFilter(Intent.ACTION_POWER_CONNECTED);  filter.addAction(Intent.ACTION_BATTERY_OKAY);  registerReceiver(mReceiver, filter);  //}  PhoneStateListener mPhoneStateListener = new PhoneStateListener() { //如果正数秒呢，电话呼入了。取消自动关机  @Override  public void onCallStateChanged(int state, String ignored) {  if (state == TelephonyManager.CALL_STATE_RINGING) {  ShutDownWakeLock.releaseCpuLock();  myHandler.removeCallbacks(myRunnable);  finish();  }  }  };  TelephonyManager mTelephonyManager = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE);  mTelephonyManager.listen(mPhoneStateListener,  PhoneStateListener.LISTEN_CALL_STATE);  requestWindowFeature(android.view.Window.FEATURE_NO_TITLE);  Window win = getWindow();  win.addFlags(WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED  | WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD);  win.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON  | WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON);  setContentView(new View(this));  mDialog=new AlertDialog.Builder(this).create();  mDialog.setTitle(com.android.internal.R.string.low_battery_shutdown_title);  mDialog.setMessage(getString(com.android.internal.R.string.low_battery_shutdown_after_seconds,mSeconds));  if(!getIntent().getBooleanExtra("cant_be_cancel_by_button", false)) {//读取配置文件，是否运行取消，然后根据这个显示取消自动关机按钮  mDialog.setButton(DialogInterface.BUTTON_NEUTRAL,getText(com.android.internal.R.string.cancel), new DialogInterface.OnClickListener() {  @Override  public void onClick(DialogInterface dialog, int which) {  myHandler.removeCallbacks(myRunnable);  dialog.cancel();  if(mReceiver != null)  unregisterReceiver(mReceiver);  finish();  }});  }  mDialog.setCancelable(false);  //mDialog.getWindow().setType( WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);  mDialog.show();  if(mConfirm == false){  myHandler.postDelayed(myRunnable, 1000);  }  myHandler.post(new Runnable(){  public void run(){  final ContentResolver cr = getContentResolver();  String path=Settings.System.getString(cr,Settings.System.NOTIFICATION_SOUND);  mplayer=new MediaPlayer();  try{  mplayer.reset();  mplayer.setDataSource("system/media/audio/ui/LowBattery.ogg");                    mplayer.prepare();  mplayer.start();  mplayer.setOnCompletionListener(new OnCompletionListener() {  @Override  public void onCompletion(MediaPlayer mp) {  if(null != mplayer){  mplayer.stop();  mplayer.release();  mplayer = null;  }  }  });  }  catch(IOException e){  }  }  });
}

}
/*

Licensed under the Apache License, Version 2.0 (the “License”);
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an “AS IS” BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package com.android.server;

//import com.android.internal.app.ShutdownThread;
import com.android.server.power.ShutdownThread;

import java.io.IOException;

public class ShutdownLowBatteryActivity extends Activity {

private static final String TAG = "ShutdownLowBatteryActivity";
private boolean mConfirm;
private int mSeconds = 15;//电池电量等于0 15秒内不插充电器就自动关机
private AlertDialog mDialog;
private Handler myHandler = new Handler();
private Runnable myRunnable = new Runnable() { //这里数秒关机@Overridepublic void run() {mSeconds --;if(mSeconds <1)mSeconds=0;mDialog.setMessage(getString(com.android.internal.R.string.low_battery_shutdown_after_seconds,mSeconds));if(mSeconds <= 1){myHandler.removeCallbacks(myRunnable);Handler h = new Handler();h.post(new Runnable() {public void run() {ShutdownThread.shutdown(ShutdownLowBatteryActivity.this, mConfirm);}});}myHandler.postDelayed(myRunnable,1000);}
};private BroadcastReceiver mReceiver;
private MediaPlayer mplayer;@Override
protected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);mConfirm = getIntent().getBooleanExtra(Intent.EXTRA_KEY_CONFIRM, false);Slog.i(TAG, "onCreate(): confirm=" + mConfirm);//if(getIntent().getBooleanExtra("can_be_cancel", false)) { //这行注释掉了： 然后当连上充电器后或者电量涨到20的时候，就取消倒计时关机mReceiver = new BroadcastReceiver() {@Overridepublic void onReceive(Context context, Intent intent) {if(Intent.ACTION_BATTERY_OKAY.equals(intent.getAction())|Intent.ACTION_POWER_CONNECTED.equals(intent.getAction())){ShutDownWakeLock.releaseCpuLock();myHandler.removeCallbacks(myRunnable);if(mReceiver != null)unregisterReceiver(mReceiver);finish();}}};IntentFilter filter=new IntentFilter(Intent.ACTION_POWER_CONNECTED);filter.addAction(Intent.ACTION_BATTERY_OKAY);registerReceiver(mReceiver, filter);//}PhoneStateListener mPhoneStateListener = new PhoneStateListener() { //如果正数秒呢，电话呼入了。取消自动关机@Overridepublic void onCallStateChanged(int state, String ignored) {if (state == TelephonyManager.CALL_STATE_RINGING) {ShutDownWakeLock.releaseCpuLock();myHandler.removeCallbacks(myRunnable);finish();}}};TelephonyManager mTelephonyManager = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE);mTelephonyManager.listen(mPhoneStateListener,PhoneStateListener.LISTEN_CALL_STATE);requestWindowFeature(android.view.Window.FEATURE_NO_TITLE);Window win = getWindow();win.addFlags(WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED| WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD);win.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON| WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON);setContentView(new View(this));mDialog=new AlertDialog.Builder(this).create();mDialog.setTitle(com.android.internal.R.string.low_battery_shutdown_title);mDialog.setMessage(getString(com.android.internal.R.string.low_battery_shutdown_after_seconds,mSeconds));if(!getIntent().getBooleanExtra("cant_be_cancel_by_button", false)) {//读取配置文件，是否运行取消，然后根据这个显示取消自动关机按钮mDialog.setButton(DialogInterface.BUTTON_NEUTRAL,getText(com.android.internal.R.string.cancel), new DialogInterface.OnClickListener() {@Overridepublic void onClick(DialogInterface dialog, int which) {myHandler.removeCallbacks(myRunnable);dialog.cancel();if(mReceiver != null)unregisterReceiver(mReceiver);finish();}});}mDialog.setCancelable(false);//mDialog.getWindow().setType( WindowManager.LayoutParams.TYPE_SYSTEM_ALERT);mDialog.show();if(mConfirm == false){myHandler.postDelayed(myRunnable, 1000);}myHandler.post(new Runnable(){public void run(){final ContentResolver cr = getContentResolver();String path=Settings.System.getString(cr,Settings.System.NOTIFICATION_SOUND);mplayer=new MediaPlayer();try{mplayer.reset();mplayer.setDataSource("system/media/audio/ui/LowBattery.ogg");                  mplayer.prepare();mplayer.start();mplayer.setOnCompletionListener(new OnCompletionListener() {@Overridepublic void onCompletion(MediaPlayer mp) {if(null != mplayer){mplayer.stop();mplayer.release();mplayer = null;}}});}catch(IOException e){}}});
}

}

总结如下：这个类就是弹窗计时，提醒不连充电器就要关机了。

最后一个相关的类，文件路径：\frameworks\base\packages\SystemUI\src\com\android\systemui\BatteryMeterView.java

这个类是自定义控件，定义在手机状态栏里：

[java] view plain copy
/*

Licensed under the Apache License, Version 2.0 (the “License”);
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an “AS IS” BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package com.android.systemui;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.res.Resources;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.RectF;
import android.graphics.Typeface;
import android.os.BatteryManager;
import android.os.Bundle;
import android.provider.Settings;
import android.util.AttributeSet;
import android.view.View;

public class BatteryMeterView extends View implements DemoMode {
public static final String TAG = BatteryMeterView.class.getSimpleName();
public static final String ACTION_LEVEL_TEST = “com.android.systemui.BATTERY_LEVEL_TEST”;

public static final boolean ENABLE_PERCENT = true;
public static final boolean SINGLE_DIGIT_PERCENT = false;
public static final boolean SHOW_100_PERCENT = false;  public static final int FULL = 96;
public static final int EMPTY = 4;  public static final float SUBPIXEL = 0.4f;  // inset rects for softer edges  int[] mColors;  boolean mShowPercent = true;
Paint mFramePaint, mBatteryPaint, mWarningTextPaint, mTextPaint, mBoltPaint;
int mButtonHeight;
private float mTextHeight, mWarningTextHeight;  private int mHeight;
private int mWidth;
private String mWarningString;
private final int mChargeColor;
private final float[] mBoltPoints;
private final Path mBoltPath = new Path();  private final RectF mFrame = new RectF();
private final RectF mButtonFrame = new RectF();
private final RectF mClipFrame = new RectF();
private final RectF mBoltFrame = new RectF();  private class BatteryTracker extends BroadcastReceiver {  public static final int UNKNOWN_LEVEL = -1;  // current battery status  int level = UNKNOWN_LEVEL;  String percentStr;  int plugType;  boolean plugged;  int health;  int status;  String technology;  int voltage;  int temperature;  boolean testmode = false;  @Override  public void onReceive(Context context, Intent intent) {  final String action = intent.getAction();  if (action.equals(Intent.ACTION_BATTERY_CHANGED)) { //接收电量改变的广播，取电池状态的属性  if (testmode && ! intent.getBooleanExtra("testmode", false)) return;  level = (int)(100f  * intent.getIntExtra(BatteryManager.EXTRA_LEVEL, 0)  / intent.getIntExtra(BatteryManager.EXTRA_SCALE, 100));  plugType = intent.getIntExtra(BatteryManager.EXTRA_PLUGGED, 0);  plugged = plugType != 0;  health = intent.getIntExtra(BatteryManager.EXTRA_HEALTH,  BatteryManager.BATTERY_HEALTH_UNKNOWN);  status = intent.getIntExtra(BatteryManager.EXTRA_STATUS,  BatteryManager.BATTERY_STATUS_UNKNOWN);  technology = intent.getStringExtra(BatteryManager.EXTRA_TECHNOLOGY);  voltage = intent.getIntExtra(BatteryManager.EXTRA_VOLTAGE, 0);  temperature = intent.getIntExtra(BatteryManager.EXTRA_TEMPERATURE, 0);  setContentDescription(  context.getString(R.string.accessibility_battery_level, level));  postInvalidate();  } else if (action.equals(ACTION_LEVEL_TEST)) {  testmode = true;  post(new Runnable() {  int curLevel = 0;  int incr = 1;  int saveLevel = level;  int savePlugged = plugType;  Intent dummy = new Intent(Intent.ACTION_BATTERY_CHANGED);  @Override  public void run() {  if (curLevel < 0) {  testmode = false;  dummy.putExtra("level", saveLevel);  dummy.putExtra("plugged", savePlugged);  dummy.putExtra("testmode", false);  } else {  dummy.putExtra("level", curLevel);  dummy.putExtra("plugged", incr > 0 ? BatteryManager.BATTERY_PLUGGED_AC : 0);  dummy.putExtra("testmode", true);  }  getContext().sendBroadcast(dummy);  if (!testmode) return;  curLevel += incr;  if (curLevel == 100) {  incr *= -1;  }  postDelayed(this, 200);  }  });  }  }
}  BatteryTracker mTracker = new BatteryTracker();  @Override
public void onAttachedToWindow() {  super.onAttachedToWindow();  IntentFilter filter = new IntentFilter();  filter.addAction(Intent.ACTION_BATTERY_CHANGED);  filter.addAction(ACTION_LEVEL_TEST);  final Intent sticky = getContext().registerReceiver(mTracker, filter);  if (sticky != null) {  // preload the battery level  mTracker.onReceive(getContext(), sticky);  }
}  @Override
public void onDetachedFromWindow() {  super.onDetachedFromWindow();  getContext().unregisterReceiver(mTracker);
}  public BatteryMeterView(Context context) {  this(context, null, 0);
}  public BatteryMeterView(Context context, AttributeSet attrs) {  this(context, attrs, 0);
}  public BatteryMeterView(Context context, AttributeSet attrs, int defStyle) {  super(context, attrs, defStyle);  final Resources res = context.getResources();  TypedArray levels = res.obtainTypedArray(R.array.batterymeter_color_levels);  TypedArray colors = res.obtainTypedArray(R.array.batterymeter_color_values);  final int N = levels.length();  mColors = new int[2*N];  for (int i=0; i<N; i++) {  mColors[2*i] = levels.getInt(i, 0);  mColors[2*i+1] = colors.getColor(i, 0);  }  levels.recycle();  colors.recycle();  mShowPercent = ENABLE_PERCENT && 0 != Settings.System.getInt(  context.getContentResolver(), "status_bar_show_battery_percent", 0);  mWarningString = context.getString(R.string.battery_meter_very_low_overlay_symbol);  mFramePaint = new Paint(Paint.ANTI_ALIAS_FLAG);  mFramePaint.setColor(res.getColor(R.color.batterymeter_frame_color));  mFramePaint.setDither(true);  mFramePaint.setStrokeWidth(0);  mFramePaint.setStyle(Paint.Style.FILL_AND_STROKE);  mFramePaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_ATOP));  mBatteryPaint = new Paint(Paint.ANTI_ALIAS_FLAG);  mBatteryPaint.setDither(true);  mBatteryPaint.setStrokeWidth(0);  mBatteryPaint.setStyle(Paint.Style.FILL_AND_STROKE);  mTextPaint = new Paint(Paint.ANTI_ALIAS_FLAG);  mTextPaint.setColor(0xFFFFFFFF);  Typeface font = Typeface.create("sans-serif-condensed", Typeface.NORMAL);  mTextPaint.setTypeface(font);  mTextPaint.setTextAlign(Paint.Align.CENTER);  mWarningTextPaint = new Paint(Paint.ANTI_ALIAS_FLAG);  mWarningTextPaint.setColor(mColors[1]);  font = Typeface.create("sans-serif", Typeface.BOLD);  mWarningTextPaint.setTypeface(font);  mWarningTextPaint.setTextAlign(Paint.Align.CENTER);  mChargeColor = getResources().getColor(R.color.batterymeter_charge_color);  mBoltPaint = new Paint();  mBoltPaint.setAntiAlias(true);  mBoltPaint.setColor(res.getColor(R.color.batterymeter_bolt_color));  mBoltPoints = loadBoltPoints(res);  setLayerType(View.LAYER_TYPE_SOFTWARE, null);
}  private static float[] loadBoltPoints(Resources res) {  final int[] pts = res.getIntArray(R.array.batterymeter_bolt_points);  int maxX = 0, maxY = 0;  for (int i = 0; i < pts.length; i += 2) {  maxX = Math.max(maxX, pts[i]);  maxY = Math.max(maxY, pts[i + 1]);  }  final float[] ptsF = new float[pts.length];  for (int i = 0; i < pts.length; i += 2) {  ptsF[i] = (float)pts[i] / maxX;  ptsF[i + 1] = (float)pts[i + 1] / maxY;  }  return ptsF;
}  @Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {  mHeight = h;  mWidth = w;  mWarningTextPaint.setTextSize(h * 0.75f);  mWarningTextHeight = -mWarningTextPaint.getFontMetrics().ascent;
}  private int getColorForLevel(int percent) {  int thresh, color = 0;  for (int i=0; i<mColors.length; i+=2) {  thresh = mColors[i];  color = mColors[i+1];  if (percent <= thresh) return color;  }  return color;
}  @Override
public void draw(Canvas c) {  //通过电池属性绘制图标  BatteryTracker tracker = mDemoMode ? mDemoTracker : mTracker;  final int level = tracker.level;  if (level == BatteryTracker.UNKNOWN_LEVEL) return;  float drawFrac = (float) level / 100f;  final int pt = getPaddingTop();  final int pl = getPaddingLeft();  final int pr = getPaddingRight();  final int pb = getPaddingBottom();  int height = mHeight - pt - pb;  int width = mWidth - pl - pr;  mButtonHeight = (int) (height * 0.12f);  mFrame.set(0, 0, width, height);  mFrame.offset(pl, pt);  mButtonFrame.set(  //这个就是电池图标上边的突起  mFrame.left + width * 0.25f,  mFrame.top,  mFrame.right - width * 0.25f,  mFrame.top + mButtonHeight + 5 /*cover frame border of intersecting area*/);  mButtonFrame.top += SUBPIXEL;  mButtonFrame.left += SUBPIXEL;  mButtonFrame.right -= SUBPIXEL;  mFrame.top += mButtonHeight; //电池图标桶装图  mFrame.left += SUBPIXEL;  mFrame.top += SUBPIXEL;  mFrame.right -= SUBPIXEL;  mFrame.bottom -= SUBPIXEL;  // first, draw the battery shape  c.drawRect(mFrame, mFramePaint);  // fill 'er up  final int color = tracker.plugged ? mChargeColor : getColorForLevel(level); //根据等级获取颜色，如果是15以下，就是红色。15以上是白色  mBatteryPaint.setColor(color);  if (level >= FULL) { //96时，电池图标里面填充完整，满电。  drawFrac = 1f;  } else if (level <= EMPTY) { //这个变量是说，当电量小于4的时候，电池图标里面没有填充色，空电量  drawFrac = 0f;  }  c.drawRect(mButtonFrame, drawFrac == 1f ? mBatteryPaint : mFramePaint);  mClipFrame.set(mFrame);  mClipFrame.top += (mFrame.height() * (1f - drawFrac));  c.save(Canvas.CLIP_SAVE_FLAG);  c.clipRect(mClipFrame);//在mFrame区域中保持mClipFrame的区域不变，参考下句注释  c.drawRect(mFrame, mBatteryPaint);//在mFrame中，把除去mClipFrame的区域绘制。（电量状态，如果是15以下，就是红色。15以上是白色）  c.restore();  if (tracker.plugged) { //这里就犀利了。这是说插上充电器就画一个闪电  // draw the bolt  final float bl = mFrame.left + mFrame.width() / 4.5f;  final float bt = mFrame.top + mFrame.height() / 6f;  final float br = mFrame.right - mFrame.width() / 7f;  final float bb = mFrame.bottom - mFrame.height() / 10f;  if (mBoltFrame.left != bl || mBoltFrame.top != bt  || mBoltFrame.right != br || mBoltFrame.bottom != bb) {  mBoltFrame.set(bl, bt, br, bb);  mBoltPath.reset();  mBoltPath.moveTo(  mBoltFrame.left + mBoltPoints[0] * mBoltFrame.width(),  mBoltFrame.top + mBoltPoints[1] * mBoltFrame.height());  for (int i = 2; i < mBoltPoints.length; i += 2) {  mBoltPath.lineTo(  mBoltFrame.left + mBoltPoints[i] * mBoltFrame.width(),  mBoltFrame.top + mBoltPoints[i + 1] * mBoltFrame.height());  }  mBoltPath.lineTo(  mBoltFrame.left + mBoltPoints[0] * mBoltFrame.width(),  mBoltFrame.top + mBoltPoints[1] * mBoltFrame.height());  }  c.drawPath(mBoltPath, mBoltPaint);  } else if (level <= EMPTY) { //这个是空电量的时候，画一个红色的感叹号  final float x = mWidth * 0.5f;  final float y = (mHeight + mWarningTextHeight) * 0.48f;  c.drawText(mWarningString, x, y, mWarningTextPaint);  } else if (mShowPercent && !(tracker.level == 100 && !SHOW_100_PERCENT)) { //以文字显示电量。不过这个没有用到（除非mShowPercent变量获取的配置属性为true）  mTextPaint.setTextSize(height *  (SINGLE_DIGIT_PERCENT ? 0.75f  : (tracker.level == 100 ? 0.38f : 0.5f)));  mTextHeight = -mTextPaint.getFontMetrics().ascent;  final String str = String.valueOf(SINGLE_DIGIT_PERCENT ? (level/10) : level);  final float x = mWidth * 0.5f;  final float y = (mHeight + mTextHeight) * 0.47f;  c.drawText(str,  x,  y,  mTextPaint);  }
}  private boolean mDemoMode;
private BatteryTracker mDemoTracker = new BatteryTracker();  @Override
public void dispatchDemoCommand(String command, Bundle args) {  if (!mDemoMode && command.equals(COMMAND_ENTER)) {  mDemoMode = true;  mDemoTracker.level = mTracker.level;  mDemoTracker.plugged = mTracker.plugged;  } else if (mDemoMode && command.equals(COMMAND_EXIT)) {  mDemoMode = false;  postInvalidate();  } else if (mDemoMode && command.equals(COMMAND_BATTERY)) {  String level = args.getString("level");  String plugged = args.getString("plugged");  if (level != null) {  mDemoTracker.level = Math.min(Math.max(Integer.parseInt(level), 0), 100);  }  if (plugged != null) {  mDemoTracker.plugged = Boolean.parseBoolean(plugged);  }  postInvalidate();  }
}

}
/*

Licensed under the Apache License, Version 2.0 (the “License”);
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an “AS IS” BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package com.android.systemui;

public static final boolean ENABLE_PERCENT = true;
public static final boolean SINGLE_DIGIT_PERCENT = false;
public static final boolean SHOW_100_PERCENT = false;public static final int FULL = 96;
public static final int EMPTY = 4;public static final float SUBPIXEL = 0.4f;  // inset rects for softer edgesint[] mColors;boolean mShowPercent = true;
Paint mFramePaint, mBatteryPaint, mWarningTextPaint, mTextPaint, mBoltPaint;
int mButtonHeight;
private float mTextHeight, mWarningTextHeight;private int mHeight;
private int mWidth;
private String mWarningString;
private final int mChargeColor;
private final float[] mBoltPoints;
private final Path mBoltPath = new Path();private final RectF mFrame = new RectF();
private final RectF mButtonFrame = new RectF();
private final RectF mClipFrame = new RectF();
private final RectF mBoltFrame = new RectF();private class BatteryTracker extends BroadcastReceiver {public static final int UNKNOWN_LEVEL = -1;// current battery statusint level = UNKNOWN_LEVEL;String percentStr;int plugType;boolean plugged;int health;int status;String technology;int voltage;int temperature;boolean testmode = false;@Overridepublic void onReceive(Context context, Intent intent) {final String action = intent.getAction();if (action.equals(Intent.ACTION_BATTERY_CHANGED)) { //接收电量改变的广播，取电池状态的属性if (testmode && ! intent.getBooleanExtra("testmode", false)) return;level = (int)(100f* intent.getIntExtra(BatteryManager.EXTRA_LEVEL, 0)/ intent.getIntExtra(BatteryManager.EXTRA_SCALE, 100));plugType = intent.getIntExtra(BatteryManager.EXTRA_PLUGGED, 0);plugged = plugType != 0;health = intent.getIntExtra(BatteryManager.EXTRA_HEALTH,BatteryManager.BATTERY_HEALTH_UNKNOWN);status = intent.getIntExtra(BatteryManager.EXTRA_STATUS,BatteryManager.BATTERY_STATUS_UNKNOWN);technology = intent.getStringExtra(BatteryManager.EXTRA_TECHNOLOGY);voltage = intent.getIntExtra(BatteryManager.EXTRA_VOLTAGE, 0);temperature = intent.getIntExtra(BatteryManager.EXTRA_TEMPERATURE, 0);setContentDescription(context.getString(R.string.accessibility_battery_level, level));postInvalidate();} else if (action.equals(ACTION_LEVEL_TEST)) {testmode = true;post(new Runnable() {int curLevel = 0;int incr = 1;int saveLevel = level;int savePlugged = plugType;Intent dummy = new Intent(Intent.ACTION_BATTERY_CHANGED);@Overridepublic void run() {if (curLevel < 0) {testmode = false;dummy.putExtra("level", saveLevel);dummy.putExtra("plugged", savePlugged);dummy.putExtra("testmode", false);} else {dummy.putExtra("level", curLevel);dummy.putExtra("plugged", incr > 0 ? BatteryManager.BATTERY_PLUGGED_AC : 0);dummy.putExtra("testmode", true);}getContext().sendBroadcast(dummy);if (!testmode) return;curLevel += incr;if (curLevel == 100) {incr *= -1;}postDelayed(this, 200);}});}}
}BatteryTracker mTracker = new BatteryTracker();@Override
public void onAttachedToWindow() {super.onAttachedToWindow();IntentFilter filter = new IntentFilter();filter.addAction(Intent.ACTION_BATTERY_CHANGED);filter.addAction(ACTION_LEVEL_TEST);final Intent sticky = getContext().registerReceiver(mTracker, filter);if (sticky != null) {// preload the battery levelmTracker.onReceive(getContext(), sticky);}
}@Override
public void onDetachedFromWindow() {super.onDetachedFromWindow();getContext().unregisterReceiver(mTracker);
}public BatteryMeterView(Context context) {this(context, null, 0);
}public BatteryMeterView(Context context, AttributeSet attrs) {this(context, attrs, 0);
}public BatteryMeterView(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);final Resources res = context.getResources();TypedArray levels = res.obtainTypedArray(R.array.batterymeter_color_levels);TypedArray colors = res.obtainTypedArray(R.array.batterymeter_color_values);final int N = levels.length();mColors = new int[2*N];for (int i=0; i<N; i++) {mColors[2*i] = levels.getInt(i, 0);mColors[2*i+1] = colors.getColor(i, 0);}levels.recycle();colors.recycle();mShowPercent = ENABLE_PERCENT && 0 != Settings.System.getInt(context.getContentResolver(), "status_bar_show_battery_percent", 0);mWarningString = context.getString(R.string.battery_meter_very_low_overlay_symbol);mFramePaint = new Paint(Paint.ANTI_ALIAS_FLAG);mFramePaint.setColor(res.getColor(R.color.batterymeter_frame_color));mFramePaint.setDither(true);mFramePaint.setStrokeWidth(0);mFramePaint.setStyle(Paint.Style.FILL_AND_STROKE);mFramePaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_ATOP));mBatteryPaint = new Paint(Paint.ANTI_ALIAS_FLAG);mBatteryPaint.setDither(true);mBatteryPaint.setStrokeWidth(0);mBatteryPaint.setStyle(Paint.Style.FILL_AND_STROKE);mTextPaint = new Paint(Paint.ANTI_ALIAS_FLAG);mTextPaint.setColor(0xFFFFFFFF);Typeface font = Typeface.create("sans-serif-condensed", Typeface.NORMAL);mTextPaint.setTypeface(font);mTextPaint.setTextAlign(Paint.Align.CENTER);mWarningTextPaint = new Paint(Paint.ANTI_ALIAS_FLAG);mWarningTextPaint.setColor(mColors[1]);font = Typeface.create("sans-serif", Typeface.BOLD);mWarningTextPaint.setTypeface(font);mWarningTextPaint.setTextAlign(Paint.Align.CENTER);mChargeColor = getResources().getColor(R.color.batterymeter_charge_color);mBoltPaint = new Paint();mBoltPaint.setAntiAlias(true);mBoltPaint.setColor(res.getColor(R.color.batterymeter_bolt_color));mBoltPoints = loadBoltPoints(res);setLayerType(View.LAYER_TYPE_SOFTWARE, null);
}private static float[] loadBoltPoints(Resources res) {final int[] pts = res.getIntArray(R.array.batterymeter_bolt_points);int maxX = 0, maxY = 0;for (int i = 0; i < pts.length; i += 2) {maxX = Math.max(maxX, pts[i]);maxY = Math.max(maxY, pts[i + 1]);}final float[] ptsF = new float[pts.length];for (int i = 0; i < pts.length; i += 2) {ptsF[i] = (float)pts[i] / maxX;ptsF[i + 1] = (float)pts[i + 1] / maxY;}return ptsF;
}@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {mHeight = h;mWidth = w;mWarningTextPaint.setTextSize(h * 0.75f);mWarningTextHeight = -mWarningTextPaint.getFontMetrics().ascent;
}private int getColorForLevel(int percent) {int thresh, color = 0;for (int i=0; i<mColors.length; i+=2) {thresh = mColors[i];color = mColors[i+1];if (percent <= thresh) return color;}return color;
}@Override
public void draw(Canvas c) {  //通过电池属性绘制图标BatteryTracker tracker = mDemoMode ? mDemoTracker : mTracker;final int level = tracker.level;if (level == BatteryTracker.UNKNOWN_LEVEL) return;float drawFrac = (float) level / 100f;final int pt = getPaddingTop();final int pl = getPaddingLeft();final int pr = getPaddingRight();final int pb = getPaddingBottom();int height = mHeight - pt - pb;int width = mWidth - pl - pr;mButtonHeight = (int) (height * 0.12f);mFrame.set(0, 0, width, height);mFrame.offset(pl, pt);mButtonFrame.set(  //这个就是电池图标上边的突起mFrame.left + width * 0.25f,mFrame.top,mFrame.right - width * 0.25f,mFrame.top + mButtonHeight + 5 /*cover frame border of intersecting area*/);mButtonFrame.top += SUBPIXEL;mButtonFrame.left += SUBPIXEL;mButtonFrame.right -= SUBPIXEL;mFrame.top += mButtonHeight; //电池图标桶装图mFrame.left += SUBPIXEL;mFrame.top += SUBPIXEL;mFrame.right -= SUBPIXEL;mFrame.bottom -= SUBPIXEL;// first, draw the battery shapec.drawRect(mFrame, mFramePaint);// fill 'er upfinal int color = tracker.plugged ? mChargeColor : getColorForLevel(level); //根据等级获取颜色，如果是15以下，就是红色。15以上是白色mBatteryPaint.setColor(color);if (level >= FULL) { //96时，电池图标里面填充完整，满电。drawFrac = 1f;} else if (level <= EMPTY) { //这个变量是说，当电量小于4的时候，电池图标里面没有填充色，空电量drawFrac = 0f;}c.drawRect(mButtonFrame, drawFrac == 1f ? mBatteryPaint : mFramePaint);mClipFrame.set(mFrame);mClipFrame.top += (mFrame.height() * (1f - drawFrac));c.save(Canvas.CLIP_SAVE_FLAG);c.clipRect(mClipFrame);//在mFrame区域中保持mClipFrame的区域不变，参考下句注释c.drawRect(mFrame, mBatteryPaint);//在mFrame中，把除去mClipFrame的区域绘制。（电量状态，如果是15以下，就是红色。15以上是白色）c.restore();if (tracker.plugged) { //这里就犀利了。这是说插上充电器就画一个闪电// draw the boltfinal float bl = mFrame.left + mFrame.width() / 4.5f;final float bt = mFrame.top + mFrame.height() / 6f;final float br = mFrame.right - mFrame.width() / 7f;final float bb = mFrame.bottom - mFrame.height() / 10f;if (mBoltFrame.left != bl || mBoltFrame.top != bt|| mBoltFrame.right != br || mBoltFrame.bottom != bb) {mBoltFrame.set(bl, bt, br, bb);mBoltPath.reset();mBoltPath.moveTo(mBoltFrame.left + mBoltPoints[0] * mBoltFrame.width(),mBoltFrame.top + mBoltPoints[1] * mBoltFrame.height());for (int i = 2; i < mBoltPoints.length; i += 2) {mBoltPath.lineTo(mBoltFrame.left + mBoltPoints[i] * mBoltFrame.width(),mBoltFrame.top + mBoltPoints[i + 1] * mBoltFrame.height());}mBoltPath.lineTo(mBoltFrame.left + mBoltPoints[0] * mBoltFrame.width(),mBoltFrame.top + mBoltPoints[1] * mBoltFrame.height());}c.drawPath(mBoltPath, mBoltPaint);} else if (level <= EMPTY) { //这个是空电量的时候，画一个红色的感叹号final float x = mWidth * 0.5f;final float y = (mHeight + mWarningTextHeight) * 0.48f;c.drawText(mWarningString, x, y, mWarningTextPaint);} else if (mShowPercent && !(tracker.level == 100 && !SHOW_100_PERCENT)) { //以文字显示电量。不过这个没有用到（除非mShowPercent变量获取的配置属性为true）mTextPaint.setTextSize(height *(SINGLE_DIGIT_PERCENT ? 0.75f: (tracker.level == 100 ? 0.38f : 0.5f)));mTextHeight = -mTextPaint.getFontMetrics().ascent;final String str = String.valueOf(SINGLE_DIGIT_PERCENT ? (level/10) : level);final float x = mWidth * 0.5f;final float y = (mHeight + mTextHeight) * 0.47f;c.drawText(str,x,y,mTextPaint);}
}private boolean mDemoMode;
private BatteryTracker mDemoTracker = new BatteryTracker();@Override
public void dispatchDemoCommand(String command, Bundle args) {if (!mDemoMode && command.equals(COMMAND_ENTER)) {mDemoMode = true;mDemoTracker.level = mTracker.level;mDemoTracker.plugged = mTracker.plugged;} else if (mDemoMode && command.equals(COMMAND_EXIT)) {mDemoMode = false;postInvalidate();} else if (mDemoMode && command.equals(COMMAND_BATTERY)) {String level = args.getString("level");String plugged = args.getString("plugged");if (level != null) {mDemoTracker.level = Math.min(Math.max(Integer.parseInt(level), 0), 100);}if (plugged != null) {mDemoTracker.plugged = Boolean.parseBoolean(plugged);}postInvalidate();}
}

}

总结：这个类就是绘制状态栏里面电量图标的自定义控件。

以上就是大概的逻辑，现总结，用于备忘

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