SystemUI中的PowerUI简析

PowerUI

powerUI是SystemUI显示电池相关信息的模块，包括低电量提醒，危急电量关机提醒，高温关机提醒，省电模式等的功能。
在powerUI.java 中主要是两个函数start()和onReveice()

启动流程

SystemUI启动时会加载众多功能模块，其中就包含着PowerUI，会直接调用\

PowerUI.start()

start() 函数是在PowerUI 中最先触发的方法。在方法内进行了一些赋值操作，及注册对电量变化和屏幕开闭状态的广播监听
1)实例化PowerManager，因为是处理和Power相关的业务，必须实例化PowerManager.

2)初始化关屏时间，关屏时间会持续刷新。

3)实例化PowerNotificationWarnings,Power相关的事件会通过Notification方式进行处理。

4)监控电池电量，在电量不足是给出警告和提示。

5)更新电池电量等级。

public void start() {//获取PowerManager  用于获取电池的相关信息mPowerManager = (PowerManager) mContext.getSystemService(Context.POWER_SERVICE);//获取自启动以来的毫秒数mScreenOffTime = mPowerManager.isScreenOn() ? -1 : SystemClock.elapsedRealtime();mWarnings = Dependency.get(WarningsUI.class);//和混合通知相关，相关功能平台默认是关闭的，我们暂时也就不关注了mEnhancedEstimates = Dependency.get(EnhancedEstimates.class);mLastConfiguration.setTo(mContext.getResources().getConfiguration());// 监测低电量阀值的改变ContentObserver obs = new ContentObserver(mHandler) {@Overridepublic void onChange(boolean selfChange) {updateBatteryWarningLevels();}};final ContentResolver resolver = mContext.getContentResolver();resolver.registerContentObserver(Settings.Global.getUriFor(Settings.Global.LOW_POWER_MODE_TRIGGER_LEVEL),false, obs, UserHandle.USER_ALL);// 更新低电量等阀值updateBatteryWarningLevels();// 监听相关广播mReceiver.init();//检查我们是否需要让用户知道手机之前因温度过高而关闭showWarnOnThermalShutdown();// Register an observer to configure mEnableSkinTemperatureWarning and perform the// registration of skin thermal event listener upon Settings change.//注册观察者以配置 mEnableSkinTemperatureWarning 并在设置更改时执行皮肤热事件侦听器的注册。resolver.registerContentObserver(Settings.Global.getUriFor(Settings.Global.SHOW_TEMPERATURE_WARNING),false /*notifyForDescendants*/,new ContentObserver(mHandler) {@Overridepublic void onChange(boolean selfChange) {doSkinThermalEventListenerRegistration();}});// Register an observer to configure mEnableUsbTemperatureAlarm and perform the// registration of usb thermal event listener upon Settings change.//注册观察者以配置 mEnableUsbTemperatureAlarm 并在设置更改时执行 USB 热事件侦听器的注册。resolver.registerContentObserver(Settings.Global.getUriFor(Settings.Global.SHOW_USB_TEMPERATURE_ALARM),false /*notifyForDescendants*/,new ContentObserver(mHandler) {@Overridepublic void onChange(boolean selfChange) {doUsbThermalEventListenerRegistration();}});// 初始化温度阀值initThermalEventListeners();mCommandQueue.addCallback(this);}

电池电量有三个关键值定义如下(frameworks\base\core\res\res\valuesconfig.xml):

<integer name="config_criticalBatteryWarningLevel">5</integer>

<integer name="config_lowBatteryWarningLevel">15</integer>

<integer name="config_lowBatteryCloseWarningBump">5</integer>

低电量警告

updateBatteryWarningLevels

void updateBatteryWarningLevels() {//获取系统配置的危急电量，默认值是5int critLevel = mContext.getResources().getInteger(com.android.internal.R.integer.config_criticalBatteryWarningLevel);// 获取系统配置的低电量值，默认：15int warnLevel = mContext.getResources().getInteger(com.android.internal.R.integer.config_lowBatteryWarningLevel);if (warnLevel < critLevel) {warnLevel = critLevel;}mLowBatteryReminderLevels[0] = warnLevel;mLowBatteryReminderLevels[1] = critLevel;// 获取系统配置的关闭低电量警告状态的电量值，默认：20（15+5）mLowBatteryAlertCloseLevel = mLowBatteryReminderLevels[0]+ mContext.getResources().getInteger(com.android.internal.R.integer.config_lowBatteryCloseWarningBump);}

电池相关广播监听

final class Receiver extends BroadcastReceiver {private boolean mHasReceivedBattery = false;public void init() {// Register for Intent broadcasts for...IntentFilter filter = new IntentFilter();// 省电模式改变filter.addAction(PowerManager.ACTION_POWER_SAVE_MODE_CHANGED);// 电池状态改变filter.addAction(Intent.ACTION_BATTERY_CHANGED);// 开关屏filter.addAction(Intent.ACTION_SCREEN_OFF);filter.addAction(Intent.ACTION_SCREEN_ON);// 切换用户filter.addAction(Intent.ACTION_USER_SWITCHED);mBroadcastDispatcher.registerReceiverWithHandler(this, filter, mHandler);// Force get initial values. Relying on Sticky behavior until API for getting info.if (!mHasReceivedBattery) {// Get initial stateIntent intent = mContext.registerReceiver(null,new IntentFilter(Intent.ACTION_BATTERY_CHANGED));if (intent != null) {onReceive(mContext, intent);}}}@Overridepublic void onReceive(Context context, Intent intent) {String action = intent.getAction();if (PowerManager.ACTION_POWER_SAVE_MODE_CHANGED.equals(action)) {ThreadUtils.postOnBackgroundThread(() -> {if (mPowerManager.isPowerSaveMode()) {// 开启省电模式则关闭低电量警告mWarnings.dismissLowBatteryWarning();}});} else if (Intent.ACTION_BATTERY_CHANGED.equals(action)) {mHasReceivedBattery = true;// 电量final int oldBatteryLevel = mBatteryLevel;mBatteryLevel = intent.getIntExtra(BatteryManager.EXTRA_LEVEL, 100);final int oldBatteryStatus = mBatteryStatus;mBatteryStatus = intent.getIntExtra(BatteryManager.EXTRA_STATUS,BatteryManager.BATTERY_STATUS_UNKNOWN);// 充电final int oldPlugType = mPlugType;mPlugType = intent.getIntExtra(BatteryManager.EXTRA_PLUGGED, 1);final int oldInvalidCharger = mInvalidCharger;mInvalidCharger = intent.getIntExtra(BatteryManager.EXTRA_INVALID_CHARGER, 0);mLastBatteryStateSnapshot = mCurrentBatteryStateSnapshot;final boolean plugged = mPlugType != 0;final boolean oldPlugged = oldPlugType != 0;// 根据当前电量与危急电量、低电量、关闭低电量警告电量比较判断当前所处状态int oldBucket = findBatteryLevelBucket(oldBatteryLevel);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);}// 更新电池警告信息mWarnings.update(mBatteryLevel, bucket, mScreenOffTime);if (oldInvalidCharger == 0 && mInvalidCharger != 0) {Slog.d(TAG, "showing invalid charger warning");mWarnings.showInvalidChargerWarning();return;} else if (oldInvalidCharger != 0 && mInvalidCharger == 0) {mWarnings.dismissInvalidChargerWarning();} else if (mWarnings.isInvalidChargerWarningShowing()) {// if invalid charger is showing, don't show low batteryif (DEBUG) {Slog.d(TAG, "Bad Charger");}return;}// Show the correct version of low battery warning if neededif (mLastShowWarningTask != null) {mLastShowWarningTask.cancel(true);if (DEBUG) {Slog.d(TAG, "cancelled task");}}mLastShowWarningTask = ThreadUtils.postOnBackgroundThread(() -> {// 判断是否要显示低电量警告maybeShowBatteryWarningV2(plugged, bucket);});} else if (Intent.ACTION_SCREEN_OFF.equals(action)) {mScreenOffTime = SystemClock.elapsedRealtime();} else if (Intent.ACTION_SCREEN_ON.equals(action)) {mScreenOffTime = -1;} else if (Intent.ACTION_USER_SWITCHED.equals(action)) {mWarnings.userSwitched();} else {Slog.w(TAG, "unknown intent: " + intent);}}}

protected void maybeShowBatteryWarningV2(boolean plugged, int bucket) {final boolean hybridEnabled = mEnhancedEstimates.isHybridNotificationEnabled();final boolean isPowerSaverMode = mPowerManager.isPowerSaveMode();// Stick current battery state into an immutable container to determine if we should show// a warning.if (DEBUG) {Slog.d(TAG, "evaluating which notification to show");}if (hybridEnabled) {if (DEBUG) {Slog.d(TAG, "using hybrid");}Estimate estimate = refreshEstimateIfNeeded();mCurrentBatteryStateSnapshot = new BatteryStateSnapshot(mBatteryLevel, isPowerSaverMode,plugged, bucket, mBatteryStatus, mLowBatteryReminderLevels[1],mLowBatteryReminderLevels[0], estimate.getEstimateMillis(),estimate.getAverageDischargeTime(),mEnhancedEstimates.getSevereWarningThreshold(),mEnhancedEstimates.getLowWarningThreshold(), estimate.isBasedOnUsage(),mEnhancedEstimates.getLowWarningEnabled());} else {if (DEBUG) {Slog.d(TAG, "using standard");}mCurrentBatteryStateSnapshot = new BatteryStateSnapshot(mBatteryLevel, isPowerSaverMode,plugged, bucket, mBatteryStatus, mLowBatteryReminderLevels[1],mLowBatteryReminderLevels[0]);}mWarnings.updateSnapshot(mCurrentBatteryStateSnapshot);if (mCurrentBatteryStateSnapshot.isHybrid()) {maybeShowHybridWarning(mCurrentBatteryStateSnapshot, mLastBatteryStateSnapshot);} else {maybeShowBatteryWarning(mCurrentBatteryStateSnapshot, mLastBatteryStateSnapshot);}}protected void maybeShowBatteryWarning(BatteryStateSnapshot currentSnapshot,BatteryStateSnapshot lastSnapshot) {final boolean playSound = currentSnapshot.getBucket() != lastSnapshot.getBucket()|| lastSnapshot.getPlugged();if (shouldShowLowBatteryWarning(currentSnapshot, lastSnapshot)) {mWarnings.showLowBatteryWarning(playSound);} else if (shouldDismissLowBatteryWarning(currentSnapshot, lastSnapshot)) {mWarnings.dismissLowBatteryWarning();} else {mWarnings.updateLowBatteryWarning();}}

在ACTION_SCREEN_OFF、ACTION_SCREEN_ON这两个广播事件处理中只是简单的对 mScreenOffTime 进行了重新赋值，当屏幕关闭时设置为从系统启动到现在的时间，当屏幕开启时设置为 -1。该值用于在其他位置做差值判断如播放低电量声音时是否播放。

      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"); // 屏幕休眠时间太久了，不使用低电量声音唤醒使用者return;}

ACTION_BATTERY_CHANGED 广播

final int oldBatteryLevel = mBatteryLevel;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); int bucket = findBatteryLevelBucket(mBatteryLevel); // 获取电量等级判断