基于Android Q的电池服务分析之充电类型判断

开局先说明一下我的需求和我遇到的难题

问题

插入充电没有提示音和图标更新
插入充电没有任何反应和提示，但是确实是在充电

需求

在设置的电池中增加充电类型判断并显示在UI上

1.造成问题的原因

驱动online节点无法正常读取，导致上层数据为空，造成的bug
涉及到的内容：
1.BatteryService.java
这里接收了health层发来的数据：充电广播，记录充电状态，低电量，电池高温，充电方式;发送充电广播产生充电提示音和更新充电图标2.HealthInfo层
上层注册health服务，底层调用#healthd_battery_update，回调给上层（BatteryService）的update方法，回调过来以后携带了充电的一系列数据（包括充电方式）3.health_common.cpp
healthd_battery_update方法：用于间接回调到上层的update，它还要调用到BatteryMonitor#BatteryMonitor::update(void)4.BatteryMonitor.cpp
bool BatteryMonitor::update(void)方法去完成实际意义上的更新，从health_common.cpp#
static void healthd_battery_update(void) {Health::getImplementation()->update();
}
调用到这里。

2.整体运行流程分析

先来看一张流程图
从kernel层和HAL层开始调用.那我们先从BatteryServer.java分析

2.1 BatteryService.java

该类继承了SystemService，是属于一个系统服务，所以当它服务被监听时，每次onStart会一直被回调执行，直接上代码

  @Overridepublic void onStart() {//注册Health并执行回调结果，Health是底层的一个对电池状态监听和获取电池信息的重要层级registerHealthCallback();//实例化自身mBinderService = new BinderService();//注册本身的服务publishBinderService("battery", mBinderService);//注册电池监听，当底层电池电量发生变化调用此监听，并调用update。mBatteryPropertiesRegistrar = new BatteryPropertiesRegistrar();//注册到Binder服务端publishBinderService("batteryproperties", mBatteryPropertiesRegistrar);//注册到本地服务publishLocalService(BatteryManagerInternal.class, new LocalService());}

可以看到主要工作是做了一些服务的注册，最重要的就是registerHealthCallback()和BinderService()

2.1.1 registerHealthCallback

 private void registerHealthCallback() {traceBegin("HealthInitWrapper");mHealthServiceWrapper = new HealthServiceWrapper();//第一步mHealthHalCallback = new HealthHalCallback();//第二步// IHealth is lazily retrieved.try {mHealthServiceWrapper.init(mHealthHalCallback,new HealthServiceWrapper.IServiceManagerSupplier() {},new HealthServiceWrapper.IHealthSupplier() {});} catch (RemoteException ex) {Slog.e(TAG, "health: cannot register callback. (RemoteException)");throw ex.rethrowFromSystemServer();} catch (NoSuchElementException ex) {Slog.e(TAG, "health: cannot register callback. (no supported health HAL service)");throw ex;} finally {traceEnd();}traceBegin("HealthInitWaitUpdate");...}

看到第一步：该方法是来确定要使用的Health服务实例(来自vender的“default”实例或来自healthd的“backup”实例)。然后通过IHealth.registerCallback监听取Health事件，做一些init操作，注册相应的关系。这里对这个暂不深究

第二步：HealthHalCallback()是一个非常关键的回调，用于将Health层的数据回调到framework层，包含了电池的大部分信息（电池充电状态，等），接着进入该方法，看看主要逻辑

2.1.2 HealthHalCallback

该类继承了HealthInfoCallback.Stub，用AIDL跨进程方式去对电池信息做回调动作，所以在这里看不见JNI的东西，另外插个话 监听电池电量变化是用广播(ACTION_BATTERY_CHANGED BATTERY_CHANGED )形式发送给{@link android.content.BroadcastReceiver IntentReceivers}这类的服务。

 private final class HealthHalCallback extends IHealthInfoCallback.Stubimplements HealthServiceWrapper.Callback {@Override public void healthInfoChanged(android.hardware.health.V2_0.HealthInfo props) {BatteryService.this.update(props);//Health层回调数据给上层，用广播形式通知到上层}// on new service registered@Override public void onRegistration(IHealth oldService, IHealth newService,String instance) {if (newService == null) return;traceBegin("HealthUnregisterCallback");try {if (oldService != null) {int r = oldService.unregisterCallback(this);if (r != Result.SUCCESS) {Slog.w(TAG, "health: cannot unregister previous callback: " +Result.toString(r));}}} catch (RemoteException ex) {Slog.w(TAG, "health: cannot unregister previous callback (transaction error): "+ ex.getMessage());} finally {traceEnd();}traceBegin("HealthRegisterCallback");try {int r = newService.registerCallback(this);if (r != Result.SUCCESS) {Slog.w(TAG, "health: cannot register callback: " + Result.toString(r));return;}// registerCallback does NOT guarantee that update is called// immediately, so request a manual update here.newService.update();//电池数据回调} catch (RemoteException ex) {Slog.e(TAG, "health: cannot register callback (transaction error): "+ ex.getMessage());} finally {traceEnd();}}}

这里主要看的就是update()方法，接着往下看

2.1.3 update

该方法就是Health层通过发起广播，执行跨进程事件，回调到上层来的数据，先看代码

private void update(android.hardware.health.V2_0.HealthInfo info) {...  synchronized (mLock) {if (!mUpdatesStopped) {// 将数据拿到赋值给mHealthInfomHealthInfo = info.legacy;// Process the new values.// 处理mHealthInfo的主要实现方法processValuesLocked(false);mLock.notifyAll(); // for any waiters on new info} else {copy(mLastHealthInfo, info.legacy);}}...}

2.1.4 processValuesLocked

该方法很长，包含了充电类型判断，电量低时的广播，插入充电/拔出充电的广播，LED灯闪烁等功能

所以直接上代码，在注释里看解释

private void processValuesLocked(boolean force) {boolean logOutlier = false;long dischargeDuration = 0;//获取电池电量是否低于critical界限mBatteryLevelCritical =mHealthInfo.batteryStatus != BatteryManager.BATTERY_STATUS_UNKNOWN&& mHealthInfo.batteryLevel <= mCriticalBatteryLevel;//判断是AC/USB/WLC中的哪一种充电方式if (mHealthInfo.chargerAcOnline) {mPlugType = BatteryManager.BATTERY_PLUGGED_AC;} else if (mHealthInfo.chargerUsbOnline) {mPlugType = BatteryManager.BATTERY_PLUGGED_USB;} else if (mHealthInfo.chargerWirelessOnline) {mPlugType = BatteryManager.BATTERY_PLUGGED_WIRELESS;} else {mPlugType = BATTERY_PLUGGED_NONE;}if (DEBUG) {Slog.d(TAG, "Processing new values: "+ "info=" + mHealthInfo+ ", mBatteryLevelCritical=" + mBatteryLevelCritical+ ", mPlugType=" + mPlugType);}// Let the battery stats keep track of the current level.try {mBatteryStats.setBatteryState(mHealthInfo.batteryStatus, mHealthInfo.batteryHealth,mPlugType, mHealthInfo.batteryLevel, mHealthInfo.batteryTemperature,mHealthInfo.batteryVoltage, mHealthInfo.batteryChargeCounter,mHealthInfo.batteryFullCharge);} catch (RemoteException e) {// Should never happen.}//低电量关机shutdownIfNoPowerLocked();//电池温度过高关机shutdownIfOverTempLocked();//force是第一次调用时标志，如果状态有更改依然会调用下面的代码if (force || (mHealthInfo.batteryStatus != mLastBatteryStatus ||mHealthInfo.batteryHealth != mLastBatteryHealth ||mHealthInfo.batteryPresent != mLastBatteryPresent ||mHealthInfo.batteryLevel != mLastBatteryLevel ||mPlugType != mLastPlugType ||mHealthInfo.batteryVoltage != mLastBatteryVoltage ||mHealthInfo.batteryTemperature != mLastBatteryTemperature ||mHealthInfo.maxChargingCurrent != mLastMaxChargingCurrent ||mHealthInfo.maxChargingVoltage != mLastMaxChargingVoltage ||mHealthInfo.batteryChargeCounter != mLastChargeCounter ||mInvalidCharger != mLastInvalidCharger)) {//插入状态有更改，mLastPlugType是记录上一次充电方式，mPlugType是当前充电方式if (mPlugType != mLastPlugType) {if (mLastPlugType == BATTERY_PLUGGED_NONE) {//没充电状态到充电状态// discharging -> chargingmChargeStartLevel = mHealthInfo.batteryLevel;mChargeStartTime = SystemClock.elapsedRealtime();final LogMaker builder = new LogMaker(MetricsEvent.ACTION_CHARGE);builder.setType(MetricsEvent.TYPE_ACTION);builder.addTaggedData(MetricsEvent.FIELD_PLUG_TYPE, mPlugType);builder.addTaggedData(MetricsEvent.FIELD_BATTERY_LEVEL_START,mHealthInfo.batteryLevel);mMetricsLogger.write(builder);// 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 != mHealthInfo.batteryLevel) {dischargeDuration = SystemClock.elapsedRealtime() - mDischargeStartTime;logOutlier = true;EventLog.writeEvent(EventLogTags.BATTERY_DISCHARGE, dischargeDuration,mDischargeStartLevel, mHealthInfo.batteryLevel);// make sure we see a discharge event before logging againmDischargeStartTime = 0;}} else if (mPlugType == BATTERY_PLUGGED_NONE) {//充电状态到未充电状态 或者开机上电// charging -> discharging or we just powered upmDischargeStartTime = SystemClock.elapsedRealtime();mDischargeStartLevel = mHealthInfo.batteryLevel;long chargeDuration = SystemClock.elapsedRealtime() - mChargeStartTime;if (mChargeStartTime != 0 && chargeDuration != 0) {final LogMaker builder = new LogMaker(MetricsEvent.ACTION_CHARGE);builder.setType(MetricsEvent.TYPE_DISMISS);builder.addTaggedData(MetricsEvent.FIELD_PLUG_TYPE, mLastPlugType);builder.addTaggedData(MetricsEvent.FIELD_CHARGING_DURATION_MILLIS,chargeDuration);builder.addTaggedData(MetricsEvent.FIELD_BATTERY_LEVEL_START,mChargeStartLevel);builder.addTaggedData(MetricsEvent.FIELD_BATTERY_LEVEL_END,mHealthInfo.batteryLevel);mMetricsLogger.write(builder);}mChargeStartTime = 0;}}// 电池状态更新if (mHealthInfo.batteryStatus != mLastBatteryStatus ||mHealthInfo.batteryHealth != mLastBatteryHealth ||mHealthInfo.batteryPresent != mLastBatteryPresent ||mPlugType != mLastPlugType) {EventLog.writeEvent(EventLogTags.BATTERY_STATUS,mHealthInfo.batteryStatus, mHealthInfo.batteryHealth, mHealthInfo.batteryPresent ? 1 : 0,mPlugType, mHealthInfo.batteryTechnology);}// 电池电量更新if (mHealthInfo.batteryLevel != mLastBatteryLevel) {// Don't do this just from voltage or temperature changes, that is// too noisy.EventLog.writeEvent(EventLogTags.BATTERY_LEVEL,mHealthInfo.batteryLevel, mHealthInfo.batteryVoltage, mHealthInfo.batteryTemperature);}// 记录电池快没电状态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;}//电量低时是否切换到低电量模式if (!mBatteryLevelLow) {// Should we now switch in to low battery mode?if (mPlugType == BATTERY_PLUGGED_NONE&& mHealthInfo.batteryStatus !=BatteryManager.BATTERY_STATUS_UNKNOWN&& mHealthInfo.batteryLevel <= mLowBatteryWarningLevel) {mBatteryLevelLow = true;}} else {// Should we now switch out of low battery mode?if (mPlugType != BATTERY_PLUGGED_NONE) {mBatteryLevelLow = false;} else if (mHealthInfo.batteryLevel >= mLowBatteryCloseWarningLevel)  {mBatteryLevelLow = false;} else if (force && mHealthInfo.batteryLevel >= mLowBatteryWarningLevel) {// If being forced, the previous state doesn't matter, we will just// absolutely check to see if we are now above the warning level.mBatteryLevelLow = false;}}mSequence++;// 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.//插入充电时，发送广播，播放提示音和更新充电UIif (mPlugType != 0 && mLastPlugType == 0) {final Intent statusIntent = new Intent(Intent.ACTION_POWER_CONNECTED);statusIntent.setFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT);statusIntent.putExtra(BatteryManager.EXTRA_SEQUENCE, mSequence);mHandler.post(new Runnable() {@Overridepublic void run() {mContext.sendBroadcastAsUser(statusIntent, UserHandle.ALL);}});}//断开充电时，发送广播，播放提示音和更新充电UIelse if (mPlugType == 0 && mLastPlugType != 0) {final Intent statusIntent = new Intent(Intent.ACTION_POWER_DISCONNECTED);statusIntent.setFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT);statusIntent.putExtra(BatteryManager.EXTRA_SEQUENCE, mSequence);mHandler.post(new Runnable() {@Overridepublic void run() {mContext.sendBroadcastAsUser(statusIntent, UserHandle.ALL);}});}// 低电量电池事件通知if (shouldSendBatteryLowLocked()) {mSentLowBatteryBroadcast = true;final Intent statusIntent = new Intent(Intent.ACTION_BATTERY_LOW);statusIntent.setFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT);statusIntent.putExtra(BatteryManager.EXTRA_SEQUENCE, mSequence);mHandler.post(new Runnable() {@Overridepublic void run() {mContext.sendBroadcastAsUser(statusIntent, UserHandle.ALL);}});} else if (mSentLowBatteryBroadcast &&mHealthInfo.batteryLevel >= mLowBatteryCloseWarningLevel) {mSentLowBatteryBroadcast = false;final Intent statusIntent = new Intent(Intent.ACTION_BATTERY_OKAY);statusIntent.setFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY_BEFORE_BOOT);statusIntent.putExtra(BatteryManager.EXTRA_SEQUENCE, mSequence);mHandler.post(new Runnable() {@Overridepublic void run() {mContext.sendBroadcastAsUser(statusIntent, UserHandle.ALL);}});}//当以上的广播完成后，该方法主要用于记录mHealthInfo的状态信息，就是电池的一些状态+电池是否充电的信息+电量等信息//发送粘性广播给everyonesendBatteryChangedIntentLocked();if (mLastBatteryLevel != mHealthInfo.batteryLevel || mLastPlugType != mPlugType) {sendBatteryLevelChangedIntentLocked();}//更新Led灯信息mLed.updateLightsLocked();// This needs to be done after sendIntent() so that we get the lastest battery stats.if (logOutlier && dischargeDuration != 0) {logOutlierLocked(dischargeDuration);}//记录上一次mHealthInfo的状态mLastBatteryStatus = mHealthInfo.batteryStatus;mLastBatteryHealth = mHealthInfo.batteryHealth;mLastBatteryPresent = mHealthInfo.batteryPresent;mLastBatteryLevel = mHealthInfo.batteryLevel;mLastPlugType = mPlugType;mLastBatteryVoltage = mHealthInfo.batteryVoltage;mLastBatteryTemperature = mHealthInfo.batteryTemperature;mLastMaxChargingCurrent = mHealthInfo.maxChargingCurrent;mLastMaxChargingVoltage = mHealthInfo.maxChargingVoltage;mLastChargeCounter = mHealthInfo.batteryChargeCounter;mLastBatteryLevelCritical = mBatteryLevelCritical;mLastInvalidCharger = mInvalidCharger;}}

可以看到如果插入充电没有提示音，在这代码中，一定是广播没有发送出去（当然不排除广播发出去了，充电提示语那块代码有问题），我遇到的问题就是没有充电提示音+没有充电提示图标，就是广播没执行到，为什么广播没执行到，主要是因为if语句不满足，而满足if语句的条件就是需要读取当前是哪种充电方式，而我的问题是读取不到充电方式，导致的广播未发送

上层已经大概的分析完了，接下来看底层

2.2 healthd_common.cpp

统一的从main方法开始执行

2.2.1 healthd_main

int healthd_main() {int ret;klog_set_level(KLOG_LEVEL);if (!healthd_mode_ops) {KLOG_ERROR("healthd ops not set, exiting\n");exit(1);}ret = healthd_init();if (ret) {KLOG_ERROR("Initialization failed, exiting\n");exit(2);}healthd_mainloop();KLOG_ERROR("Main loop terminated, exiting\n");return 3;
}

从main方法开始，调用healthd_init()和healthd_mainloop()进行初始化和无限循环，还记得开局的那张图吧？其中就有这两个方法，mainloop主要作用于循环监听kernel层的电量改变并读取电量信息，这里不关注内部怎么读取的；init主要实例化了BatteryMonitor并调用了它的init函数；先接着看

2.2.2 healthd_battery_update

该方法会调用BatteryMonitor.cpp中的bool BatteryMonitor::update(void)，主要怎么去读取电量信息，读取电量状态的实现都在这update里面

static void healthd_battery_update(void) {Health::getImplementation()->update();
}

调用了Health::getImplementation()->update()后会回调给上层，那接着就要走到BatteryMonitor.cpp中了

2.3 BatteryMonitor.cpp

直接走到init方法里看看，因为在第2.1（main函数）中执行了该类的init方法

2.3.1 void BatteryMonitor::init()

void BatteryMonitor::init(struct healthd_config *hc) {String8 path;char pval[PROPERTY_VALUE_MAX];mHealthdConfig = hc;std::unique_ptr<DIR, decltype(&closedir)> dir(opendir(POWER_SUPPLY_SYSFS_PATH), closedir);if (dir == NULL) {KLOG_ERROR(LOG_TAG, "Could not open %s\n", POWER_SUPPLY_SYSFS_PATH);} else {struct dirent* entry;while ((entry = readdir(dir.get()))) {const char* name = entry->d_name;std::vector<String8>::iterator itIgnoreName;if (!strcmp(name, ".") || !strcmp(name, ".."))continue;itIgnoreName = find(hc->ignorePowerSupplyNames.begin(),hc->ignorePowerSupplyNames.end(), String8(name));if (itIgnoreName != hc->ignorePowerSupplyNames.end())continue;// Look for "type" file in each subdirectorypath.clear();path.appendFormat("%s/%s/type", POWER_SUPPLY_SYSFS_PATH, name);switch(readPowerSupplyType(path)) {case ANDROID_POWER_SUPPLY_TYPE_AC:case ANDROID_POWER_SUPPLY_TYPE_USB:case ANDROID_POWER_SUPPLY_TYPE_WIRELESS:path.clear();path.appendFormat("%s/%s/online", POWER_SUPPLY_SYSFS_PATH, name);if (access(path.string(), R_OK) == 0)mChargerNames.add(String8(name));break;case ANDROID_POWER_SUPPLY_TYPE_BATTERY:mBatteryDevicePresent = true;if (mHealthdConfig->batteryStatusPath.isEmpty()) {path.clear();path.appendFormat("%s/%s/status", POWER_SUPPLY_SYSFS_PATH,name);if (access(path, R_OK) == 0)mHealthdConfig->batteryStatusPath = path;}if (mHealthdConfig->batteryHealthPath.isEmpty()) {path.clear();path.appendFormat("%s/%s/health", POWER_SUPPLY_SYSFS_PATH,name);if (access(path, R_OK) == 0)mHealthdConfig->batteryHealthPath = path;}if (mHealthdConfig->batteryPresentPath.isEmpty()) {path.clear();path.appendFormat("%s/%s/present", POWER_SUPPLY_SYSFS_PATH,name);if (access(path, R_OK) == 0)mHealthdConfig->batteryPresentPath = path;}if (mHealthdConfig->batteryCapacityPath.isEmpty()) {path.clear();path.appendFormat("%s/%s/capacity", POWER_SUPPLY_SYSFS_PATH,name);if (access(path, R_OK) == 0)mHealthdConfig->batteryCapacityPath = path;}if (mHealthdConfig->batteryVoltagePath.isEmpty()) {path.clear();path.appendFormat("%s/%s/voltage_now",POWER_SUPPLY_SYSFS_PATH, name);if (access(path, R_OK) == 0) {mHealthdConfig->batteryVoltagePath = path;}else {path.clear();path.appendFormat("%s/%s/batt_vol",POWER_SUPPLY_SYSFS_PATH, name);if (access(path, R_OK) == 0)mHealthdConfig->batteryVoltagePath = path;}   }   if (mHealthdConfig->batteryFullChargePath.isEmpty()) {path.clear();path.appendFormat("%s/%s/charge_full",POWER_SUPPLY_SYSFS_PATH, name);if (access(path, R_OK) == 0)mHealthdConfig->batteryFullChargePath = path;}if (mHealthdConfig->batteryCurrentNowPath.isEmpty()) {path.clear();path.appendFormat("%s/%s/current_now",POWER_SUPPLY_SYSFS_PATH, name);if (access(path, R_OK) == 0)mHealthdConfig->batteryCurrentNowPath = path;}if (mHealthdConfig->batteryCycleCountPath.isEmpty()) {path.clear();path.appendFormat("%s/%s/cycle_count",POWER_SUPPLY_SYSFS_PATH, name);if (access(path, R_OK) == 0)mHealthdConfig->batteryCycleCountPath = path;}if (mHealthdConfig->batteryCurrentAvgPath.isEmpty()) {path.clear();path.appendFormat("%s/%s/current_avg",POWER_SUPPLY_SYSFS_PATH, name);if (access(path, R_OK) == 0)mHealthdConfig->batteryCurrentAvgPath = path;}if (mHealthdConfig->batteryChargeCounterPath.isEmpty()) {path.clear();path.appendFormat("%s/%s/charge_counter",POWER_SUPPLY_SYSFS_PATH, name);if (access(path, R_OK) == 0)mHealthdConfig->batteryChargeCounterPath = path;}if (mHealthdConfig->batteryTemperaturePath.isEmpty()) {path.clear();path.appendFormat("%s/%s/temp", POWER_SUPPLY_SYSFS_PATH,name);if (access(path, R_OK) == 0) {mHealthdConfig->batteryTemperaturePath = path;}else {path.clear();path.appendFormat("%s/%s/batt_temp",POWER_SUPPLY_SYSFS_PATH, name);if (access(path, R_OK) == 0)mHealthdConfig->batteryTemperaturePath = path;}}if (mHealthdConfig->batteryTechnologyPath.isEmpty()) {path.clear();path.appendFormat("%s/%s/technology",POWER_SUPPLY_SYSFS_PATH, name);if (access(path, R_OK) == 0)mHealthdConfig->batteryTechnologyPath = path;}break;case ANDROID_POWER_SUPPLY_TYPE_UNKNOWN:break;}}}...
}

init方法主要实现了读取电池信息的一些列节点，online ,status,type,charge_counter,voltage_now …

先看上面的这段代码

 path.clear();path.appendFormat("%s/%s/type", POWER_SUPPLY_SYSFS_PATH, name);switch(readPowerSupplyType(path)) {case ANDROID_POWER_SUPPLY_TYPE_AC:case ANDROID_POWER_SUPPLY_TYPE_USB:case ANDROID_POWER_SUPPLY_TYPE_WIRELESS:path.clear();path.appendFormat("%s/%s/online", POWER_SUPPLY_SYSFS_PATH, name);if (access(path.string(), R_OK) == 0)mChargerNames.add(String8(name));break;

循环遍历父目录下的type和online节点，三种充电类型的数据都写入mChargerNames，初始化完毕了，那就看update

2.3.2 bool BatteryMonitor::update(void)

bool BatteryMonitor::update(void) {bool logthis;initBatteryProperties(&props);if (!mHealthdConfig->batteryPresentPath.isEmpty())props.batteryPresent = getBooleanField(mHealthdConfig->batteryPresentPath);elseprops.batteryPresent = mBatteryDevicePresent;
//根据初始化后的数据，来读取电池信息的信息 beginprops.batteryLevel = mBatteryFixedCapacity ?mBatteryFixedCapacity :getIntField(mHealthdConfig->batteryCapacityPath);props.batteryVoltage = getIntField(mHealthdConfig->batteryVoltagePath) / 1000;if (!mHealthdConfig->batteryCurrentNowPath.isEmpty())props.batteryCurrent = getIntField(mHealthdConfig->batteryCurrentNowPath) / 1000;if (!mHealthdConfig->batteryFullChargePath.isEmpty())props.batteryFullCharge = getIntField(mHealthdConfig->batteryFullChargePath);if (!mHealthdConfig->batteryCycleCountPath.isEmpty())props.batteryCycleCount = getIntField(mHealthdConfig->batteryCycleCountPath);if (!mHealthdConfig->batteryChargeCounterPath.isEmpty())props.batteryChargeCounter = getIntField(mHealthdConfig->batteryChargeCounterPath);props.batteryTemperature = mBatteryFixedTemperature ?mBatteryFixedTemperature :getIntField(mHealthdConfig->batteryTemperaturePath);std::string buf;if (readFromFile(mHealthdConfig->batteryStatusPath, &buf) > 0)props.batteryStatus = getBatteryStatus(buf.c_str());if (readFromFile(mHealthdConfig->batteryHealthPath, &buf) > 0)props.batteryHealth = getBatteryHealth(buf.c_str());if (readFromFile(mHealthdConfig->batteryTechnologyPath, &buf) > 0)props.batteryTechnology = String8(buf.c_str());double MaxPower = 0;
//根据初始化后的数据，来读取电池信息的信息 end//根据初始化，我特意提到的片段代码中的mChargerNamesfor (size_t i = 0; i < mChargerNames.size(); i++) {String8 path;//循环遍历三种充电类型的online节点，0：未使用该类型充电，1：使用的是该类型充电path.appendFormat("%s/%s/online", POWER_SUPPLY_SYSFS_PATH,mChargerNames[i].string());if (getIntField(path)) {path.clear();path.appendFormat("%s/%s/type", POWER_SUPPLY_SYSFS_PATH,mChargerNames[i].string());switch(readPowerSupplyType(path)) {case ANDROID_POWER_SUPPLY_TYPE_AC:props.chargerAcOnline = true;break;case ANDROID_POWER_SUPPLY_TYPE_USB:props.chargerUsbOnline = true;break;case ANDROID_POWER_SUPPLY_TYPE_WIRELESS:props.chargerWirelessOnline = true;break;default:KLOG_WARNING(LOG_TAG, "%s: Unknown power supply type\n",mChargerNames[i].string());}// 上面会根据是哪种充电类型case进行赋值true，主要方法是readPowerSupplyType，它根据type节点，去得到数据匹配对应的case//如果是WLC充电，则其余充电置falsepath.clear();path.appendFormat("%s", WLC_51025_STATUS);if(getIntField(path)){props.chargerWirelessOnline = true;props.chargerAcOnline = false;props.chargerUsbOnline = false;}//获取当前最大电量,电压等信息path.clear();path.appendFormat("%s/%s/current_max", POWER_SUPPLY_SYSFS_PATH,mChargerNames[i].string());int ChargingCurrent =(access(path.string(), R_OK) == 0) ? getIntField(path) : 0;path.clear();path.appendFormat("%s/%s/voltage_max", POWER_SUPPLY_SYSFS_PATH,mChargerNames[i].string());int ChargingVoltage =(access(path.string(), R_OK) == 0) ? getIntField(path) :DEFAULT_VBUS_VOLTAGE;double power = ((double)ChargingCurrent / MILLION) *((double)ChargingVoltage / MILLION);if (MaxPower < power) {props.maxChargingCurrent = ChargingCurrent;props.maxChargingVoltage = ChargingVoltage;MaxPower = power;}}}...// 获取到以上信息后，更新电池状态 healthd_mode_ops->battery_update(&props);// 返回电池是否处在充电状态return props.chargerAcOnline | props.chargerUsbOnline |props.chargerWirelessOnline;
}

一切都在注释里，这个方法主要是获取到电量的信息，状态，电压，电量等…刚刚提到了readPowerSupplyType，这里我们接着看一下

2.3.3 readPowerSupplyType

该方法根据type节点去获取数据，匹配对应的case

BatteryMonitor::PowerSupplyType BatteryMonitor::readPowerSupplyType(const String8& path) {std::string buf;int ret;// 根据Key去赋值valuestruct sysfsStringEnumMap supplyTypeMap[] = {{ "Unknown", ANDROID_POWER_SUPPLY_TYPE_UNKNOWN },{ "Battery", ANDROID_POWER_SUPPLY_TYPE_BATTERY },{ "UPS", ANDROID_POWER_SUPPLY_TYPE_AC },{ "Mains", ANDROID_POWER_SUPPLY_TYPE_AC },{ "USB", ANDROID_POWER_SUPPLY_TYPE_USB },{ "USB_DCP", ANDROID_POWER_SUPPLY_TYPE_AC },{ "USB_HVDCP", ANDROID_POWER_SUPPLY_TYPE_AC },{ "USB_CDP", ANDROID_POWER_SUPPLY_TYPE_AC },{ "USB_ACA", ANDROID_POWER_SUPPLY_TYPE_AC },{ "USB_C", ANDROID_POWER_SUPPLY_TYPE_AC },{ "USB_PD", ANDROID_POWER_SUPPLY_TYPE_AC },{ "USB_PD_DRP", ANDROID_POWER_SUPPLY_TYPE_USB },{ "Wireless", ANDROID_POWER_SUPPLY_TYPE_WIRELESS },{ NULL, 0 },};//读取传入的path路径if (readFromFile(path, &buf) <= 0)return ANDROID_POWER_SUPPLY_TYPE_UNKNOWN;//拿到读取的数据转换为stringret = mapSysfsString(buf.c_str(), supplyTypeMap);if (ret < 0) {KLOG_WARNING(LOG_TAG, "Unknown power supply type '%s'\n", buf.c_str());ret = ANDROID_POWER_SUPPLY_TYPE_UNKNOWN;}// 返回对应的结构体，例如“USB” 就返回 ANDROID_POWER_SUPPLY_TYPE_USBreturn static_cast<BatteryMonitor::PowerSupplyType>(ret);
}

此时整个流程就算完毕了，就回到了2.2，2.2又回调到上层的2.1.3了

3.解决问题的方法

我的问题是在设置中显示充电类型，AC/USB/OTG充电类型等

Framework # Utils.java

public static String getBatteryStatus(Resources res, Intent batteryChangedIntent) {int status = batteryChangedIntent.getIntExtra(BatteryManager.EXTRA_STATUS,BatteryManager.BATTERY_STATUS_UNKNOWN);//第一步String statusString;//第二步if (status == BatteryManager.BATTERY_STATUS_CHARGING) {statusString = res.getString(R.string.battery_info_status_charging);//show charge type by software UI，beginint plugType = batteryChangedIntent.getIntExtra(BatteryManager.EXTRA_PLUGGED, 0);int plugTypeStringId = 0;if (plugType ==BatteryManager.BATTERY_PLUGGED_AC) {plugTypeStringId = R.string.battery_info_plug_type_ac;}else if (plugType ==BatteryManager.BATTERY_PLUGGED_USB) {plugTypeStringId = R.string.battery_info_plug_type_usb;}else if (plugType ==BatteryManager.BATTERY_PLUGGED_WIRELESS) {plugTypeStringId = R.string.battery_info_plug_type_wireless;}if (plugTypeStringId != 0){statusString = String.format("%s(%s)",statusString,res.getString(plugTypeStringId));}// show charge type by software UI，end} else if (status == BatteryManager.BATTERY_STATUS_DISCHARGING) {statusString = res.getString(R.string.battery_info_status_discharging);} else if (status == BatteryManager.BATTERY_STATUS_NOT_CHARGING) {statusString = res.getString(R.string.battery_info_status_not_charging);} else if (status == BatteryManager.BATTERY_STATUS_FULL) {statusString = res.getString(R.string.battery_info_status_full);} else {statusString = res.getString(R.string.battery_info_status_unknown);}return statusString;}

第一步：读取BatteryService.java#sendBatteryChangedIntentLocked中相应的key，默认value是未知，value已经根据在整体流程运行中分析出来了
第二步：根据status去比对当前充电状态（为充电，正在充电，断开充电连接，未知）

看到第一个if语句，再次去读取BatteryService.java#sendBatteryChangedIntentLocked中的key，判断是否是AC/USB/WLC/未知中的哪一种充电类型，在UI上显示即可。

But，往往不尽人意，底层始终读取不了AC/USB/WLC三种充电类型，搞了很久很久，才发现，我特喵的把充电类型的父目录的权限给改变了，才导致父目录下的所有节点无法读取，在init6763.rc中恢复权限即可
最后：

如果有分析不是很正确的地方还请指正，能够看完的都是人上人

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