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。

 

/** Copyright (C) 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;/*** <p>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.</p>* <p>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:</p>* <p>"scale" - int, the maximum value for the charge level</p>* <p>"level" - int, charge level, from 0 through "scale" inclusive</p>* <p>"status" - String, the current charging status.<br />* <p>"health" - String, the current battery health.<br />* <p>"present" - boolean, true if the battery is present<br />* <p>"icon-small" - int, suggested small icon to use for this state</p>* <p>"plugged" - int, 0 if the device is not plugged in; 1 if plugged* into an AC power adapter; 2 if plugged in via USB.</p>* <p>"voltage" - int, current battery voltage in millivolts</p>* <p>"temperature" - int, current battery temperature in tenths of* a degree Centigrade</p>* <p>"technology" - String, the type of battery installed, e.g. "Li-ion"</p>** <p>* 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.* </p>*/
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 criticalprivate 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;
//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_OKAYmLowBatteryCloseWarningLevel = 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 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 {
//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() {@Overridepublic void run() {if (ActivityManagerNative.isSystemReady()) {Intent intent = new Intent("android.intent.action.ACTION_REQUEST_SHUTDOWN_LOWBATTERY");//ACTION_REQUEST_SHUTDOWNintent.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() {@Overridepublic void run() {if (ActivityManagerNative.isSystemReady()) {Intent intent = new Intent("android.intent.action.ACTION_REQUEST_SHUTDOWN_LOWBATTERY");//ACTION_REQUEST_SHUTDOWNintent.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 againmDischargeStartTime = 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 upmDischargeStartTime = 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 15sendIntentLocked();//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);}});}
//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() {@Overridepublic 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() {@Overridepublic 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 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;}}
//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 everyonefinal 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() {@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;}}@Overrideprotected 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

/** Copyright (C) 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_CHANGEDstatic 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）：

         <activity android:name="com.android.server.ShutdownLowBatteryActivity"android:theme="@android:style/Theme.Translucent.NoTitleBar"android:configChanges="orientation|keyboardHidden|screenSize"android:windowSoftInputMode="stateHidden"android:permission="android.permission.SHUTDOWN"android:excludeFromRecents="true"><intent-filter><action android:name="android.intent.action.ACTION_REQUEST_SHUTDOWN_LOWBATTERY" /><category android:name="android.intent.category.DEFAULT" /></intent-filter></activity>

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：

/** Copyright (C) 2009 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.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@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;@Overrideprotected 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：

/** Copyright (C) 2013 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;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 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();@Overridepublic 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);}}@Overridepublic 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;}@Overrideprotected 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;}@Overridepublic 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();@Overridepublic 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。