Android5.1 PowerManagerService深入分析.doc

Android5.1 PowerManagerService深入分析PowerManagerService提供Android系统的电源管理服务，主要功能是控制系统的待机状态，控制显示屏的开关和亮度调节等。PowerManagerService在systemserver中创建，加入到serviceManager中：java view plain copymPowerManagerService = mSystemServiceManager.startService(PowerManagerService.class); 先从构造函数分析，代码如下： java view plain copypublic PowerManagerService(Context context) super(context); mContext = context; /创建处理消息的线程 mHandlerThread = new ServiceThread(TAG, Process.THREAD_PRIORITY_DISPLAY, false /*allowIo*/); mHandlerThread.start(); /创建Handler，注意mHandlerThread.getLooper()，每一个线程都只有一个looper，这样消息的处理会放在这个线程中 mHandler = new PowerManagerHandler(mHandlerThread.getLooper(); synchronized (mLock) mWakeLockSuspendBlocker = createSuspendBlockerLocked(PowerManagerService.WakeLocks); mDisplaySuspendBlocker = createSuspendBlockerLocked(PowerManagerService.Display); /防止cpu进入睡眠状态 mDisplaySuspendBlocker.acquire(); mHoldingDisplaySuspendBlocker = true; mHalAutoSuspendModeEnabled = false; mHalInteractiveModeEnabled = true; /当前系统状态正常运行状态 mWakefulness = WAKEFULNESS_AWAKE; nativeInit(); nativeSetAutoSuspend(false); nativeSetInteractive(true); 构造函数比较简单，创建了一个接受消息处理的线程，cpu持锁不让手机睡眠，以及一些变量的初始化。SystemServer创建完PowerManagerService后，继续调用SystemReady方法，再做一些初始化的工作，代码如下：java view plain copypublic void systemReady(IAppOpsService appOps) synchronized (mLock) mSystemReady = true; mAppOps = appOps; /android5.0后的新方法，localService可以直接取，在4.4中这样service是在init中传对象进来的 mDreamManager = getLocalService(DreamManagerInternal.class); mDisplayManagerInternal = getLocalService(DisplayManagerInternal.class); mPolicy = getLocalService(WindowManagerPolicy.class); mBatteryManagerInternal = getLocalService(BatteryManagerInternal.class); PowerManager pm = (PowerManager) mContext.getSystemService(Context.POWER_SERVICE); /获取缺省、最大、最小屏幕亮度 mScreenBrightnessSettingMinimum = pm.getMinimumScreenBrightnessSetting(); mScreenBrightnessSettingMaximum = pm.getMaximumScreenBrightnessSetting(); mScreenBrightnessSettingDefault = pm.getDefaultScreenBrightnessSetting(); /创建sensorManager和sersorservice交互 SensorManager sensorManager = new SystemSensorManager(mContext, mHandler.getLooper(); / The notifier runs on the system servers main looper so as not to interfere / with the animations and other critical functions of the power manager. mBatteryStats = BatteryStatsService.getService(); mNotifier = new Notifier(Looper.getMainLooper(), mContext, mBatteryStats, mAppOps, createSuspendBlockerLocked(PowerManagerService.Broadcasts), mPolicy); /创建检测无线充电的对象 mWirelessChargerDetector = new WirelessChargerDetector(sensorManager, createSuspendBlockerLocked(PowerManagerService.WirelessChargerDetector), mHandler); mSettingsObserver = new SettingsObserver(mHandler); mLightsManager = getLocalService(LightsManager.class); mAttentionLight = mLightsManager.getLight(LightsManager.LIGHT_ID_ATTENTION); / Initialize display power management. mDisplayManagerInternal.initPowerManagement( mDisplayPowerCallbacks, mHandler, sensorManager); / Register for broadcasts from other components of the system. /监听其他模块的广播 IntentFilter filter = new IntentFilter(); filter.addAction(Intent.ACTION_BATTERY_CHANGED); filter.setPriority(IntentFilter.SYSTEM_HIGH_PRIORITY); mContext.registerReceiver(new BatteryReceiver(), filter, null, mHandler); filter = new IntentFilter(); filter.addAction(Intent.ACTION_DREAMING_STARTED); filter.addAction(Intent.ACTION_DREAMING_STOPPED); mContext.registerReceiver(new DreamReceiver(), filter, null, mHandler); filter = new IntentFilter(); filter.addAction(Intent.ACTION_USER_SWITCHED); mContext.registerReceiver(new UserSwitchedReceiver(), filter, null, mHandler); filter = new IntentFilter(); filter.addAction(Intent.ACTION_DOCK_EVENT); mContext.registerReceiver(new DockReceiver(), filter, null, mHandler); / Register for settings changes. final ContentResolver resolver = mContext.getContentResolver(); resolver.registerContentObserver(Settings.Secure.getUriFor( Settings.Secure.SCREENSAVER_ENABLED), false, mSettingsObserver, UserHandle.USER_ALL); resolver.registerContentObserver(Settings.Secure.getUriFor( Settings.Secure.SCREENSAVER_ACTIVATE_ON_SLEEP), false, mSettingsObserver, UserHandle.USER_ALL); resolver.registerContentObserver(Settings.Secure.getUriFor( Settings.Secure.SCREENSAVER_ACTIVATE_ON_DOCK), false, mSettingsObserver, UserHandle.USER_ALL); resolver.registerContentObserver(Settings.System.getUriFor( Settings.System.SCREEN_OFF_TIMEOUT), false, mSettingsObserver, UserHandle.USER_ALL); resolver.registerContentObserver(Settings.Secure.getUriFor( Settings.Secure.SLEEP_TIMEOUT), false, mSettingsObserver, UserHandle.USER_ALL); resolver.registerContentObserver(Settings.Global.getUriFor( Settings.Global.STAY_ON_WHILE_PLUGGED_IN), false, mSettingsObserver, UserHandle.USER_ALL); resolver.registerContentObserver(Settings.System.getUriFor( Settings.System.SCREEN_BRIGHTNESS), false, mSettingsObserver, UserHandle.USER_ALL); resolver.registerContentObserver(Settings.System.getUriFor( Settings.System.SCREEN_BRIGHTNESS_MODE), false, mSettingsObserver, UserHandle.USER_ALL); resolver.registerContentObserver(Settings.System.getUriFor( Settings.System.SCREEN_AUTO_BRIGHTNESS_ADJ), false, mSettingsObserver, UserHandle.USER_ALL); resolver.registerContentObserver(Settings.Global.getUriFor( Settings.Global.LOW_POWER_MODE), false, mSettingsObserver, UserHandle.USER_ALL); resolver.registerContentObserver(Settings.Global.getUriFor( Settings.Global.LOW_POWER_MODE_TRIGGER_LEVEL), false, mSettingsObserver, UserHandle.USER_ALL); resolver.registerContentObserver(Settings.Global.getUriFor( Settings.Global.THEATER_MODE_ON), false, mSettingsObserver, UserHandle.USER_ALL); / Go. readConfigurationLocked(); updateSettingsLocked(); mDirty |= DIRTY_BATTERY_STATE; updatePowerStateLocked(); 从在android5.1.1中，service一般都会继承一个虚类SystemService，在其中定义了两个接口onStart和onBootPhase，分别是PowerManagerService启动的时候会调用，而onBootPhase会在系统启动的各个阶段来调用，下面我们分别来看看在powerManagerService中这两个函数的实现：java view plain copyOverride public void onStart() publishBinderService(Context.POWER_SERVICE, new BinderService(); publishLocalService(PowerManagerInternal.class, new LocalService(); Watchdog.getInstance().addMonitor(this); Watchdog.getInstance().addThread(mHandler); 在onstart函数中，必须把一些接口publish，像在之前Binder的接口，都是通过PowerManagerService extends IPowerManager.Stub形式在PowerManagerService中实现接口而在android5.1.1中都是通过方式重新定义一个类，然后把这个类publish出去。java view plain copyprivate final class BinderService extends IPowerManager.Stub Override / Binder call public void acquireWakeLockWithUid(IBinder lock, int flags, String tag, String packageName, int uid) if (uid = 0) 查找到 wakeLock = mWakeLocks.get(index); if (!wakeLock.hasSameProperties(flags, tag, ws, uid, pid) 属性不一样，更新 / Update existing wake lock. This shouldnt happen but is harmless. notifyWakeLockChangingLocked(wakeLock, flags, tag, packageName, uid, pid, ws, historyTag); wakeLock.updateProperties(flags, tag, packageName, ws, historyTag, uid, pid); notifyAcquire = false; else 没找到，重新建立，添加 wakeLock = new WakeLock(lock, flags, tag, packageName, ws, historyTag, uid, pid); try lock.linkToDeath(wakeLock, 0); catch (RemoteException ex) throw new IllegalArgumentException(Wake lock is already dead.); mWakeLocks.add(wakeLock); notifyAcquire = true; /看是否需要点亮屏幕 applyWakeLock