Android电源管理系统调研报告-（3）

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一、powermanagerservice.java1、nest class

1)、private class UnsynchronizedWakeLock

从类名可以看出这个类实现的是异步获取唤醒锁。当PowerManager.WakeLock与 synchronizing on mLocks之间发生死锁的时候，这个类可以重新实现PowerManager.WakeLock。由于它没有外部同步块，所以只有当拥有锁的时候才调用这个类。

该类实现的方法有：

public void acquire()

public void release()

public boolean isHeld()

public String toString()

构造方法：

UnsynchronizedWakeLock(int flags, String tag, boolean refCounted)

2）、private final class BatteryReceiver extends BroadcastReceiver

这个类是个广播接收，至于广播的使用，这里不作深入的探讨。该类重载了接收的方法。当然，接收的过程是有约束的，即同步mLocks。

@Override

public void onReceive(Context context, Intent intent)

synchronized (mLocks)

即使当keyguard is on

synchronized (mLocks) {

forceUserActivityLocked();

3）、private final class BootCompletedReceiver extends BroadcastReceiver

@Override

public void onReceive(Context context, Intent intent) {

bootCompleted();

}

该广播能接收到启动完成后的消息，而后调用bootCompleted()。

4）、private final class DockReceiver extends BroadcastReceiver

5）、private class SettingsObserver implements Observer

6）、private class WakeLock implements IBinder.DeathRecipient

方法public void binderDied()会调用releaseWakeLockLocked

synchronized (mLocks) {

releaseWakeLockLocked(this.binder, 0, true);

7）、private class PokeLock implements IBinder.DeathRecipient

方法public void binderDied() 调用

setPokeLock(0,this.binder, this.tag);

8）、private class TimeoutTask implements Runnable

该类实现了Runnable接口，有一个run方法。

run方法实现的是Timeout后进行的动作，setTimeoutLocked(now,SCREEN_DIM);？setTimeoutLocked(now,SCREEN_OFF);

9）、class BrightnessState

该类定义的方法有

BrightnessState(int m)

public void dump(PrintWriter pw, String prefix)

boolean setTargetLocked(int target, int stepsToTarget, int initialValue,int nominalCurrentValue)

delta = (targetValue -(nominalCurrentValue >= 0 ?nominalCurrentValue : curValue))/ stepsToTarget;

boolean stepLocked()

10）、private class LightAnimator implements Runnable

该类实现了Runnable接口，有一个run方法

run方法实现的是亮度变化的控制：

ScreenBrightness

KeyboardBrightness

ButtonBrightness

这三个设备亮度分步控制。

if (mKeyboardBrightness.stepLocked()) {

more = true;

}

if (mButtonBrightness.stepLocked()) {

more = true;

}

if (more) {

mHandler.postAtTime(mLightAnimator, now+(1000/60));

11）、private class GservicesChangedReceiver extends BroadcastReceiver

该类继承了广播接口的类，方法onReceive调用了updateGservicesValues()。

该类当接收到google service改变的广播时，就受调用updateGservicesValues()。

12）、private class LockList extends ArrayList<WakeLock>

方法：

void addLock(WakeLock wl)

WakeLock removeLock(IBinder binder)

int getIndex(IBinder binder)

int gatherState()

int reactivateScreenLocksLocked()

该类实践上是建立了一了锁队列/锁列表，该队列可以通过addLock新建一个锁，也可以通过removeLock从队列中摘除一个锁，可以通过getIndex查询指定锁在队列中的索引号

定义了一个该类的实例

private final LockList mLocks = new LockList();

整个service中方法的调用都同步这个对象mLocks

synchronized (mLocks)

2、相关的service：BatteryService

mBatteryService.isPowered()

mBatteryService.getBatteryLevel()

BatteryStatsService.getService()

GservicesHardwareserviceActivityService

3、参数

//flags for setPowerState

private static final intSCREEN_ON_BIT = 0x00000001;

private static final intSCREEN_BRIGHT_BIT = 0x00000002;

private static final intBUTTON_BRIGHT_BIT = 0x00000004;

private static final intKEYBOARD_BRIGHT_BIT = 0x00000008;

private static final intBATTERY_LOW_BIT = 0x00000010;

//SCREEN_OFF == everything off

private static final intSCREEN_OFF = 0x00000000;

//SCREEN_DIM == screen on, screen backlight dim

private static final intSCREEN_DIM = SCREEN_ON_BIT;

//SCREEN_BRIGHT == screen on, screen backlight bright

private static final intSCREEN_BRIGHT = SCREEN_ON_BIT |SCREEN_BRIGHT_BIT;

//SCREEN_BUTTON_BRIGHT == screen on, screen and button backlights bright

private static final intSCREEN_BUTTON_BRIGHT = SCREEN_BRIGHT |BUTTON_BRIGHT_BIT;

//SCREEN_BUTTON_BRIGHT == screen on, screen, button and keyboard backlightsbright

private static final intALL_BRIGHT = SCREEN_BUTTON_BRIGHT| KEYBOARD_BRIGHT_BIT;

4、提供的相关服务

提供的这些服务之间并不是独立的，而是相互交织在一起，共同完成电源管理的：

1）、光感传感器

LIGHT_SENSOR

定义了光感传感器变化明暗变化的延时：

// How long to wait to debounce light sensor changes.

private static final int LIGHT_SENSOR_DELAY = 2000;