android低电量模式吗,Android P 省电模式(LowPowerMode)(二) ------ 省电行为
在上篇文章Android P 省电模式(LowPowerMode)(一) ------ 省电模式手动开启流程 中最后分析到，开启省电模式后，会在 BatterySaverController 中回调所有注册的 LowPowerModeListener(onLowPowerModeChanged)和 plugin(onBatterySaverChanged)，并发出广播。 我们看一下 系统做了哪些事情来实现省电。
主要有 振动，亮度，网络访问，GPS位置信息，动画，语音识别几个方面。
1. 限制振动 VibratorService.java
VibratorService.java中回调：
public void systemReady() {
Trace.traceBegin(Trace.TRACE_TAG_VIBRATOR, "VibratorService#systemReady");
try {
..........................
mPowerManagerInternal = LocalServices.getService(PowerManagerInternal.class);
mPowerManagerInternal.registerLowPowerModeObserver(
new PowerManagerInternal.LowPowerModeListener() {
@Override
public int getServiceType() {
return ServiceType.VIBRATION;
}
@Override
public void onLowPowerModeChanged(PowerSaveState result) {
updateVibrators();//更改低电量状态
}
});
..........................
}
private void updateVibrators() {
synchronized (mLock) {
boolean devicesUpdated = updateInputDeviceVibratorsLocked();
boolean lowPowerModeUpdated = updateLowPowerModeLocked();//更改低电量状态
updateVibrationIntensityLocked();
if (devicesUpdated || lowPowerModeUpdated) {
// If the state changes out from under us then just reset.
doCancelVibrateLocked();
}
}
}
private boolean updateLowPowerModeLocked() {
boolean lowPowerMode = mPowerManagerInternal
.getLowPowerState(ServiceType.VIBRATION).batterySaverEnabled;//看看这个值怎么拿到的
if (lowPowerMode != mLowPowerMode) {
mLowPowerMode = lowPowerMode;//mLowPowerMode这个变量判断要不要震动会用到
return true;
}
return false;
}
frameworks\base\services\core\java\com\android\server\power\PowerManagerService.java :
@Override
public PowerSaveState getLowPowerState(@ServiceType int serviceType) {
return mBatterySaverPolicy.getBatterySaverPolicy(serviceType,
mBatterySaverController.isEnabled());//这个方法根据传入的serviceType 决定要不要对省电模式做出反应，很关键的方法
}
frameworks\base\services\core\java\com\android\server\power\BatterySaverPolicy.java :
/**
* Get the {@link PowerSaveState} based on {@paramref type} and {@paramref realMode}.
* The result will have {@link PowerSaveState#batterySaverEnabled} and some other
* parameters when necessary.
*
* @param type type of the service, one of {@link ServiceType}
* @param realMode whether the battery saver is on by default
* @return State data that con