Android5.1 电池充电剩余时间计算
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Android5.1 电池充电剩余时间计算android5.1手机在充电的时候，并且在锁屏界面的时候会显示还剩多少时间电池充满电。我们就这个机制进行下深入分析：
首先对电池的变化都会监听BatteryService发出的Intent.ACTION_BATTERY_CHANGED广播，因此在framework目录下全局搜索，结果发现在./base/packages/Keyguard/src/com/Android/keyguard/KeyguardUpdateMonitor.Java这个目录下，也就是keyguard中有对这个广播的监控
在KeyguardUpdateMonitor.java这个文件中
[java] view plain copy
private final BroadcastReceiver mBroadcastReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
final String action = intent.getAction();
if (DEBUG) Log.d(TAG, "received broadcast " + action);
if (Intent.ACTION_TIME_TICK.equals(action)
|| Intent.ACTION_TIME_CHANGED.equals(action)
|| Intent.ACTION_TIMEZONE_CHANGED.equals(action)) {
mHandler.sendEmptyMessage(MSG_TIME_UPDA TE);
} else if (Intent.ACTION_BA TTERY_CHANGED.equals(action)) {//监听电池变化的广播
final int status = intent.getIntExtra(EXTRA_STA TUS, BA TTERY_STATUS_UNKNOWN);
final int plugged = intent.getIntExtra(EXTRA_PLUGGED, 0);
final int level = intent.getIntExtra(EXTRA_LEVEL, 0);
final int health = intent.getIntExtra(EXTRA_HEALTH, BA TTERY_HEALTH_UNKNOWN);
final Message msg = mHandler.obtainMessage(
MSG_BA TTERY_UPDATE, new BatteryStatus(status, level, plugged, health));
mHandler.sendMessage(msg);//发消息
}
接下来我们搜索下MSG_BATTERY_UPDATE这个消息，
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private void handleBatteryUpdate(BatteryStatus status) {
if (DEBUG) Log.d(TAG, "handleBatteryUpdate");
final boolean batteryUpdateInteresting = isBatteryUpdateInteresting(mBatteryStatus, status);
mBatteryStatus = status;
if (batteryUpdateInteresting) {
for (int i = 0; i < mCallbacks.size(); i++) {
KeyguardUpdateMonitorCallback cb = mCallbacks.get(i).get();
if (cb != null) {
cb.onRefreshBatteryInfo(status);//接下来我们就搜一下谁定义了onRefreshBatteryInfo这个接口
}
}
}
}
结果在KeyguardIndicationController.java这个文件中
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KeyguardUpdateMonitorCallback mUpdateMonitor = new KeyguardUpdateMonitorCallback() { @Override
public void onRefreshBatteryInfo(KeyguardUpdateMonitor.BatteryStatus status) { boolean isChargingOrFull = status.status == BatteryManager.BATTERY_STA TUS_CHARGING
|| status.status == BatteryManager.BA TTERY_STATUS_FULL;
mPowerPluggedIn = status.isPluggedIn() && isChargingOrFull;
mPowerCharged = status.isCharged();
updateIndication();
}
};
接下来看下updateIndication
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private void updateIndication() {
if (mVisible) {
mTextView.switchIndication(computeIndication());
}
}
接下来就是看下如何计算电池剩余时间的
[java] view plain copy
private String computeIndication() {
if (!TextUtils.isEmpty(mTransientIndication)) {
return mTransientIndication;
}
if (mPowerPluggedIn) {//当在充电时
return computePowerIndication();
}
return mRestingIndication;
}
private String computePowerIndication() {
if (mPowerCharged) {
return mContext.getResources().getString(R.string.keyguard_charged);
}
// Try fetching charging time from battery stats.