电量优化

文章来源：http://wuxiaolong.me/2017/04/27/AndroidBattery/
我们可以获取当前充电状态、监控充电状态变化、监控电池电量变化

获取当前充电状态

IntentFilter ifilter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
Intent batteryStatus = context.registerReceiver(null, ifilter);

简单地调用 registerReceiver 传入 null 作为接收器来注册 BroadcastReceiver，便可返回当前电池状态 Intent。

// 充电状态
int status = batteryStatus.getIntExtra(BatteryManager.EXTRA_STATUS, -1);
boolean isCharging = status == BatteryManager.BATTERY_STATUS_CHARGING ||
        status == BatteryManager.BATTERY_STATUS_FULL;
Log.d("wxl", "isCharging=" + isCharging);
Toast.makeText(this,"isCharging=" + isCharging,Toast.LENGTH_LONG).show();
// 设备是通过 USB 还是交流充电器进行充电
int chargePlug = batteryStatus.getIntExtra(BatteryManager.EXTRA_PLUGGED, -1);
boolean usbCharge = chargePlug == BatteryManager.BATTERY_PLUGGED_USB;
boolean acCharge = chargePlug == BatteryManager.BATTERY_PLUGGED_AC;
Log.d("wxl", "usbCharge=" + usbCharge + ",acCharge=" + acCharge);
Toast.makeText(this,"usbCharge=" + usbCharge + ",acCharge=" + acCharge,Toast.LENGTH_LONG).show();

监控充电状态变化

清单文件中注册一个 BroadcastReceiver，通过在一个 Intent 过滤器内定义 ACTION_POWER_CONNECTED 和 ACTION_POWER_DISCONNECTED 来同时侦听这两种事件

<receiver android:name=".PowerConnectionReceiver">
  <intent-filter>
    <action android:name="android.intent.action.ACTION_POWER_CONNECTED"/>
    <action android:name="android.intent.action.ACTION_POWER_DISCONNECTED"/>
  </intent-filter>
</receiver>

PowerConnectionReceiver

public class PowerConnectionReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        int status = intent.getIntExtra(BatteryManager.EXTRA_STATUS, BatteryManager.BATTERY_STATUS_UNKNOWN);
        String batteryStatus = "";
        switch (status) {
            case BatteryManager.BATTERY_STATUS_CHARGING:
                batteryStatus = "正在充电";
                break;
            case BatteryManager.BATTERY_STATUS_DISCHARGING:
                batteryStatus = "正在放电";
                break;
            case BatteryManager.BATTERY_STATUS_NOT_CHARGING:
                batteryStatus = "未充电";
                break;
            case BatteryManager.BATTERY_STATUS_FULL:
                batteryStatus = "充满电";
                break;
            case BatteryManager.BATTERY_STATUS_UNKNOWN:
                batteryStatus = "未知道状态";
                break;
        }
        Toast.makeText(context, "batteryStatus=" + batteryStatus, Toast.LENGTH_LONG).show();
        int plugged = intent.getIntExtra(BatteryManager.EXTRA_PLUGGED, BatteryManager.BATTERY_PLUGGED_AC);
        String chargePlug = "";
        switch (plugged) {
            case BatteryManager.BATTERY_PLUGGED_AC:
                chargePlug = "AC充电";
                break;
            case BatteryManager.BATTERY_PLUGGED_USB:
                chargePlug = "USB充电";
                break;
            case BatteryManager.BATTERY_PLUGGED_WIRELESS:
                chargePlug = "无线充电";
                break;
        }
        Toast.makeText(context, "chargePlug=" + chargePlug, Toast.LENGTH_LONG).show();
    }
}

注册

IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction(Intent.ACTION_BATTERY_CHANGED);
this.registerReceiver(new PowerConnectionReceiver(), intentFilter);

监控电池电量变化

清单文件中注册一个 BroadcastReceiver，通过侦听 ACTION_BATTERY_LOW 和 ACTION_BATTERY_OKAY，每当设备电池电量不足或退出不足状态时，便会触发该接收器。

<receiver android:name=".BatteryLevelReceiver">
<intent-filter>
  <action android:name="android.intent.action.ACTION_BATTERY_LOW"/>
  <action android:name="android.intent.action.ACTION_BATTERY_OKAY"/>
  </intent-filter>
</receiver>

BatteryLevelReceiver

public class BatteryLevelReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        //当前剩余电量
        int level = intent.getIntExtra(BatteryManager.EXTRA_LEVEL, -1);
        //电量最大值
        int scale = intent.getIntExtra(BatteryManager.EXTRA_SCALE, -1);
        //电量百分比
        float batteryPct = level / (float) scale;
        Log.d("wxl", "batteryPct=" + batteryPct);
        Toast.makeText(context, "batteryPct=" + batteryPct, Toast.LENGTH_LONG).show();
    }
}

注册

IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction(Intent.ACTION_BATTERY_CHANGED);
this.registerReceiver(new BatteryLevelReceiver(), intentFilter);

通常，如果设备连接了交流充电器，您应该最大限度提高后台更新的频率；而如果设备是通过 USB 充电，则应降低更新频率，如果电池正在放电，则应进一步降低更新频率；在电池电量极低时停用所有后台更新。