Broadcat监视电量变化

/**
*检测手机电量变化
*     使用registerReceiver(receiver, intentFilter);来注册广播，而不是在清单文件中注册<receiver><receiver>
*     需要添加权限：
*         <uses-permission android:name="android.permission.BATTERY_STATS"/>
* 在onResume()中注册广播
*         registerReceiver(receiver, intentFilter);
* 在onPause()中注销广播
*         unregisterReceiver(receiver);
*广播接收者中检测处理电量的变化
*  检测意图 电量变化：Intent.ACTION_BATTERY_CHANGED
*
*  获取当前电量
*      int level = intent.getIntExtra("level", 0);
*  获取总电量
*      int scale = intent.getIntExtra("scale", 100);
*
*
*/
public class MainActivity extends Activity {
TextView tv;
private BroadcastReceiver receiver;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tv = (TextView)findViewById(R.id.tv);

}

@Override
protected void onResume() {
super.onResume();
receiver = new MyReceiver();
//意图过滤器， 过滤电量变化
IntentFilter intentFilter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
//注册广播接收者
registerReceiver(receiver, intentFilter);
}

@Override
protected void onPause() {
super.onPause();
//注销广播接收者
unregisterReceiver(receiver);
}

/**
* 广播接收者
*/
private class MyReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
if(intent.getAction().equals(Intent.ACTION_BATTERY_CHANGED)) {//系统的电量变化action
//当前电量 "level"
int level = intent.getIntExtra("level", 0);
//总电量
int scale = intent.getIntExtra("scale", 100);
//显示
tv.setText("当前电量"+ (level * 100) / scale + "%");
}
}
}

}