Android中获取电池电量

/**   *    * @author chrp   *   *显示当前电池电量   */  public class MainActivity extends Activity {     private TextView tv;      /**    * 广播接受者    */   class BatteryReceiver extends BroadcastReceiver{      @Override    public void onReceive(Context context, Intent intent) {     // TODO Auto-generated method stub     //判断它是否是为电量变化的Broadcast Action     if(Intent.ACTION_BATTERY_CHANGED.equals(intent.getAction())){      //获取当前电量      int level = intent.getIntExtra("level", 0);      //电量的总刻度      int scale = intent.getIntExtra("scale", 100);      //把它转成百分比      tv.setText("电池电量为"+((level*100)/scale)+"%");     }    }       }   @Override   protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    //setContentView(R.layout.activity_main);        tv = new TextView(this);    tv.setText("chrp");    this.setContentView(tv);        //注册广播接受者java代码    IntentFilter intentFilter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);    //创建广播接受者对象    BatteryReceiver batteryReceiver = new BatteryReceiver();        //注册receiver    registerReceiver(batteryReceiver, intentFilter);   }