读取 android 设备的电池信息：

通过创建BroadcastReceiver来侦测系统中有关电池Intent(ACTION_BATTERY_CHANGED)的变化，一旦有接收到相关事件，将会读取当前电量情况，并通过TextViews显示在当前屏幕。

public class Main extends Activity {   private TextView contentTxt;   private BroadcastReceiver mBatInfoReceiver = newBroadcastReceiver(){        @Override      public void onReceive(Context arg0, Intent intent) {        // TODO Auto-generated method stub        int level = intent.getIntExtra("level", 0);        contentTxt.setText(String.valueOf(level) + "%");      }   };    @Override   public void onCreate(Bundle) {      super.onCreate(icicle);      setContentView(R.layout.main);      contentTxt = (TextView) this.findViewById(R.id.monospaceTxt);      this.registerReceiver(this.mBatInfoReceiver,         new IntentFilter(Intent.ACTION_BATTERY_CHANGED));   }}