BroadcastReceiver：按下电源按钮时打开/关闭

Question

我使用BroadcastReceiver类通过声音发出了一个简单的警报，我希望在用户按下电源按钮时关闭声音。

我尝试了下面的代码，但是当按下电源按钮时声音没有关闭：

public class MyBroadcastReceiver extends BroadcastReceiver {
    MediaPlayer mp;
    @Override
    public void onReceive(Context context, Intent intent) {
        mp = MediaPlayer.create(context, R.raw.sound);
        KeyguardManager myKM = (KeyguardManager) 
        context.getSystemService(Context.KEYGUARD_SERVICE);
        if (myKM.inKeyguardRestrictedInputMode()) {
            //it is locked
            mp.stop();
        } else {
            //it is not locked
            mp.start();
            Toast.makeText(context, "Alarm starting....", Toast.LENGTH_LONG).show();
        }
    }
}

我可以为上述问题找到最佳解决方案吗？