Android 从锁屏中醒来后应用程序崩溃

我的应用程序是某种闹钟。我希望它能够从锁屏中醒来，进入报警活动。 活动：

import java.io.IOException;

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.media.RingtoneManager;
import android.net.Uri;
import android.os.Bundle;
import android.os.PowerManager;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.TextView;


public class AlarmReceiverActivity extends Activity {
    private MediaPlayer mMediaPlayer; 
    private PowerManager.WakeLock wl;
    String titl;
    private static boolean active=false;

    public static boolean isActive() {
        return active;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        active=true;
        PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
        wl = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "My Tag");
        wl.acquire();
        Log.d("alarm", "got here");
        this.requestWindowFeature(Window.FEATURE_NO_TITLE);
        this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN | 
                WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD | 
                WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED | 
                WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON,
                WindowManager.LayoutParams.FLAG_FULLSCREEN | 
                WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD | 
                WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED | 
                WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON);
        setContentView(R.layout.alarm);
        TextView text = (TextView)findViewById(R.id.tvt);
        Intent inte1 = getIntent();
        text.setText(inte1.getExtras().getCharSequence("titl"));
        Button stopAlarm = (Button) findViewById(R.id.stopAlarm);
        stopAlarm.setOnTouchListener(new OnTouchListener() {
            public boolean onTouch(View arg0, MotionEvent arg1) {
                mMediaPlayer.stop();
                Intent ss = new Intent(AlarmReceiverActivity.this,BackgroundLocationService.class);
                stopService(ss);
                Intent i =new Intent(AlarmReceiverActivity.this,MnaActivity.class);
                startActivity(i);
                return false;
            }
        });

        playSound(this, getAlarmUri());
    }

    @Override
    protected void onStop() {
        super.onStop();
        active=false;
        wl.release();
    }

    private void playSound(Context context, Uri alert) {
        mMediaPlayer = new MediaPlayer();
        try {
            mMediaPlayer.setDataSource(context, alert);
            final AudioManager audioManager = (AudioManager) context
                    .getSystemService(Context.AUDIO_SERVICE);
            if (audioManager.getStreamVolume(AudioManager.STREAM_ALARM) != 0) {
                mMediaPlayer.setAudioStreamType(AudioManager.STREAM_ALARM);
                mMediaPlayer.prepare();
                mMediaPlayer.start();
            }
        } catch (IOException e) {
            System.out.println("OOPS");
        }
    }
    @Override
    public void onBackPressed()
    {
        mMediaPlayer.stop();
        Intent ss = new Intent(AlarmReceiverActivity.this,BackgroundLocationService.class);
        stopService(ss);
        Intent i =new Intent(AlarmReceiverActivity.this,MnaActivity.class);
        startActivity(i);
    }
    //Get an alarm sound. Try for an alarm. If none set, try notification, 
    //Otherwise, ringtone.
    private Uri getAlarmUri() {
        Uri alert = RingtoneManager
                .getDefaultUri(RingtoneManager.TYPE_ALARM);
        if (alert == null) {
            alert = RingtoneManager
                    .getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
            if (alert == null) {
                alert = RingtoneManager
                        .getDefaultUri(RingtoneManager.TYPE_RINGTONE);
            }
        }
        return alert;
    }
} 

当我从锁屏测试它时，它工作正常，直到我点击stopAlarm按钮，然后它崩溃。但是，当此活动没有从锁屏打开时，它会按照预期的方式工作。我在logcat中得到这个错误：

06-03 10:14:09.921: E/AndroidRuntime(2411): FATAL EXCEPTION: main
06-03 10:14:09.921: E/AndroidRuntime(2411): Process: com.example.fgps, PID: 2411
06-03 10:14:09.921: E/AndroidRuntime(2411): java.lang.RuntimeException: Unable to stop activity {com.example.fgps/com.example.fgps.AlarmReceiverActivity}: java.lang.RuntimeException: WakeLock under-locked My Tag
06-03 10:14:09.921: E/AndroidRuntime(2411):     at android.app.ActivityThread.performStopActivityInner(ActivityThread.java:3188)
06-03 10:14:09.921: E/AndroidRuntime(2411):     at android.app.ActivityThread.handleStopActivity(ActivityThread.java:3234)
06-03 10:14:09.921: E/AndroidRuntime(2411):     at android.app.ActivityThread.access$1100(ActivityThread.java:135)
06-03 10:14:09.921: E/AndroidRuntime(2411):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1223)
06-03 10:14:09.921: E/AndroidRuntime(2411):     at android.os.Handler.dispatchMessage(Handler.java:102)
06-03 10:14:09.921: E/AndroidRuntime(2411):     at android.os.Looper.loop(Looper.java:136)
06-03 10:14:09.921: E/AndroidRuntime(2411):     at android.app.ActivityThread.main(ActivityThread.java:5017)
06-03 10:14:09.921: E/AndroidRuntime(2411):     at java.lang.reflect.Method.invokeNative(Native Method)
06-03 10:14:09.921: E/AndroidRuntime(2411):     at java.lang.reflect.Method.invoke(Method.java:515)
06-03 10:14:09.921: E/AndroidRuntime(2411):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
06-03 10:14:09.921: E/AndroidRuntime(2411):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
06-03 10:14:09.921: E/AndroidRuntime(2411):     at dalvik.system.NativeStart.main(Native Method)
06-03 10:14:09.921: E/AndroidRuntime(2411): Caused by: java.lang.RuntimeException: WakeLock under-locked My Tag
06-03 10:14:09.921: E/AndroidRuntime(2411):     at android.os.PowerManager$WakeLock.release(PowerManager.java:764)
06-03 10:14:09.921: E/AndroidRuntime(2411):     at android.os.PowerManager$WakeLock.release(PowerManager.java:735)
06-03 10:14:09.921: E/AndroidRuntime(2411):     at com.example.fgps.AlarmReceiverActivity.onStop(AlarmReceiverActivity.java:74)
06-03 10:14:09.921: E/AndroidRuntime(2411):     at android.app.Instrumentation.callActivityOnStop(Instrumentation.java:1212)
06-03 10:14:09.921: E/AndroidRuntime(2411):     at android.app.Activity.performStop(Activity.java:5376)
06-03 10:14:09.921: E/AndroidRuntime(2411):     at android.app.ActivityThread.performStopActivityInner(ActivityThread.java:3185)
06-03 10:14:09.921: E/AndroidRuntime(2411):     ... 11 more

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我如何解决它？

From，在释放它之前尝试检查

wl

是否被保持。@diatrevolo它解决了问题，谢谢。From，在释放它之前尝试检查

wl

是否被保持。@diatrevolo它解决了问题，谢谢。From，在释放它之前尝试检查

wl

是否被保持。@diatrevolo它解决了问题，非常感谢。