Question

我制作了一个简单的音乐播放器，可以在后台播放一些歌曲。转到主屏幕并通过通知重新打开应用程序。

我遇到的唯一问题是，如果我在音乐播放器活动中按后退按钮（转到父活动）我的应用程序崩溃了。有两个类，活动MP3Player.java和服务MP3Service.jave。

我收到以下错误：

java.lang.RuntimeException：无法销毁活动{package / package.MP3Player}：java.lang.IllegalArgumentException：服务未注册：package.MP3Player$1@b135b300

你知道有什么建议吗？提前谢谢！

EDIT1： 在我的玩家活动中，我将这样的玩家绑定在一起： MP3Player.java（活动）

playIntent = new Intent(this, MP3Service.class);
bindService(playIntent, musicConnection, Context.BIND_AUTO_CREATE);
startService(playIntent);

我使用了this教程并对其进行了修改。

编辑3： 现在我收到了这个错误：

java.lang.RuntimeException：无法停止服务包.MP3Service@b13a6f80：java.lang.IllegalStateException

MP3Service.java

public void onCreate() {
    super.onCreate();
    songPosn = 0;
    player = new MediaPlayer();
    initMusicPlayer();
}

public void initMusicPlayer() {
    player.setAudioStreamType(AudioManager.STREAM_MUSIC);
}

...

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
    return START_STICKY;
}

public void setList(ArrayList<Song> theSongs) {
    songs = theSongs;
}

public class MusicBinder extends Binder {
    MP3Service getService() {
        return MP3Service.this;
    }
}

@Override
public IBinder onBind(Intent intent) {
    return musicBind;
}

@Override
public boolean onUnbind(Intent intent) {
    player.stop();
    player.release();
    return false;
}

public void playSong() {
    player.reset();

    Song playSong = songs.get(songPosn);

    try {
        player.setDataSource(getApplicationContext(),
                Uri.parse(playSong.getPath()));
    } catch (Exception e) {
        Log.e("MUSIC SERVICE", "Error setting data source", e);
    }
    player.prepareAsync();
}

public void pauseMusic() {
    if (player.isPlaying()) {
        player.pause();
        length = player.getCurrentPosition();
    }
}

public void resumeMusic() {
    if (player.isPlaying() == false) {
        player.seekTo(this.length);
        player.start();
    } else {
        Toast.makeText(getApplicationContext(),
                "Please select a song to play", Toast.LENGTH_LONG).show();
    }
}

public void stopMusic() {
    player.stop();
    player.release();
    player = null;
}

// set the song
public void setSong(int songIndex) {
    songPosn = songIndex;

}

@Override
public void onPrepared(MediaPlayer mp) {
    mp.start();
}

@Override
public void onDestroy() {
    super.onDestroy();
    if (player != null) {
        try {
            player.stop();
            player.release();
        } finally {
            player = null;
        }
    }
}

MP3Player.java

    @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_mp3_player);
    getActionBar().setDisplayHomeAsUpEnabled(true);

    songList = getSongList();

    listAdapter = new PlayListAdapter(this, songList);
    listMusic.setAdapter(listAdapter);

    listMusic.setOnItemClickListener(new OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int pos,
                long arg3) {
            currentSongPos = pos;
            musicSrv.setSong(currentSongPos);
            musicSrv.playSong();
        }
    });

}

private ServiceConnection musicConnection = new ServiceConnection() {
    @Override
    public void onServiceConnected(ComponentName name, IBinder service) {
        MusicBinder binder = (MusicBinder) service;
        musicSrv = binder.getService();
        musicSrv.setList(songList);
        musicBound = true;
    }

    @Override
    public void onServiceDisconnected(ComponentName name) {
        musicBound = false;
    }
};

@Override
protected void onStart() {
    super.onStart();
    if (playIntent == null) {
        playIntent = new Intent(this, MP3Service.class);
        bindService(playIntent, musicConnection, Context.BIND_AUTO_CREATE);
        startService(playIntent);
    }
}


...

protected void onDestroy() {
    if (musicBound) {
        stopService(playIntent);
        unbindService(musicConnection);
        musicSrv = null;
    }
    super.onDestroy();
}

Answer 1

Service not registered表示在unbindService()来电期间无法提供服务。

了解服务生命周期：API Guide: Services

修改：

尝试添加：

protected void onDestroy() { if(musicBound){ stopService(playIntent); unbindService(musicConnection); musicSrv=null; } super.onDestroy(); }

编辑2 ：

抱歉我的错，您需要先致电stopService()，然后再致电unbindService()

stopService（）的Android文档声明：

请注意，如果已停止的服务仍然具有绑定到它的ServiceConnection对象并且设置了BIND_AUTO_CREATE，则不会销毁它直到删除所有这些绑定。请参阅服务文档有关服务生命周期的更多详细信息。

MusicPlayer在单击后退按钮时崩溃

1 个答案: