AndroId 媒体播放器错误 (1，-4) 准备异步方法

Question

我在 prepareAsync 方法中有一个错误 （1，-4）。文档指定这是"文件格式不正确"（对吗？），但该文件是mp3格式。此外，当在另一个活动中调用媒体播放器时，在旧版本的软件中复制了相同的文件。我不知道如何解决问题，所以我在这里。

该应用程序的代码如下所示：

SingletonMediaPlayer 将管理在应用程序中用作单例的媒体播放器对象

public class SingletonMediaPlayer {
    private static SingletonMediaPlayer instance;
    private MediaPlayer mp;
    private int buffer_state;
    private SingletonMediaPlayer() {
        Log.d("SMP","Creating new media player");
        this.mp = new MediaPlayer();
        this.buffer_state = 0;
    }
    public static SingletonMediaPlayer getInstance() {
        if (instance == null) {
            instance = new SingletonMediaPlayer();
        }
        return instance; 
    }
    public void play(String path, final TextView tv_messaging){             
        if(this.mp.isPlaying()){
            Log.d("SMP","Player is playing, now I'll stop and reset it");
            this.mp.stop();
            this.mp.reset();
            this.mp.release();
        }
        Log.d("SMP","Set audio stream type");
        this.mp.setAudioStreamType(AudioManager.STREAM_MUSIC);
        try {
            Log.d("SMP","Set data source");
            this.mp.setDataSource(path);
            Log.d("SMP","Prepare async");
            this.mp.prepareAsync();
            Log.d("SMP","Done!");
            tv_messaging.setText("Connecting to the server...please wait");
        } catch (IllegalArgumentException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            tv_messaging.setText(e.toString());
            Log.e("SMP","IllegalArgumentException");
        } catch (SecurityException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            tv_messaging.setText(e.toString());
            Log.e("SMP","SecurityException");
        } catch (IllegalStateException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            tv_messaging.setText(e.toString());
            Log.e("SMP","IllegalStateException");
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            tv_messaging.setText(e.toString());
            Log.e("SMP","IOException");
        }catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            tv_messaging.setText(e.toString());
            Log.e("SMP","Generic Exception");
        }
    }
    public void checkBufferState(final TextView tv_buffer_message){
        final SingletonMediaPlayer self = this;
        Log.d("SMP","  Set on prepared listener");
        this.mp.setOnErrorListener(new OnErrorListener(){
            @Override
            public boolean onError(MediaPlayer mp, int arg1, int arg2) {
                // TODO Auto-generated method stub
                return false;
            }
        });
        this.mp.setOnPreparedListener(new OnPreparedListener() {
            public void onPrepared(MediaPlayer mPlayer) {
                OnBufferingUpdateListener lis = new OnBufferingUpdateListener(){
                    public void onBufferingUpdate(MediaPlayer mPlayer, int percent) {
                        Log.d("SMP","      Mediaplayer ready (preparation done). Inside buffer listener");
                        self.buffer_state = percent;
                        if(tv_buffer_message != null){
                            tv_buffer_message.setText(percent+"%");
                        }
                    }
                };
                Log.d("SMP","    Mediaplayer ready (preparation done). Installing buffer listener");
                mPlayer.setOnBufferingUpdateListener(lis);
                Log.d("SMP","    Mediaplayer ready (preparation done). Starting reproduction");
                mPlayer.start();
                Log.d("SMP","    Mediaplayer ready (preparation done). Done!");
            }
        });
    }
    public int getBufferState(){
        return this.buffer_state;
    }
}

我正在动态创建按钮，单击按钮时应该播放mp3。所以，就在用于创建按钮的循环之前，我有

final SingletonMediaPlayer mediaPlayer = SingletonMediaPlayer.getInstance();
mediaPlayer.checkBufferState(tv_sel_ep);

而且，对于每个按钮，我都有

button.setOnClickListener(new View.OnClickListener() {
    public void onClick(View v) {
        mediaPlayer.play(link, Text_view_used_to_show_error);
    }
});

日志

02-15 14:35:24.165: D/dalvikvm(1415): GC_EXTERNAL_ALLOC freed 58K, 52% free 2633K/5379K, external 391K/517K, paused 87ms
02-15 14:35:25.705: D/NetworkActivity(1415): Starting SelectEpisodeActivity
02-15 14:35:25.995: D/SMP(1415): Creating new media player
02-15 14:35:26.005: D/SMP(1415):   Set on prepared listener
02-15 14:35:28.745: W/KeyCharacterMap(1415): No keyboard for id 0
02-15 14:35:28.745: W/KeyCharacterMap(1415): Using default keymap: /system/usr/keychars/qwerty.kcm.bin
02-15 14:35:28.745: I/qqqqqqqqqqqqq(1415): qqqqqqqqqqqqqqqqqqqq
02-15 14:35:29.235: D/dalvikvm(1415): GC_CONCURRENT freed 307K, 53% free 2669K/5639K, external 477K/989K, paused 8ms+12ms
02-15 14:35:30.275: D/NetworkActivity(1415): Starting SelectEpisodeActivity
02-15 14:35:30.415: D/SMP(1415):   Set on prepared listener
02-15 14:35:32.485: D/SMP(1415): Set audio stream type
02-15 14:35:32.485: D/SMP(1415): Set data source
02-15 14:35:32.785: D/SMP(1415): Prepare async
02-15 14:35:32.785: D/SMP(1415): Done!
02-15 14:35:32.885: W/MediaPlayer(1415): info/warning (1, 26)
02-15 14:35:32.885: I/MediaPlayer(1415): Info (1,26)
02-15 14:35:32.885: E/MediaPlayer(1415): error (1, -4)
02-15 14:35:32.885: E/MediaPlayer(1415): Error (1,-4)

编辑：戴夫回答后的新日志

02-16 14:35:11.265: D/dalvikvm(12723): GC_EXTERNAL_ALLOC freed 59K, 52% free 2633K/5379K, external 391K/517K, paused 133ms
02-16 14:35:13.265: D/NetworkActivity(12723): Starting SelectEpisodeActivity
02-16 14:35:13.405: D/SMP(12723): Creating new media player
02-16 14:35:13.415: D/SMP(12723):   Set on prepared listener
02-16 14:35:17.365: D/SMP(12723): Set audio stream type
02-16 14:35:17.365: D/SMP(12723): Set data source
02-16 14:35:17.435: D/SMP(12723): Prepare async
02-16 14:35:17.435: D/SMP(12723): Done!
02-16 14:35:17.445: W/MediaPlayer(12723): info/warning (1, 26)
02-16 14:35:17.445: E/MediaPlayer(12723): error (1, -4)
02-16 14:35:17.465: I/MediaPlayer(12723): Info (1,26)
02-16 14:35:17.465: E/MediaPlayer(12723): Error (1,-4)

感谢您的帮助

Answer 1

几件事。

1） 如果您希望MediaPlayer之后仍处于可用状态，则不应调用release()。-4 错误（如果我没记错的话）是一个无效的状态转换，尝试使用已发布MediaPlayer应该会产生该错误。

2） 创建MediaPlayer时，可以设置一次onPrepared、onError和onBufferingUpdate监听器。你现在正在做的事情似乎很尴尬和没有必要。

3）当您遇到Android问题时，发布日志猫输出。

如果你只是做#1，你最终可能会得到一些可行的东西。不过，在实际使用将调用回调的方法之前设置侦听器是个好主意。

编辑：

private static SingletonMediaPlayer instance;
private MediaPlayer mp;
private int buffer_state;
// Add a member for the TextView
private TextView tv_buffer_message;
private SingletonMediaPlayer() {
    Log.d("SMP","Creating new media player");
    mp = new MediaPlayer();
    Log.d("SMP","Set audio stream type");
    mp.setAudioStreamType(AudioManager.STREAM_MUSIC);
    mp.setOnErrorListener(new OnErrorListener(){
        @Override
        public boolean onError(MediaPlayer mp, int arg1, int arg2) {
            // YOU SHOULD REALLY DO SOMETHING HERE!!! IT COULD BE INFORMATIVE!!!
            return false;
        }
    });
    Log.d("SMP","  Installing buffer listener");
    mp.setOnBufferingUpdateListener(new OnBufferingUpdateListener(){
        public void onBufferingUpdate(MediaPlayer mPlayer, int percent) {
            Log.d("SMP","      Mediaplayer ready (preparation done). Inside buffer listener");
            buffer_state = percent;
            if(tv_buffer_message != null){
                tv_buffer_message.setText(percent+"%");
            }
        }
    };
    Log.d("SMP","  Set on prepared listener");
    mp.setOnPreparedListener(new OnPreparedListener() {
        public void onPrepared(MediaPlayer mPlayer) {
            Log.d("SMP","    Mediaplayer ready (preparation done). Starting reproduction");
            mPlayer.start();
            Log.d("SMP","    Mediaplayer ready (preparation done). Done!");
        }
    });
    buffer_state = 0;
}
// Remove the checkBufferState method and call the following in its place:
public setBufferMessageView(TextView tv) {
    tv_buffer_message = tv;
}
// getInstance, play, and getBufferState can stay the same, except remove the call to release