Question

这是我播放和更新曲目的代码，按下按钮我调用update()功能，但曲目没有正确更改。

第一首曲目播放得很好，但是当我尝试切换到下一首时，它表现不正确，我错了。

MediaPlayer mPlayer;


        @Override
        public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mPlayer=new MediaPlayer();
        mPlayer.setOnPreparedListener(this);
        }

         public void prepareMediaPlayer(FileDescriptor fd)
         {
             try {
                 mPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
                 Log.d("player", "setAudiotStreamType");
                 mPlayer.setDataSource(fd); 
                 Log.d("player", "setDataSource");
                 mPlayer.prepareAsync();
                 Log.d("player", "prepareAsync");

             } 
             catch (IOException e) {}
             catch (IllegalArgumentException e) {} 
             catch (IllegalStateException e) {}
         }

        @Override
        public void onPrepared(MediaPlayer arg0) {
        }

        public void updateTrack()
        {
                        File f=(File) imageFilexxSm.values().toArray()[index];
                    FileInputStream inputStream = new FileInputStream(f);
                    prepareMediaPlayer(inputStream.getFD());
                    inputStream.close();

                    if(mPlayer.isPlaying())
                    {   
                    mPlayer.stop();
                    mPlayer.reset();
                    mPlayer.reset();
                    }

                    else
                    {
                    mPlayer.start();    
                    }   

        }

日志：

05-11 13:17:42.782: E/MediaPlayer(14969): start called in state 4
05-11 13:17:42.782: E/MediaPlayer(14969): error (-38, 0)
05-11 13:17:42.821: I/dalvikvm-heap(14969): Grow heap (frag case) to 34.372MB for 4194320-byte allocation
05-11 13:17:43.040: I/System.out(14969): index value is 0/1024/0
05-11 13:17:43.087: I/dalvikvm-heap(14969): Grow heap (frag case) to 30.457MB for 2261008-byte allocation
05-11 13:17:43.189: E/MediaPlayer(14969): attachNewPlayer called in state 8
05-11 13:17:43.220: I/Choreographer(14969): Skipped 35 frames!  The application may be doing too much work on its main thread.
05-11 13:17:43.275: I/dalvikvm-heap(14969): Grow heap (frag case) to 34.452MB for 4194320-byte allocation
05-11 13:17:43.392: I/MediaPlayer(14969): Don't send intent. msg.arg1 = 0, msg.arg2 = 0
05-11 13:17:43.392: E/MediaPlayer(14969): Error (-38,0)
05-11 13:17:57.642: I/System.out(14969): action down
05-11 13:17:57.642: I/System.out(14969): points 1.6014493?21
05-11 13:17:57.642: I/System.out(14969): show one page
05-11 13:17:57.642: I/System.out(14969): start curl right
05-11 13:17:57.650: I/System.out(14969): index value is 1/1024/1
05-11 13:17:57.681: I/dalvikvm-heap(14969): Grow heap (frag case) to 30.401MB for 2261008-byte allocation
05-11 13:17:57.775: E/MediaPlayer(14969): attachNewPlayer called in state 128
05-11 13:17:57.821: I/dalvikvm-heap(14969): Grow heap (frag case) to 34.401MB for 4194320-byte allocation
05-11 13:18:04.704: I/System.out(14969): action down
05-11 13:18:04.704: I/System.out(14969): points 1.692029?21
05-11 13:18:04.704: I/System.out(14969): show one page
05-11 13:18:04.704: I/System.out(14969): start curl right
05-11 13:18:04.704: I/System.out(14969): index value is 2/1024/2
05-11 13:18:04.736: I/dalvikvm-heap(14969): Grow heap (frag case) to 30.315MB for 2261008-byte allocation
05-11 13:18:04.829: E/MediaPlayer(14969): attachNewPlayer called in state 128
05-11 13:18:04.876: I/dalvikvm-heap(14969): Grow heap (frag case) to 34.316MB for 4194320-byte allocation
05-11 13:18:08.845: I/System.out(14969): action down
05-11 13:18:08.845: I/System.out(14969): points 1.5471015?21
05-11 13:18:08.845: I/System.out(14969): show one page
05-11 13:18:08.845: I/System.out(14969): start curl right
05-11 13:18:08.845: I/System.out(14969): index value is 3/1024/3
05-11 13:18:08.876: I/dalvikvm-heap(14969): Grow heap (frag case) to 30.316MB for 2261008-byte allocation
05-11 13:18:08.970: E/MediaPlayer(14969): attachNewPlayer called in state 16
05-11 13:18:09.025: I/dalvikvm-heap(14969): Grow heap (frag case) to 34.316MB for 4194320-byte allocation
05-11 13:18:12.892: I/System.out(14969): action down
05-11 13:18:12.892: I/System.out(14969): points 1.5688405?21
05-11 13:18:12.892: I/System.out(14969): show one page
05-11 13:18:12.892: I/System.out(14969): start curl right
05-11 13:18:12.892: I/System.out(14969): index value is 4/1024/4
05-11 13:18:12.923: I/dalvikvm-heap(14969): Grow heap (frag case) to 30.316MB for 2261008-byte allocation
05-11 13:18:13.025: E/MediaPlayer(14969): start called in state 4
05-11 13:18:13.025: E/MediaPlayer(14969): error (-38, 0)
05-11 13:18:13.064: I/dalvikvm-heap(14969): Grow heap (frag case) to 34.316MB for 4194320-byte allocation
05-11 13:18:13.126: E/MediaPlayer(14969): Error (-38,0)
05-11 13:18:13.126: I/MediaPlayer(14969): Don't send intent. msg.arg1 = 0, msg.arg2 = 0
05-11 13:18:18.228: I/System.out(14969): action down
05-11 13:18:18.236: I/System.out(14969): points -1.5289855?21
05-11 13:18:18.236: I/System.out(14969): show one page
05-11 13:18:18.236: I/System.out(14969): index value is 3/1024/3
05-11 13:18:18.259: I/dalvikvm-heap(14969): Grow heap (frag case) to 30.316MB for 2261008-byte allocation
05-11 13:18:18.353: E/MediaPlayer(14969): attachNewPlayer called in state 8
05-11 13:18:18.400: I/dalvikvm-heap(14969): Grow heap (frag case) to 34.316MB for 4194320-byte allocation

Answer 1

有两件事情发生了：

您使用的是prepareAsync，异步。也就是说，在执行任何依赖于准备工作的事情之前（例如调用onPrepared），您应该等待start回调。这就是您收到“start called in state 4”错误消息的原因（状态4为MEDIA_PLAYER_PREPARING）。
如果在正在播放期间调用updateTrack，则在准备新歌之前，似乎不会停止MediaPlayer。在调用stop 之后，您已拨打prepareMediaPlayer ，但这对您没有多大帮助。为了能够重新准备播放器，您必须首先stop播放，如果您还想更改数据源，则必须在停止播放后reset播放器。

有关有效状态转换的集合，请参阅MediaPlayer documentation's state diagram。

媒体播放器跟踪更改问题

1 个答案: