AndroId MediaPlayer prepareAsync method

问题

I have a strange problem. I use the prepareAsync method with the MediaPlayer, but the listener that I declared just never gets fired. I try to stream a live .mp3 feed from the Internet (radio station). I use an inline method for the listener, but I also tried implementing the interface without any success. Here's a portion of my code :

In the member section :

String url = "http://<my_url>.mp3";
MediaPlayer mediaPlayer = new MediaPlayer();

In Activity onCreate() :

ToggleButton playButton = (ToggleButton) findViewById(R.id.playToggleButton);
playButton.setOnClickListener(this);
playButton.clearFocus();
playButton.setClickable(false);

mediaPlayer.setOnPreparedListener(new OnPreparedListener() {
    public void onPrepared(MediaPlayer mp) {
        ToggleButton playButton = (ToggleButton) findViewById(R.id.playToggleButton);
        playButton.setClickable(true);
        mp.start();
    }
});

preparePlayer();

Then, here's the preparePlayer() method :

private void preparePlayer() {
    if (mediaPlayer == null) {
        mediaPlayer = new MediaPlayer();
    }
    mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
    try {
        mediaPlayer.setDataSource(url);
        mediaPlayer.prepareAsync();

    } catch (IllegalArgumentException e) {
        Toast.makeText(
                MyStreamActivity.this,
                getResources().getString(R.string.erreurIllegalArgument),
                Toast.LENGTH_LONG).show();
        e.printStackTrace();
    } catch (IllegalStateException e) {
        Toast.makeText(
                MyStreamActivity.this,
                getResources().getString(R.string.erreurIllegalState),
                Toast.LENGTH_LONG).show();
        e.printStackTrace();
    } catch (IOException e) {
        Toast.makeText(
                MyStreamActivity.this,
                getResources().getString(R.string.erreurIO),
                Toast.LENGTH_LONG).show();
        e.printStackTrace();
    }
}

And (just for the record), the onDetroy() where I do the cleaning :

private void releaseMediaPlayer() {
    if (mediaPlayer != null) {
        if(mediaPlayer.isPlaying()) {
            mediaPlayer.stop();
        }
        mediaPlayer.release();
        mediaPlayer = null;
    }
}

@Override
protected void onDestroy() {
    super.onDestroy();
    releaseMediaPlayer();
}

回答1:

You are setting the OnPreparedListener in your Activity's create method and later on, possibly, creating a new MediaPlayer in your preparePlayer() method. Any newly created MediaPlayer's wont have the prepareListener set. You should also add an errorlistener to find out whats going on.

You may want to move the setOnPreparedListener call inside the

  if (mediaPlayer == null) {
    mediaPlayer = new MediaPlayer();
}

as well as setting a setOnErrorListener like so:

if (mediaPlayer == null) {
    mediaPlayer = new MediaPlayer();
    mediaPlayer.setOnErrorListener(....);
    mediaPlayer.setOnPreparedListener(new OnPreparedListener() {
        public void onPrepared(MediaPlayer mp) {
            ToggleButton playButton = (ToggleButton) findViewById(R.id.playToggleButton);
            playButton.setClickable(true);
            mp.start();
        }
    });
}

Please change e.printStackTrace(); to

Log.e("tag", e.getMessage(), e);

Hope this helps, let us know if you have any log data as this will also be useful.

回答2:

Turned out, I forgot to mention the "@Override" on top of my inner method. Like this :

mediaPlayer.setOnPreparedListener(new OnPreparedListener() {
    @Override
    public void onPrepared(MediaPlayer mp) {
        ToggleButton playButton = (ToggleButton) findViewById(R.id.playToggleButton);
        playButton.setClickable(true);
        mp.start();
    }
});

Now everything works fine. Well... almost, since it takes forever to buffer...

来源：https://stackoverflow.com/questions/10307131/android-mediaplayer-prepareasync-method

标签

android

asynchronous

android-mediaplayer

prepare