gistfile1.java

/* sample code, 实现不完整. 可能要用service实现, 但是接口相同 */

// 先不用去想怎么实现, 先想我在Activity和UI会怎么用 audio player
// 1. 因为需要能够自动切换到下一首, 所以生成播放器需要一个播放列表
// 2. 在播放的时候, UI需要根据播放器的状态显示不同的UI, 所以需要监听AudioPlayer的状态
// 3. 因为需要能够播放任意一首歌曲, 需要play(int index)

public class AudioListPlayer {

    // 我们在UI上只需要这四个状态, 那么就只监听这些状态
    public static interface AudioPlayerListener {
        public void onReady(); // 当缓冲完毕的时候
        public void onProgress(int percentage);
        public void onStartBuffer(); // 当音频需要缓冲才能播放的时候
        public void onStop(); // 当播放完毕的时候
        public void onNext(int index); // 当切换到下一首
    }
    
    private AudioPlayerListener audioPlayerListener;

    // 因为需要能够自动切换到下一首, 所以生成播放器需要一个播放列表
    private audios;
    public AudioListPlayer(List<Audio> audios) {

    }

    MediaPlayer player;
    
    int playingIndex;
    
    public void play(int index) {
        playingIndex = index;
        
        Audio audio = audios.get(index);
        String audioUrl = audio.getContentUrl();
        
        player = new MediaPlayer();
        // init format... and other code....
        player.setDataSource(audioUrl);
        player.setOnPreparedListerner(new OnPreparedListener() {
            public void onPrepared(MediaPlayer mp) {
                audioPlayerListener.onReady();
            }
        });

        player.setOnSeekCompletionListener(new OnSeekCompletionListner() {
            public void onSeekComplete(MediaPlayer mp) {
                audioPlayerListener.onReady()
            }
        });

        player.setOnCompletionListener(new OnCompletionListener() { 
            if ( hasNext() ) { 
                audioPlayerListener.onNext(playingIndex + 1); 
                playNext();
            } else {
                audioPlayerListener.onStop();
            }
        });
        
        player.onStartBuffer();
        player.prepareAsync();
    }
    
    public void seek(int second) {
        audioPlayerListener.onStartBuffer();
        player.seekTo(second);
    }
    
    public void playNext() {
        if (hasNext()) {
            play(playingIndex + 1);
        }
    }
    
    public void playPrevious() {
        if (hasPrevious()) {
            play(playingIndex - 1);
        }
    }
    
    private boolean hasPrevious() {
        playingIndex > 0;
    }
    
    private boolean hasNext() {
        playingIndex <= audios.size();
    }
}