我想将ExoPlayer与SurfaceView和SeekBar一起使用。我从ExoPlayer演示中获取的buildTrackName函数。我想使用SeekBar来改变播放器的位置，使用listView来显示我视频的所有音轨。当我使用ExoPlayer函数来获取播放器持续时间或从视频中获取所有音轨时，这些函数对于getDuration（）返回-1，对于getTrackCount（）返回0。我试图将这些函数放在代码的不同部分，但它们仅适用于ExoPlayer.Listener的onPlayerStateChanged方法。但！在这种情况下，在所有函数之后，程序进入无限循环。
public class MainActivity extends AppCompatActivity implements SurfaceHolder.Callback{
private String videoPath = "myVideoPath";
private SurfaceView surfaceView;
private SeekBar seekBar;
private ListView listView;
private ArrayList<String> trackList;
private ArrayAdapter<String> arrayAdapter;
private ExoPlayer exoPlayer;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
surfaceView = (SurfaceView) findViewById(R.id.surfaceView);
seekBar = (SeekBar) findViewById(R.id.seekBar);
listView = (ListView) findViewById(R.id.listView);
trackList = new ArrayList<>();
arrayAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_expandable_list_item_1, audioList);
listView.setAdapter(arrayAdapter);
MediaCodecSelector mediaCodecSelector = MediaCodecSelector.DEFAULT;
Uri uri = Uri.parse(videoPath);
DataSource dataSource = new DefaultUriDataSource(this, "test");
ExtractorSampleSource extractorSampleSource = new ExtractorSampleSource(
uri, dataSource, new DefaultAllocator(64*1024), 256*64*1024,null);
MediaCodecVideoTrackRenderer videoRenderer = new MediaCodecVideoTrackRenderer(this,extractorSampleSource,mediaCodecSelector,MediaCodec.VIDEO_SCALING_MODE_SCALE_TO_FIT);
MediaCodecAudioTrackRenderer audioRenderer = new MediaCodecAudioTrackRenderer(
extractorSampleSource, mediaCodecSelector);
exoPlayer = ExoPlayer.Factory.newInstance(2);
exoPlayer.sendMessage(videoRenderer, MediaCodecVideoTrackRenderer.MSG_SET_SURFACE, surfaceView.getHolder().getSurface());
exoPlayer.prepare(videoRenderer,audioRenderer);
exoPlayer.setPlayWhenReady(true);
exoPlayer.addListener(new ExoPlayer.Listener() {
@Override
public void onPlayerStateChanged(boolean playWhenReady, int playbackState) {
if (playbackState == ExoPlayer.STATE_READY){
seekBar.setMax((int)exoPlayer.getDuration());
int trackCount = exoPlayer.getTrackCount(1);
for (int i = 0; i < trackCount; i++) {
trackList.add(buildTrackName(exoPlayer.getTrackFormat(1, i)));
}
} //infinite loop after this place
}
@Override
public void onPlayWhenReadyCommitted() {
}
@Override
public void onPlayerError(ExoPlaybackException error) {
}
});
}
///
}