安卓Exoplayer音频播放异常

Question

我在使用ExoPlayer播放音频时遇到了问题。具体来说，在快速切换“停止 - 开始”时会出现异常。

java.lang.NullPointerException: Attempt to invoke interface method 'void com.google.android.exoplayer2.source.MediaSource$Listener.onSourceInfoRefreshed(com.google.android.exoplayer2.Timeline, java.lang.Object)' on a null object reference.

这是我的代码。我做错了什么？对不起，我的英语不好。非常感谢大家的帮助!

@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    startPosition = getArguments().getInt("startPosition");
    Log.i("igor", "start position= " + startPosition);
    sounds = (ArrayList<SoundModel>) getArguments().getSerializable("sounds");
    utils = new Utils();
    View view = inflater.inflate(R.layout.play_layout, container, false);
    initializePlayer();
    prepareExoPlayer(startPosition);
    initViews(view);
    settingsToolbar(view);
    return view;
}

private void settingsToolbar(View view) {
    toolbar = (Toolbar) view.findViewById(R.id.toolbar);
    ((AppCompatActivity) getActivity()).setSupportActionBar(toolbar);
    ((AppCompatActivity) getActivity()).getSupportActionBar().setHomeButtonEnabled(true);
    ((AppCompatActivity) getActivity()).getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    ((AppCompatActivity) getActivity()).getSupportActionBar().setDisplayShowTitleEnabled(false);
    setHasOptionsMenu(true);
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch(item.getItemId()){
        case android.R.id.home:
            getActivity().onBackPressed();
    }
    return super.onOptionsItemSelected(item);
}


private void initViews(View view) {
    mPickerTags = (ColectionTags) view.findViewById(R.id.colection_tags);
    imNext = (ImageView) view.findViewById(R.id.imNext);
    imPlay = (ImageView) view.findViewById(R.id.imPlay);
    imPrev = (ImageView) view.findViewById(R.id.imPrev);
    soundSeekBar = (SeekBar) view.findViewById(R.id.soundProgressBar);
    songCurrentDurationLabel = (TextView) view.findViewById(R.id.songCurrentDurationLabel);
    songTotalDurationLabel = (TextView) view.findViewById(R.id.songTotalDurationLabel);
    tvCountSounds = (TextView) view.findViewById(R.id.tvCountSounds);
    settingsViews();
}

private void settingsViews() {
    soundSeekBar.setOnSeekBarChangeListener(this);
    soundSeekBar.setProgress(0);
    soundSeekBar.setMax(100);
    soundSeekBar.setClickable(true);
    soundSeekBar.setFocusable(true);
    soundSeekBar.setEnabled(true);
    imNext.setOnClickListener(this);
    imPlay.setOnClickListener(this);
    imPrev.setOnClickListener(this);
    tvCountSounds.setText((startPosition+1)+"/"+sounds.size());
    tagsSet();
}

private void tagsSet() {
    mPickerTags.clearItems();
    mPickerTags.setItems(generateItems());
    mPickerTags.drawItemView();
    mPickerTags.setOnItemClickListener(new OnItemClickListener() {
        @Override
        public void onClick(Item item, int position) {
            showFragment(getActivity(), SearchListFragment.newInstance(item.text));
        }
    });
}

@Override
public void onStart() {
    super.onStart();

}

private void initializePlayer() {
    userAgent = Util.getUserAgent(getActivity(), "ExoPlayerDemo");
    mainHandler = new Handler();
    BandwidthMeter bandwidthMeter = new DefaultBandwidthMeter();
    TrackSelection.Factory videoTrackSelectionFactory = new AdaptiveVideoTrackSelection.Factory(bandwidthMeter);
    TrackSelector trackSelector = new DefaultTrackSelector(mainHandler, videoTrackSelectionFactory);


    LoadControl loadControl = new DefaultLoadControl();


    player = ExoPlayerFactory.newSimpleInstance(getActivity(), trackSelector, loadControl);


    //////
    bwMeter = new DefaultBandwidthMeter();
    dataSourceFactory = new DefaultDataSourceFactory(getActivity(),
            Util.getUserAgent(getActivity(), "yourApplicationName"), bwMeter);
    extractorsFactory = new DefaultExtractorsFactory();
}

private void prepareExoPlayer(int position) {
    uri = Uri.parse(sounds.get(position).getSoundLink());
    MediaSource mediaSource = new ExtractorMediaSource(uri,
            dataSourceFactory, extractorsFactory, mainHandler, null);
    try {
        mediaSource.maybeThrowSourceInfoRefreshError();
    } catch (IOException e) {
        e.printStackTrace();
        Log.i("igor","exept= "+e.getMessage());
    }

        player.prepare(mediaSource);


    player.addListener(new ExoPlayer.EventListener() {
        @Override
        public void onLoadingChanged(boolean isLoading) {

        }

        @Override
        public void onPlayerStateChanged(boolean playWhenReady, int playbackState) {
            switch (playbackState){
                case ExoPlayer.STATE_ENDED:
                  // onNextPlaySound();
                    break;
                case ExoPlayer.STATE_READY:
                    Log.i("igor","is read");
                    break;
                case ExoPlayer.STATE_IDLE:
                    break;
                case ExoPlayer.STATE_BUFFERING:
                    break;

            }
        }

        @Override
        public void onTimelineChanged(Timeline timeline, Object manifest) {
        }

        @Override
        public void onPlayerError(ExoPlaybackException error) {
            //Toast.makeText(getActivity(),"Play error",Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onPositionDiscontinuity() {

        }
    });
}

@Override
public void onResume() {
    super.onResume();
}

@Override
public void onPause() {
    super.onPause();
}


@Override
public void onStop() {
    super.onStop();
    player.setPlayWhenReady(false);
    player.release();
}

@Override
public void onLoadError(IOException error) {

}

@Override
public void onClick(View v) {
    switch (v.getId()) {
        case R.id.imPlay:
            if(isPlaying==false) {
                prepareExoPlayer(startPosition);
                player.setPlayWhenReady(true);
                player.seekTo(currentPos);
                soundSeekBar.setProgress(currentProgress);
                isPlaying=player.getPlayWhenReady();
                imPlay.setImageDrawable(getResources().getDrawable(R.drawable.pause));
                updateProgressBar(currentProgress);
            }
            else {
                currentProgress= soundSeekBar.getProgress();
                currentPos = player.getCurrentPosition();
                player.setPlayWhenReady(false);
                isPlaying=player.getPlayWhenReady();
                imPlay.setImageDrawable(getResources().getDrawable(R.drawable.play));
            }
            break;
        case R.id.imNext:
            Log.i("igor","Ready player= "+player.getPlayWhenReady());
            onNextPlaySound();
            break;
        case R.id.imPrev:
            Log.i("igor","Ready player= "+player.getPlayWhenReady());
            onPrevPlaySound();
            break;

    }
}

private void onPrevPlaySound() {
    if (startPosition > 0) {
        startPosition--;
        prepareExoPlayer(startPosition);
        tagsSet();
        tvCountSounds.setText((startPosition+1)+"/"+sounds.size());
    }
    player.setPlayWhenReady(true);
}

private void onNextPlaySound() {
    if (startPosition < sounds.size()-1) {
        startPosition++;
        prepareExoPlayer(startPosition);
        tagsSet();
        tvCountSounds.setText((startPosition+1)+"/"+sounds.size());
    }
    player.setPlayWhenReady(true);
}

public void updateProgressBar(int currentProgress) {
    mHandler.postDelayed(mUpdateTimeTask, 10);
}


private Runnable mUpdateTimeTask = new Runnable() {
    public void run() {
        long currentDuration=currentProgress;
        if(null!=player) {
            currentDuration = player.getCurrentPosition();
            if(player.getDuration()>0) {
                totalDuration = player.getDuration();
            }
            //player.getDuration()>0?totalDuration=player.getDuration():;
        }

        songTotalDurationLabel.setText(""+utils.milliSecondsToTimer(totalDuration));

        songCurrentDurationLabel.setText(""+utils.milliSecondsToTimer(currentDuration));

        // Updating progress bar
        int progress = (int)(utils.getProgressPercentage(currentDuration, totalDuration));
        //Log.d("Progress", ""+progress);
        soundSeekBar.setProgress(progress);

        mHandler.postDelayed(this, 10);

    }
};


@Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {

}

@Override
public void onStartTrackingTouch(SeekBar seekBar) {

}

@Override
public void onStopTrackingTouch(SeekBar seekBar) {
    mHandler.removeCallbacks(mUpdateTimeTask);
   int currentPosition = utils.progressToTimer(seekBar.getProgress(), (int) totalDuration);

     //forward or backward to certain seconds
    player.seekTo(currentPosition);

    /// update timer progress again
    updateProgressBar(currentPosition);
}

private List<Item> generateItems() {
    SoundModel currentSound = sounds.get(startPosition);
    List<Item> items = new ArrayList<>();
    for(int i = 0; i<currentSound.getTags().size(); i++){
        items.add(new Item(currentSound.getId().toString(),currentSound.getTags().get(i)));
    }
    return items;
}

- Игорь Е

Answer 1

每次想要暂停/恢复播放时，为什么要重新创建 MediaSource？如果你想要播放一系列的声音，请使用 ConcatenatingMediaSource。此外，每次点击播放按钮时，你都会通过 addListener 添加一个新的监听器到播放器中，我认为这可能是不必要的。

我认为异常被抛出是因为你每次都在使用新的媒体资源，如果你想要多个音效，请尝试使用 ConcatenatingMediaSource，否则你应该尽量避免每次重新创建它。

- damian