选择新曲目时，Exoplayer更改曲目

Question

我正在使用一项服务来播放音乐，因此，当我第一次从某个活动启动该服务并退出该服务时，它会在后台正常播放，但是当我启动另一项音乐并退出后台时，会停止播放这种情况的任何想法吗？

public class AudioPlayerService extends Service implements Player.EventListener {

    private final IBinder mBinder = new LocalBinder();
    private SimpleExoPlayer player;
    private Item item;
    private PlayerNotificationManager playerNotificationManager;

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

    @Override
    public void onDestroy() {
        releasePlayer();
        super.onDestroy();
    }

    private void releasePlayer() {
        if (player != null) {
            playerNotificationManager.setPlayer(null);
            player.release();
            player = null;
            stopSelf();
        }
    }

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return mBinder;
    }

    public SimpleExoPlayer getPlayerInstance() {
        if (item != null && player == null && !TextUtils.isEmpty(item.getUrl())) {
            startPlayer();
        }
        return player;
    }


    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        releasePlayer();
        Bundle b = intent.getBundleExtra(AppConstants.BUNDLE_KEY);
        if (b != null) {
            item = b.getParcelable(AppConstants.ITEM_KEY);
        }
        if (item != null && player == null && !TextUtils.isEmpty(item.getUrl())) {
            startPlayer();
        }
        String action = intent.getAction();
        if (player != null) {
            if (!TextUtils.isEmpty(action) && action.equalsIgnoreCase(ACTION_PLAY)) {
                player.setPlayWhenReady(true);

            }
            if (!TextUtils.isEmpty(action) && action.equalsIgnoreCase(ACTION_PAUSE)) {
                player.setPlayWhenReady(false);
            }
        }
        return START_STICKY;
    }

    private void startPlayer() {
        final Context context = this;
        Uri uri = Uri.parse(item.getUrl());
        player = ExoPlayerFactory.newSimpleInstance(context, new DefaultTrackSelector());
        DefaultDataSourceFactory dataSourceFactory = new DefaultDataSourceFactory(context,
                Util.getUserAgent(context, getString(R.string.app_name)));
        CacheDataSourceFactory cacheDataSourceFactory = new CacheDataSourceFactory(
                CommonUtils.getCache(context),
                dataSourceFactory,
                CacheDataSource.FLAG_IGNORE_CACHE_ON_ERROR);
        MediaSource mediaSource = new ExtractorMediaSource.Factory(cacheDataSourceFactory)
                .createMediaSource(uri);
        player.prepare(mediaSource);
        player.addListener(this);
        player.setPlayWhenReady(true);
        playerNotificationManager = PlayerNotificationManager.createWithNotificationChannel(context, AppConstants.PLAYBACK_CHANNEL_ID,
                R.string.playback_channel_name,
                AppConstants.PLAYBACK_NOTIFICATION_ID,
                new PlayerNotificationManager.MediaDescriptionAdapter() {
                    @Override
                    public String getCurrentContentTitle(Player player) {
                        return item.getTitle();
                    }

                    @Nullable
                    @Override
                    public PendingIntent createCurrentContentIntent(Player player) {
                        Intent intent = new Intent(context, PlayerActivity.class);
                        Bundle serviceBundle = new Bundle();
                        serviceBundle.putParcelable(AppConstants.ITEM_KEY, item);
                        intent.putExtra(AppConstants.BUNDLE_KEY, serviceBundle);
                        return PendingIntent.getActivity(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
                    }

                    @Nullable
                    @Override
                    public String getCurrentContentText(Player player) {
                        return item.getSummary();
                    }

                    @Nullable
                    @Override
                    public Bitmap getCurrentLargeIcon(Player player, PlayerNotificationManager.BitmapCallback callback) {
                        return null;
                    }
                }
        );
        playerNotificationManager.setNotificationListener(new PlayerNotificationManager.NotificationListener() {
            @Override
            public void onNotificationStarted(int notificationId, Notification notification) {
                startForeground(notificationId, notification);
            }

            @Override
            public void onNotificationCancelled(int notificationId) {
                stopSelf();
            }
        });
        playerNotificationManager.setPlayer(player);
    }

    private void updateWidget(boolean playWhenReady) {
        Intent intent = new Intent(this, PlayerWidget.class);
        intent.setAction(AppWidgetManager.ACTION_APPWIDGET_UPDATE);
        int[] ids = AppWidgetManager.getInstance(getApplication())
                .getAppWidgetIds(new ComponentName(getApplication(), PlayerWidget.class));
        intent.putExtra(AppWidgetManager.EXTRA_APPWIDGET_IDS, ids);
        Bundle serviceBundle = new Bundle();
        serviceBundle.putParcelable(AppConstants.ITEM_KEY, item);
        intent.putExtra(AppConstants.BUNDLE_KEY, serviceBundle);
        intent.putExtra(PlayerWidget.WIDGET_PLAYING_EXTRA, playWhenReady);
        sendBroadcast(intent);
    }

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

    }

    @Override
    public void onTracksChanged(TrackGroupArray trackGroups, TrackSelectionArray trackSelections) {

    }

    @Override
    public void onLoadingChanged(boolean isLoading) {

    }

    @Override
    public void onPlayerStateChanged(boolean playWhenReady, int playbackState) {
        updateWidget(playWhenReady);
    }

    @Override
    public void onRepeatModeChanged(int repeatMode) {

    }

    @Override
    public void onShuffleModeEnabledChanged(boolean shuffleModeEnabled) {

    }

    @Override
    public void onPlayerError(ExoPlaybackException error) {

    }

    @Override
    public void onPositionDiscontinuity(int reason) {

    }

    @Override
    public void onPlaybackParametersChanged(PlaybackParameters playbackParameters) {

    }

    @Override
    public void onSeekProcessed() {

    }

    public class LocalBinder extends Binder {
        public AudioPlayerService getService() {
            return AudioPlayerService.this;
        }
    }
}

这是我的playerActivity

    public class PlayerActivity extends BaseActivity {

    @BindView(R.id.video_view)
    PlayerView mPlayerView;
    @BindView(R.id.tvTitle)
    TextView mTvTitle;
    @BindView(R.id.tvSummary)
    TextView mTvSummary;
    @BindView(R.id.ivThumbnail)
    ImageView mIvThumb;
    @BindView(R.id.adView)
    AdView mAdView;
    private String mTitle;
    private String mSummary;
    private String mImage;
    private AudioPlayerService mService;
    private Intent intent;
    private String shareableLink;
    private boolean mBound = false;

    private ServiceConnection mConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
            AudioPlayerService.LocalBinder binder = (AudioPlayerService.LocalBinder) iBinder;
            mService = binder.getService();
            mBound = true;
            initializePlayer();
        }

        @Override
        public void onServiceDisconnected(ComponentName componentName) {
            mBound = false;
        }
    };

    @SuppressLint("MissingSuperCall")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        onCreate(savedInstanceState, R.layout.activity_player);
        Bundle b = getIntent().getBundleExtra(AppConstants.BUNDLE_KEY);
        if (b != null) {
            Item item = b.getParcelable(AppConstants.ITEM_KEY);
            shareableLink = b.getString(AppConstants.SHARE_KEY);
            String mUrl = item.getUrl();
            mImage = item.getImage();
            mTitle = item.getTitle();
            mSummary = item.getSummary();
            intent = new Intent(this, AudioPlayerService.class);
            Bundle serviceBundle = new Bundle();
            serviceBundle.putParcelable(AppConstants.ITEM_KEY, item);
            intent.putExtra(AppConstants.BUNDLE_KEY, serviceBundle);
            Util.startForegroundService(this, intent);
            mPlayerView.setUseController(true);
            mPlayerView.showController();
            mPlayerView.setControllerAutoShow(true);
            mPlayerView.setControllerHideOnTouch(false);
        }
        AdRequest adRequest = new AdRequest.Builder().build();
        mAdView.loadAd(adRequest);
    }

    private void initializePlayer() {
        if (mBound) {
            SimpleExoPlayer mPlayer = mService.getPlayerInstance();
            mPlayerView.setPlayer(mPlayer);
        }
    }

    @Override
    public void onStart() {
        super.onStart();
        bindService(intent, mConnection, Context.BIND_AUTO_CREATE);
        initializePlayer();
        setUI();
    }

    private void setUI() {
        mTvTitle.setText(mTitle);
        mTvSummary.setText(Html.fromHtml(mSummary));
        GlideApp.with(this)
                .load(mImage)
                .placeholder(R.drawable.about_background)
                .diskCacheStrategy(DiskCacheStrategy.ALL)
                .into(mIvThumb);
    }

    @Override
    protected void onStop() {
        unbindService(mConnection);
        mBound = false;
        super.onStop();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.player_menu, menu);
        return super.onCreateOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.share_podcast:
                Intent shareIntent = new Intent();
                shareIntent.setAction(Intent.ACTION_SEND);
                shareIntent.putExtra(Intent.EXTRA_SUBJECT, mTitle);
                shareIntent.putExtra(Intent.EXTRA_TEXT, mTitle + "\n\n" + shareableLink);
                shareIntent.setType("text/plain");
                startActivity(Intent.createChooser(shareIntent, getString(R.string.share_text)));
                return true;
            case android.R.id.home:
                onBackPressed();
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }

    @Override
    public void onToolBarSetUp(Toolbar toolbar, ActionBar actionBar) {
        TextView tvHeader = toolbar.findViewById(R.id.tvClassName);
        tvHeader.setText(R.string.app_name);
    }
}

即使我退出活动，音乐也应该正在播放，这是我第一次选择音乐时正确进行的，但是当我已经在播放背景音乐的同​​时重新选择了另一首曲目时，它会更改曲目，但是一旦退出服务停止的活动。