脱机时Exoplayer缓存不用于播放

使用exoplayer 2.8。1,在android SDK版本19和23上测试。

我使用以下代码构建缓存和数据源工厂:

private static final long DEFAULT_MAX_CACHE_SIZE = 20*1024*1024L;

    cacheEvictor = new LeastRecentlyUsedCacheEvictor(DEFAULT_MAX_CACHE_SIZE);

    cache = new SimpleCache(
            new File(context.getExternalCacheDir(), "exoplayer-cache"),
            cacheEvictor);

    uncachedDataSourceFactory = new OkHttpDataSourceFactory(
            new OkHttpClient(),
            "Android.ExoPlayer",
            null);
    dataSourceFactory =
            new CacheDataSourceFactory(
                    cache,
                    uncachedDataSourceFactory);

    new Thread (new Runnable () {
        public void run() {
            try {
                CacheUtil.cache(
                        new DataSpec(uri, DataSpec.FLAG_ALLOW_CACHING_UNKNOWN_LENGTH | DataSpec.FLAG_ALLOW_GZIP),
                        cache,
                        uncachedDataSourceFactory.createDataSource(),
                        null,
                        null);
            } catch (IOException e) {
                callback.invoke(false, "Error: " + e.getMessage());
            } catch (InterruptedException e) {
                callback.invoke(false, "Download interrupted");
            }
            callback.invoke(true);
        }
    }).start();

    DefaultTrackSelector trackSelector = new DefaultTrackSelector();
    player = ExoPlayerFactory.newSimpleInstance(context, trackSelector);
    mediaSource =   new ExtractorMediaSource.Factory(dataSourceFactory)
            .setContinueLoadingCheckIntervalBytes(128 * 1024)       // check whether to load more every 128KB
            .createMediaSource(uri);
    mediaSource.addEventListener(handler, new DefaultMediaSourceEventListener() {
        @Override
        public void onLoadError(int windowIndex, @Nullable MediaSource.MediaPeriodId mediaPeriodId, LoadEventInfo loadEventInfo, MediaLoadData mediaLoadData, IOException error, boolean wasCanceled) {
            Log.i(LOG_TAG, "media load error for " + uri + ": " + error);
        }
    });
    player.addListener(new Player.DefaultEventListener() {
        boolean preparing = true;
        @Override
        public void onPlayerStateChanged(boolean playWhenReady, int playbackState)
        {
            Log.i(LOG_TAG, "player " + uri + " state change " + playbackState + ", " + playWhenReady);
            switch (playbackState) {
                case Player.STATE_READY:
                    if (preparing) {
                        preparing = false;
                        callback.invoke(null, getInfo(player));
                    }
                    break;
                case Player.STATE_ENDED:
                    player.seekTo(0);
                    emitMessageEvent(playerId, "ended", "playback completed");
                    if (playerAutoDestroy.get(playerId)) {
                        Log.d(LOG_TAG, "onPlayerStateChanged(STATE_ENDED): Autodestroying player...");
                        destroy(playerId);
                    }
                    break;
                case Player.STATE_BUFFERING:
                    onLoadingChanged(true);
                    break;
            }
        }

        @Override
        public void onPlayerError(ExoPlaybackException error) {
            Log.i(LOG_TAG, "Playback error for " + uri + ": " + error.getMessage(), error);
            emitMessageEvent(playerId, "error", "Playback error: " + error.getMessage());
            destroy(playerId);
        }
   });
   player.prepare(mediaSource, true, true);

执行此操作时,我会出现几个媒体源错误,最后在日志中出现播放错误:

06-02 11:20:52.839 32762-327/com.tackta.buxton I/ExoPlayerImpl: Init 93903d2 [ExoPlayerLib/2.8.1] [generic_x86, Android SDK built for x86, unknown, 23]
06-02 11:20:52.840 32762-327/com.tackta.buxton I/AudioPlayerModule: player http://clarkesworldmagazine.com/podpress_trac/feed/2043/0/clarkesworld_06_18_tem.mp3 state change 2, false
06-02 11:20:52.844 32762-32762/com.tackta.buxton I/AudioPlayerModule: media load error for http://clarkesworldmagazine.com/podpress_trac/feed/2043/0/clarkesworld_06_18_tem.mp3: com.google.android.exoplayer2.upstream.HttpDataSource$HttpDataSourceException: Unable to connect to http://clarkesworldmagazine.com/podpress_trac/feed/2043/0/clarkesworld_06_18_tem.mp3
06-02 11:20:52.844 32762-32762/com.tackta.buxton I/AudioPlayerModule: media load error for http://clarkesworldmagazine.com/podpress_trac/feed/2043/0/clarkesworld_06_18_tem.mp3: com.google.android.exoplayer2.upstream.HttpDataSource$HttpDataSourceException: Unable to connect to http://clarkesworldmagazine.com/podpress_trac/feed/2043/0/clarkesworld_06_18_tem.mp3
06-02 11:20:53.846 32762-32762/com.tackta.buxton I/AudioPlayerModule: media load error for http://clarkesworldmagazine.com/podpress_trac/feed/2043/0/clarkesworld_06_18_tem.mp3: com.google.android.exoplayer2.upstream.HttpDataSource$HttpDataSourceException: Unable to connect to http://clarkesworldmagazine.com/podpress_trac/feed/2043/0/clarkesworld_06_18_tem.mp3
06-02 11:20:55.848 32762-32762/com.tackta.buxton I/AudioPlayerModule: media load error for http://clarkesworldmagazine.com/podpress_trac/feed/2043/0/clarkesworld_06_18_tem.mp3: com.google.android.exoplayer2.upstream.HttpDataSource$HttpDataSourceException: Unable to connect to http://clarkesworldmagazine.com/podpress_trac/feed/2043/0/clarkesworld_06_18_tem.mp3
06-02 11:20:55.858 32762-407/com.tackta.buxton E/ExoPlayerImplInternal: Source error.
06-02 11:20:55.859 32762-327/com.tackta.buxton I/AudioPlayerModule: Playback error for http://clarkesworldmagazine.com/podpress_trac/feed/2043/0/clarkesworld_06_18_tem.mp3: null
06-02 11:20:55.863 32762-327/com.tackta.buxton I/ExoPlayerImpl: Release 93903d2 [ExoPlayerLib/2.8.1] [generic_x86, Android SDK built for x86, unknown, 23] [goog.exo.core, goog.exo.okhttp]

这段代码应该从预加载的缓存访问数据,还是有原因试图联系网络服务器?有没有一种方法可以告诉它在不联系服务器的情况下使用缓存?