Using cache in ExoPlayer

Here is the solution for ExoPlayer 2.+

Create a custom cache data source factory

public class CacheDataSourceFactory implements DataSource.Factory {
    private final Context context;
    private final DefaultDataSourceFactory defaultDatasourceFactory;
    private final long maxFileSize, maxCacheSize;

    public CacheDataSourceFactory(Context context, long maxCacheSize, long maxFileSize) {
        super();
        this.context = context;
        this.maxCacheSize = maxCacheSize;
        this.maxFileSize = maxFileSize;
        String userAgent = Util.getUserAgent(context, context.getString(R.string.app_name));
        DefaultBandwidthMeter bandwidthMeter = new DefaultBandwidthMeter();
        defaultDatasourceFactory = new DefaultDataSourceFactory(this.context,
                bandwidthMeter,
                new DefaultHttpDataSourceFactory(userAgent, bandwidthMeter));
    }

    @Override
    public DataSource createDataSource() {
        LeastRecentlyUsedCacheEvictor evictor = new LeastRecentlyUsedCacheEvictor(maxCacheSize);
        SimpleCache simpleCache = new SimpleCache(new File(context.getCacheDir(), "media"), evictor);
        return new CacheDataSource(simpleCache, defaultDatasourceFactory.createDataSource(),
                new FileDataSource(), new CacheDataSink(simpleCache, maxFileSize),
                CacheDataSource.FLAG_BLOCK_ON_CACHE | CacheDataSource.FLAG_IGNORE_CACHE_ON_ERROR, null);
    }
}

And the player

BandwidthMeter bandwidthMeter = new DefaultBandwidthMeter();
TrackSelection.Factory videoTrackSelectionFactory =
        new AdaptiveTrackSelection.Factory(bandwidthMeter);
TrackSelector trackSelector = new DefaultTrackSelector(videoTrackSelectionFactory);

SimpleExoPlayer exoPlayer = ExoPlayerFactory.newSimpleInstance(this, trackSelector);
MediaSource audioSource = new ExtractorMediaSource(Uri.parse(url),
            new CacheDataSourceFactory(context, 100 * 1024 * 1024, 5 * 1024 * 1024), new DefaultExtractorsFactory(), null, null);
exoPlayer.setPlayWhenReady(true); 
exoPlayer.prepare(audioSource);

It works pretty well.