使用DASH时，我的Exoplayer播放器给我一个错误

Question

06-26 12:32:30.141 16571-16980/com.example.dell.exoplayer_test E/ExoPlayerImplInternal: Source error.
    com.google.android.exoplayer2.ParserException: org.xmlpull.v1.XmlPullParserException: unterminated entity ref (position:TEXT @1:218 in java.io.InputStreamReader@c8b4a4f) 
        at com.google.android.exoplayer2.source.dash.manifest.DashManifestParser.parse(DashManifestParser.java:105)
        at com.google.android.exoplayer2.source.dash.manifest.DashManifestParser.parse(DashManifestParser.java:58)
        at com.google.android.exoplayer2.upstream.ParsingLoadable.load(ParsingLoadable.java:130)
        at com.google.android.exoplayer2.upstream.Loader$LoadTask.run(Loader.java:308)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
        at java.lang.Thread.run(Thread.java:818)
     Caused by: org.xmlpull.v1.XmlPullParserException: unterminated entity ref (position:TEXT @1:218 in java.io.InputStreamReader@c8b4a4f) 
        at org.kxml2.io.KXmlParser.readEntity(KXmlParser.java:1219)
        at org.kxml2.io.KXmlParser.readValue(KXmlParser.java:1401)
        at org.kxml2.io.KXmlParser.next(KXmlParser.java:393)
        at org.kxml2.io.KXmlParser.next(KXmlParser.java:313)
        at com.google.android.exoplayer2.source.dash.manifest.DashManifestParser.parse(DashManifestParser.java:98)
        at com.google.android.exoplayer2.source.dash.manifest.DashManifestParser.parse(DashManifestParser.java:58) 
        at com.google.android.exoplayer2.upstream.ParsingLoadable.load(ParsingLoadable.java:130) 
        at com.google.android.exoplayer2.upstream.Loader$LoadTask.run(Loader.java:308) 
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113) 
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588) 
        at java.lang.Thread.run(Thread.java:818) 

这是我的代码行。

这个方法是视频的起步

 private void initializePlayer() {
    if (player == null) {
        player = ExoPlayerFactory.newSimpleInstance(new DefaultRenderersFactory(this),
                new DefaultTrackSelector(), new DefaultLoadControl());
        playerView.setPlayer(player);
        player.setPlayWhenReady(playWhenReady);
        player.seekTo(currentWindow, playbackPosition);
    }
    prepareExoPlayer();
}

在这里使用DASH，我想问题可能在这里

  private MediaSource buildMediaSource(Uri uri) {
    DataSource.Factory dataSourceFactory =
            new DefaultHttpDataSourceFactory("ua",BANDWIDTH_METER);
    DashChunkSource.Factory dashChunkSourceFactory =
            new DefaultDashChunkSource.Factory(dataSourceFactory);
    return new DashMediaSource
            (uri, dataSourceFactory, dashChunkSourceFactory, null, null);

}

也准备其他方法，但说同样的错误

  private MediaSource buildMediaSource(Uri uri) {
    DataSource.Factory dataSourceFactory =
            new DefaultHttpDataSourceFactory("ua",BANDWIDTH_METER);
    DashChunkSource.Factory dashChunkSourceFactory =
            new DefaultDashChunkSource.Factory(dataSourceFactory);
    return new DashMediaSource
            (uri, dataSourceFactory, dashChunkSourceFactory, null, null);
}

如何解决此问题？我研究了其他类似的问题，但与此无关。