问Android Exoplayer DownloadTracker:获取离线DRM license失败

EN

我需要脱机播放受DRM保护的内容。

但是，在构建DRM会话后，会抛出以下错误：

无法获取脱机DRM许可证com.google.android.exoplayer2.drm.DrmSession$DrmSessionException: com.google.android.exoplayer2.upstream.HttpDataSource$InvalidResponseCodeException:响应代码:403at com.google.android.exoplayer2.drm.DefaultDrmSession.onError(DefaultDrmSession.java:524) at com.google.android.exoplayer2.drm.DefaultDrmSession.onKeysError(DefaultDrmSession.java:519) at com.google.android.exoplayer2.drm.DefaultDrmSession.onKeyResponse(DefaultDrmSession.java:482) at com.google.android.exoplayer2.drm.DefaultDrmSession.access$100(DefaultDrmSession.java:58) at com.google.android.exoplayer2.drm.DefaultDrmSession$ResponseHandler.handleMessage(DefaultDrmSession.java:563) at android.os.Handler.dispatchMessage(Handler.java:106) at android.os.Looper.loop(Looper.java:164) at android.os.Handler.dispatchMessage(Handler.java:106)由以下原因引起: com.google.android.exoplayer2.drm.MediaDrmCallbackException: com.google.android.exoplayer2.upstream.HttpDataSource$InvalidResponseCodeException: Response code: 403at com.google.android.exoplayer2.drm.HttpMediaDrmCallback.executePost(HttpMediaDrmCallback.java:194) at android.os.Looper.loop(Looper.java:164) at com.google.android.exoplayer2.drm.HttpMediaDrmCallback.executeKeyRequest(HttpMediaDrmCallback.java:153) at com.google.android.exoplayer2.drm.DefaultDrmSession$RequestHandler.handleMessage(DefaultDrmSession.java:602) at android.os.Handler.dispatchMessage(Handler.java:106) at android.os.Looper.loop(Looper.java:164)错误由: com.google.android.exoplayer2.upstream.HttpDataSource$InvalidResponseCodeException: Response code: 403 at com.google.android.exoplayer2.ext.cronet.CronetDataSource.引起在com.google.android.exoplayer2.upstream.StatsDataSource.open(StatsDataSource.java:84)在com.google.android.exoplayer2.upstream.DataSourceInputStream.checkOpened(DataSourceInputStream.java:101)在com.google.android.exoplayer2.upstream.DataSourceInputStream.read(DataSourceInputStream.java:81)在com.google.android.exoplayer2.upstream.DataSourceInputStream.read(DataSourceInputStream.java:75)在com.google.android.exoplayer2.util.Util.toByteArray(Util.java:174)在com.google.android打开(CronetDataSource.java:588)。exoplayer2.drm.HttpMediaDrmCallback.executePost(HttpMediaDrmCallback.java:177)在com.google.android.exoplayer2.drm.HttpMediaDrmCallback.executeKeyRequest(HttpMediaDrmCallback.java:153)在com.google.android.exoplayer2.drm.DefaultDrmSession$RequestHandler.handleMessage(DefaultDrmSession.java:602)在android.os.Handler.dispatchMessage(Handler.java:106)在android.os.Looper.loop(Looper.java:164)在android.os.HandlerThread.run(HandlerThread.java:65)