android - ExoPlayer发布后如何重新初始化？

Question

我有 ExoPlayerWrapper 类，它是 ExoPlayer 的包装器，由 Dagger 单例注入(inject)。 ExoPlayerWrapper 类中的初始化 block 如下所示:

@Singleton
class ExoPlayerWrapper @Inject constructor(
    context: Context,
    userAgentInfo: UserAgentInfo
) {
    private val exoPlayer: ExoPlayer
    private val httpDataSource: HttpDataSource
    private val mediaSourceFactory: ExtractorMediaSource.Factory

    override val exoPlayerInstance: ExoPlayer
        get() = exoPlayer

   init {
        ...
        exoPlayer = ExoPlayerFactory.newSimpleInstance(renderersFactory, trackSelector)
        httpDataSource = CustomHttpDataSource(userAgentInfo.userAgent, null)
        mediaSourceFactory = ExtractorMediaSource.Factory { httpDataSource }
        state = Player.STATE_IDLE
    }

   override fun playFromUrl(uri: Uri, headers: Map<String, String>) {
        reset()
        ...
        val mediaSource = mediaSourceFactory.createMediaSource(uri)
        exoPlayer.prepare(mediaSource)
        exoPlayer.playWhenReady = true
    }

    override fun pause() {
        exoPlayer.playWhenReady = false
    }

    override fun reset() {
       stop()
       state = Player.STATE_IDLE
    }

    override fun stop() {
       exoPlayer.stop()
       exoPlayer.seekTo(0)
    }

    override fun seekTo(position: Long) {
       exoPlayer.seekTo(position)
    }

    ...

    override fun release() {
        exoPlayer.release()
        state = Player.STATE_RELEASED
    }

在 Activity 的 onCreate() 方法中，我有以下代码:

public override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_video_player)
    ...
    if (savedInstanceState != null) {
        initialized = savedInstanceState.getBoolean(INITIALIZED)
    } 
    if (!initialized) {
        val uri = Uri.parse(attachedVideo?.uri)
        player.playFromUrl(uri, sessionStore.sessionHeaders)
        videoView.requestFocus()
        initialized = true
    }

    videoView.player = player.exoPlayerInstance

    backBtn.setOnClickListener{ _ ->
        player.release()
        finish()
    }
}

但在这种情况下，我只能在点击 backBtn 按钮后播放一个视频，其他视频在我关闭应用程序并再次重新打开应用程序之前不会播放。如果我按以下方式更改 backBtn 的 OnClickListener:

backBtn.setOnClickListener{ _ ->
    player.pause()
    finish()
}

一切正常，点击 backBtn 按钮后可以播放其他视频。因此，在 release() 方法调用之后重新初始化 ExoPlayer 似乎是个问题。 ExoPlayer 发布后如何正确重新初始化？

UPD 在调用 release() 并尝试再次打开视频后，我在 Logcat 中看到以下错误:

java.lang.IllegalStateException: Handler (android.os.Handler) {81fa8ef} sending message to a Handler on a dead thread
    at android.os.MessageQueue.enqueueMessage(MessageQueue.java:545)
    at android.os.Handler.enqueueMessage(Handler.java:661)
    at android.os.Handler.sendMessageAtTime(Handler.java:630)
    at android.os.Handler.sendMessageDelayed(Handler.java:600)
    at android.os.Handler.sendMessage(Handler.java:537)
    at android.os.Message.sendToTarget(Message.java:418)
    at com.google.android.exoplayer2.ExoPlayerImplInternal.stop(ExoPlayerImplInternal.java:207)
    at com.google.android.exoplayer2.ExoPlayerImpl.stop(ExoPlayerImpl.java:357)
    at com.google.android.exoplayer2.SimpleExoPlayer.stop(SimpleExoPlayer.java:777)
    at com.google.android.exoplayer2.SimpleExoPlayer.stop(SimpleExoPlayer.java:772)
    at package.ExoPlayerWrapper.stop(ExoPlayerWrapper.kt:xx)
    at package.ExoPlayerWrapper.reset(ExoPlayerWrapper.kt:xx)
    at package.ExoPlayerWrapper.playFromUrl(ExoPlayerWrapper.kt:xx)
    at package.VideoPlayerActivity.onCreate(VideoPlayerActivity.kt:xx)

Answer 1

此问题是由于尝试使用资源已被释放的播放器而产生的。因为:

exoPlayer = ExoPlayerFactory.newSimpleInstance(renderersFactory, trackSelector)

仅在 ExoPlayerWrapper 初始化期间被调用一次。如果您的 Activity 没有重新启动，那么 ExoPlayerWrapper 的实例将与已释放的播放器保持一致。

要么在每次播放视频时创建一个新的 ExoPlayerWrapper 实例，要么在 ExoPlayerWrapper 中创建一个播放器初始化方法，您可以在播放视频之前调用它.