android MediaSession setActive(false)不工作

Question

我使用MediaSession响应耳机媒体按钮，并希望在暂停活动时停止声音。I还希望在活动暂停时使耳机媒体按钮不活动。

从android文档中，它说setActive方法用于，“如果这个会话当前处于活动状态并准备接收命令”。但是它没有起作用，我还可以在活动暂停的时候用头继续音乐。我是否误解了这种方法的作用？

我的代码如下：

@RequiresApi(Build.VERSION_CODES.LOLLIPOP)
class MainActivity : AppCompatActivity() {

private lateinit var mediaSession: MediaSession
private var mediaPlayer: MediaPlayer? = null

public override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)

    setContentView(R.layout.activity_main)

    mediaPlayer = MediaPlayer.create(this, R.raw.lapple)
    mediaPlayer?.isLooping = true
    mediaPlayer?.start()
    // Create a MediaSessionCompat

    mediaSession = MediaSession(this, "test_log").apply {

        // Enable callbacks from MediaButtons and TransportControls
        setFlags(MediaSession.FLAG_HANDLES_MEDIA_BUTTONS or MediaSession.FLAG_HANDLES_TRANSPORT_CONTROLS)

        // Do not let MediaButtons restart the player when the app is not visible
        setMediaButtonReceiver(null)

        // Set an initial PlaybackState with ACTION_PLAY, so media buttons can start the player
        val stateBuilder = PlaybackState.Builder()
            .setActions(PlaybackState.ACTION_PLAY or PlaybackState.ACTION_PAUSE or PlaybackState.ACTION_PLAY_PAUSE)
        setPlaybackState(stateBuilder.build())

        // MySessionCallback has methods that handle callbacks from a media controller
        setCallback(object : MediaSession.Callback() {
            override fun onPlay() {
                Toast.makeText(
                    this@MainActivity,
                    "${this@MainActivity.hashCode()}: onPlay",
                    Toast.LENGTH_SHORT
                ).show()
                mediaPlayer?.start()
            }

            override fun onPause() {
                mediaPlayer?.pause()
                Toast.makeText(
                    this@MainActivity,
                    "${this@MainActivity.hashCode()}: onPause",
                    Toast.LENGTH_SHORT
                ).show()
            }

        })
    }

    mediaSession.isActive = true

    //mediaController = MediaController(this, mediaSession.sessionToken)

}

override fun onPause() {
    super.onPause()
    mediaSession.isActive = false
    mediaPlayer?.pause()
}

override fun onResume() {
    super.onResume()
    mediaSession.isActive = true
    mediaPlayer?.start()
}

override fun onDestroy() {
    mediaPlayer?.release()
    super.onDestroy()
}

fun newActivity(view: View) {
    startActivity(Intent(this, MainActivity::class.java))
}
}

Answer 1

文档说：

如果此会话当前处于活动状态并已准备好接收命令，则设置。如果设置为false，则可能无法发现会话的控制器。必须将会话设置为active，然后会话才能开始接收媒体按钮事件或传输命令。

它并不是说您应该将其设置为false以停止接收命令。我想如果控制器已经被发现了，那么这个值就不再重要了。

因此，根据这些文档，您应该使用release或setCallback(null)。

Answer 2

记录在案:对我来说，setCallback(null)没有工作，因为我错误地在Manifest.xml中添加了两个MEDIA_BUTTON.BroadcastReceiver。这在没有附加Service的背景下以某种方式启动了Activity

 <application>

        <service
            android:name=".service.MyService">

            <intent-filter>
                <action android:name="android.intent.action.MEDIA_BUTTON" />
            </intent-filter>

        </service>

        <!-- this was the stupid receiver. DO NOT DO IT ;-) -->
        <receiver android:name="androidx.media.session.MediaButtonReceiver">
            <intent-filter>
                <action android:name="android.intent.action.MEDIA_BUTTON" />
            </intent-filter>
        </receiver>
    </application>