Ihre Mediensitzungs-Callbacks rufen Methoden in mehreren APIs auf, um den Player zu steuern, den Audiofokus zu verwalten,
und mit dem Mediensitzungs- und Medienbrowserdienst kommunizieren. Das Feld
Die MediaSession-Logik, die auf Callbacks reagiert, muss einheitlich sein. Das Verhalten
des Callbacks darf nicht von der Identität des Aufrufers abhängen.
eine Aktivität in derselben App, in der MediaSession oder eine andere App mit einem
MediaController mit MediaSession verbunden.
In der folgenden Tabelle wird zusammengefasst, wie diese Aufgaben auf Callbacks verteilt sind.
| onPlay() | onPause() | onStop(). | |
| Audiofokus | requestFocus() übergibt OnAudioFocusChangeListener.Rufe zuerst requestFocus() auf. Fahre nur fort, wenn der Fokus aktiviert ist.
|
abandonAudioFocus()
|
|
| Dienst | startService()
|
stopSelf()
|
|
| Mediensitzung | setActive(true)
- Metadaten und Status aktualisieren |
- Metadaten und Status aktualisieren | setActive(false)
- Metadaten und Status aktualisieren |
| Player-Implementierung | Player starten | Player pausieren | Player anhalten |
| Lauter werden | BroadcastReceiver registrieren
|
BroadcastReceiver abmelden
|
|
| Benachrichtigungen | startForeground(notification)
|
stopForeground(false)
|
stopForeground(false)
|
Hier ist ein Beispiel-Framework für den Callback:
private val intentFilter = IntentFilter(ACTION_AUDIO_BECOMING_NOISY)
// Defined elsewhere...
private lateinit var afChangeListener: AudioManager.OnAudioFocusChangeListener
private val myNoisyAudioStreamReceiver = BecomingNoisyReceiver()
private lateinit var myPlayerNotification: MediaStyleNotification
private lateinit var mediaSession: MediaSessionCompat
private lateinit var service: MediaBrowserService
private lateinit var player: SomeKindOfPlayer
private lateinit var audioFocusRequest: AudioFocusRequest
private val callback = object: MediaSessionCompat.Callback() {
override fun onPlay() {
val am = context.getSystemService(Context.AUDIO_SERVICE) as AudioManager
// Request audio focus for playback, this registers the afChangeListener
audioFocusRequest = AudioFocusRequest.Builder(AudioManager.AUDIOFOCUS_GAIN).run {
setOnAudioFocusChangeListener(afChangeListener)
setAudioAttributes(AudioAttributes.Builder().run {
setContentType(AudioAttributes.CONTENT_TYPE_MUSIC)
build()
})
build()
}
val result = am.requestAudioFocus(audioFocusRequest)
if (result == AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {
// Start the service
startService(Intent(context, MediaBrowserService::class.java))
// Set the session active (and update metadata and state)
mediaSession.isActive = true
// start the player (custom call)
player.start()
// Register BECOME_NOISY BroadcastReceiver
registerReceiver(myNoisyAudioStreamReceiver, intentFilter)
// Put the service in the foreground, post notification
service.startForeground(id, myPlayerNotification)
}
}
public override fun onStop() {
val am = context.getSystemService(Context.AUDIO_SERVICE) as AudioManager
// Abandon audio focus
am.abandonAudioFocusRequest(audioFocusRequest)
unregisterReceiver(myNoisyAudioStreamReceiver)
// Stop the service
service.stopSelf()
// Set the session inactive (and update metadata and state)
mediaSession.isActive = false
// stop the player (custom call)
player.stop()
// Take the service out of the foreground
service.stopForeground(false)
}
public override fun onPause() {
val am = context.getSystemService(Context.AUDIO_SERVICE) as AudioManager
// Update metadata and state
// pause the player (custom call)
player.pause()
// unregister BECOME_NOISY BroadcastReceiver
unregisterReceiver(myNoisyAudioStreamReceiver)
// Take the service out of the foreground, retain the notification
service.stopForeground(false)
}
}
private IntentFilter intentFilter = new IntentFilter(AudioManager.ACTION_AUDIO_BECOMING_NOISY);
// Defined elsewhere...
private AudioManager.OnAudioFocusChangeListener afChangeListener;
private BecomingNoisyReceiver myNoisyAudioStreamReceiver = new BecomingNoisyReceiver();
private MediaStyleNotification myPlayerNotification;
private MediaSessionCompat mediaSession;
private MediaBrowserService service;
private SomeKindOfPlayer player;
private AudioFocusRequest audioFocusRequest;
MediaSessionCompat.Callback callback = new
MediaSessionCompat.Callback() {
@Override
public void onPlay() {
AudioManager am = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
// Request audio focus for playback, this registers the afChangeListener
AudioAttributes attrs = new AudioAttributes.Builder()
.setContentType(AudioAttributes.CONTENT_TYPE_MUSIC)
.build();
audioFocusRequest = new AudioFocusRequest.Builder(AudioManager.AUDIOFOCUS_GAIN)
.setOnAudioFocusChangeListener(afChangeListener)
.setAudioAttributes(attrs)
.build();
int result = am.requestAudioFocus(audioFocusRequest);
if (result == AudioManager.AUDIOFOCUS_REQUEST_GRANTED) {
// Start the service
startService(new Intent(context, MediaBrowserService.class));
// Set the session active (and update metadata and state)
mediaSession.setActive(true);
// start the player (custom call)
player.start();
// Register BECOME_NOISY BroadcastReceiver
registerReceiver(myNoisyAudioStreamReceiver, intentFilter);
// Put the service in the foreground, post notification
service.startForeground(id, myPlayerNotification);
}
}
@Override
public void onStop() {
AudioManager am = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
// Abandon audio focus
am.abandonAudioFocusRequest(audioFocusRequest);
unregisterReceiver(myNoisyAudioStreamReceiver);
// Stop the service
service.stopSelf();
// Set the session inactive (and update metadata and state)
mediaSession.setActive(false);
// stop the player (custom call)
player.stop();
// Take the service out of the foreground
service.stopForeground(false);
}
@Override
public void onPause() {
AudioManager am = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
// Update metadata and state
// pause the player (custom call)
player.pause();
// unregister BECOME_NOISY BroadcastReceiver
unregisterReceiver(myNoisyAudioStreamReceiver);
// Take the service out of the foreground, retain the notification
service.stopForeground(false);
}
};