Плеер останавливается при выходе из виджета

Question

У меня есть пример из пакета exoplayer musi c player, и когда я запустил musi c и вышел из виджета, мои musi c остановились, я попытался удалить dispose (), да, musi c играет, но я не могу остановить или приостановить ее, и когда я go вернусь, мой сеанс не сохраняется ... как я могу увидеть мой текущий сеанс (это как длительность, воспроизведение / пауза)? это пример кода:

class PlayerWidget extends StatefulWidget {
  final String url;
  final List<String> urls;

  PlayerWidget({this.url, this.urls});

  @override
  State<StatefulWidget> createState() {
    return _PlayerWidgetState(url, urls);
  }
}

class _PlayerWidgetState extends State<PlayerWidget> {
  String url;
  List<String> urls;

  AudioPlayer _audioPlayer;
  Duration _duration;
  Duration _position;
  int _currentIndex = 0;

  PlayerState _playerState = PlayerState.RELEASED;
  StreamSubscription _durationSubscription;
  StreamSubscription _positionSubscription;
  StreamSubscription _playerCompleteSubscription;
  StreamSubscription _playerErrorSubscription;
  StreamSubscription _playerStateSubscription;
  StreamSubscription _playerIndexSubscription;
  StreamSubscription _playerAudioSessionIdSubscription;
  StreamSubscription _notificationActionCallbackSubscription;

  get _isPlaying => _playerState == PlayerState.PLAYING;
  get _durationText => _duration?.toString()?.split('.')?.first ?? '';
  get _positionText => _position?.toString()?.split('.')?.first ?? '';

  _PlayerWidgetState(this.url, this.urls);

  @override
  void initState() {
    super.initState();
    _initAudioPlayer();
  }

  @override
  void dispose() {
    _audioPlayer.dispose();
    _durationSubscription?.cancel();
    _positionSubscription?.cancel();
    _playerCompleteSubscription?.cancel();
    _playerErrorSubscription?.cancel();
    _playerStateSubscription?.cancel();
    _playerIndexSubscription?.cancel();
    _playerAudioSessionIdSubscription?.cancel();
    _notificationActionCallbackSubscription?.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      children: <Widget>[
        Padding(
          padding: const EdgeInsets.only(),
          child: Row(
            children: <Widget>[
            ],
          ),
        ),
        Padding(
          padding: const EdgeInsets.only(top: 10),
          child: Row(
            mainAxisSize: MainAxisSize.min,
            children: [
              IconButton(
                onPressed: _isPlaying
                    ? () => _pause()
                    : () => _play(),
                iconSize: 45.0,
                icon: _isPlaying
                    ? Icon(Icons.pause)
                    : Icon(Icons.play_arrow),
              ),
            ],
          ),
        ),
        Row(
          mainAxisSize: MainAxisSize.min,
          children: [
            Text(
              _position != null
                  ? '${_positionText ?? ''} / ${_durationText ?? ''}'
                  : _duration != null
                  ? _durationText : '',
              style: TextStyle(fontSize: 20.0),
            ),
          ],
        ),
        SizedBox(
          width: 400,
          child: SliderTheme(
            data: SliderThemeData(
              thumbShape: RoundSliderThumbShape(enabledThumbRadius: 5),
              trackHeight: 3,
              thumbColor: Colors.pink,
              inactiveTrackColor: Colors.grey,
              activeTrackColor: Colors.pink,
              overlayColor: Colors.transparent,
            ),
            child: Slider(
              value:
              _position != null ? _position.inMilliseconds.toDouble() : 0.0,
              min: 0.0,
              max:
              _duration != null ? _duration.inMilliseconds.toDouble() : 0.0,
              onChanged: (double value) async {
                final Result result = await _audioPlayer
                    .seekPosition(Duration(milliseconds: value.toInt()));
                if (result == Result.FAIL) {
                  print(
                      "you tried to call audio conrolling methods on released audio player :(");
                } else if (result == Result.ERROR) {
                  print("something went wrong in seek :(");
                }
                _position = Duration(milliseconds: value.toInt());
              },
            ),
          ),
        ),
        Padding(
          padding: const EdgeInsets.symmetric(vertical: 15),
          child: Container(
            height: 2,
            decoration: BoxDecoration(
              border: Border(
                bottom: BorderSide(
                  color: Colors.black,
                ),
              ),
            ),
          ),
        ),
      ],
    );
  }

  void _initAudioPlayer() {
    _audioPlayer = AudioPlayer();
    _durationSubscription = _audioPlayer.onDurationChanged.listen((duration) {
      setState(() {
        _duration = duration;
      });
    });
    _positionSubscription = _audioPlayer.onAudioPositionChanged.listen((pos) {
      setState(() {
        _position = pos;
      });
    });
    _playerStateSubscription =
        _audioPlayer.onPlayerStateChanged.listen((playerState) {
          setState(() {
            _playerState = playerState;
            print(_playerState);
          });
        });
    _playerIndexSubscription =
        _audioPlayer.onCurrentAudioIndexChanged.listen((index) {
          setState(() {
            _position = Duration(milliseconds: 0);
            _currentIndex = index;
          });
        });
    _playerAudioSessionIdSubscription =
        _audioPlayer.onAudioSessionIdChange.listen((audioSessionId) {
          print("audio Session Id: $audioSessionId");
        });
    _notificationActionCallbackSubscription = _audioPlayer
        .onNotificationActionCallback
        .listen((notificationActionName) {
      //do something
    });
    _playerCompleteSubscription = _audioPlayer.onPlayerCompletion.listen((a) {
      _position = Duration(milliseconds: 0);
    });
  }

  Future<void> _play() async {
    final playPosition = (_position != null &&
        _duration != null &&
        _position.inMilliseconds > 0 &&
        _position.inMilliseconds < _duration.inMilliseconds)
        ? _position
        : null;
    await _audioPlayer.play(
      url,
      position: playPosition,
      respectAudioFocus: false,
      playerMode: PlayerMode.BACKGROUND,
    );
  }

  Future<void> _pause() async {
    final Result result = await _audioPlayer.pause();
    if (result == Result.FAIL) {
      print(
          "you tried to call audio conrolling methods on released audio player :(");
    } else if (result == Result.ERROR) {
      print("something went wrong in pause :(");
    }
  }

}