当应用程序在后台颤动时 FCM 自定义声音

Question

当我的 flutter 应用程序收到推送通知时，我正在尝试播放自定义声音。但是，它仅在打开应用程序时有效。我如何确保用户在应用关闭或在后台听到声音。

class PushNotificationService{
  final FirebaseMessaging _firebaseMessaging = FirebaseMessaging();
  Future initialize(context) async{
    _firebaseMessaging.configure(
      onMessage: (Map<String, dynamic> message) async {
        print("onMessage: $message");
        fetchRideInfo(message['data']['orderId'], context);
      },
      onLaunch: (Map<String, dynamic> message) async {
        print("onLaunch: $message");
        fetchRideInfo(message['data']['orderId'], context);
      },
      onResume: (Map<String, dynamic> message) async {
        print("onResume: $message");
        fetchRideInfo(message['data']['orderId'], context);
      },
    );
  }
  Future<String> getToken() async{
    print("fetching token");
    token = await _firebaseMessaging.getToken();
    print('token got as: $token');

  }

  void fetchRideInfo(orderId, context) {
    print("fetching info");
    showDialog(
      barrierDismissible: false,
      context: context,
      builder: (BuildContext context) =>
          CustomProgressDialog(status:'Fetching details',),);
      assetsAudioPlayer.open(
      Audio('sounds/alert.mp3'),
    );
    assetsAudioPlayer.play();
  }




}

通知正文

{
    "notification": {
    "body": "this is a body",
    "title": "this is a title"
     }, 
    "data": {
    "click_action":"FLUTTER_NOTIFICATION_CLICK", 
    "type": "normal",
    "id": "1", 
    "ride_id": "-MKp1WBP8G2kTgJBqwyl",
    "status": "done"},
    "to":"dv9Yq4qHSVubIohoM8niDX:APA91bGJgQkP7Ir867vyo9oT1CeXbWPKP6xMSDUgwu3242W9odgr4vn5qIIgPmY2LQyPNjL8Pwl8GcRY4TbucxVcCBOM0eBZDHnfhh0E0qYvhdWc_0Yd1oBT_Vh1sA0q-haqXQ3KXib5"

     }