如何将来自fcm firebase的推送通知保存到hive db，在flutter的后台

dependencies:
  hive: ^2.0.0
  hive_flutter: ^1.1.0

import 'package:hive/hive.dart';

part 'push_notification.g.dart';

@HiveType(typeId: 0)
class PushNotification extends HiveObject {
  @HiveField(0)
  late String title;

  @HiveField(1)
  late String body;

  @HiveField(2)
  late String imageUrl;
}

flutter packages pub run build_runner build

import 'package:flutter/material.dart';
import 'package:hive/hive.dart';
import 'package:hive_flutter/hive_flutter.dart';

void main() async {
  await Hive.initFlutter();
  Hive.registerAdapter(PushNotificationAdapter());
  await Hive.openBox<PushNotification>('push_notifications');

  runApp(MyApp());
}

import 'package:firebase_messaging/firebase_messaging.dart';
import 'package:hive/hive.dart';

final FirebaseMessaging _firebaseMessaging = FirebaseMessaging.instance;

void configureFirebaseMessaging() {
  _firebaseMessaging.requestPermission();
  _firebaseMessaging.getToken().then((token) {
    print('FCM Token: $token');
  });

  FirebaseMessaging.onMessage.listen((RemoteMessage message) {
    print('Received FCM message: ${message.notification?.title}');

    final pushNotification = PushNotification()
      ..title = message.notification?.title ?? ''
      ..body = message.notification?.body ?? ''
      ..imageUrl = message.notification?.imageUrl ?? '';

    final box = Hive.box<PushNotification>('push_notifications');
    box.add(pushNotification);
  });
}