Flutter集成FCM运行一段时间后停止接收通知，重启才恢复怎么解决？

问题根因 #

你遇到的运行一段时间后无法收到推送的问题，核心由以下几个原因导致：

1. 后台消息处理函数直接操作UI组件，后台Isolate独立运行时UI相关实例为空，抛出未捕获异常后中断后续推送接收链路
2. 未监听FCM Token刷新事件，Token定期失效后服务端用旧Token推送无法送达
3. 后台Isolate没有单独初始化依赖服务，被系统回收后再次触发推送时直接调用相关方法抛出异常
4. 云函数推送优先级不足，容易被安卓系统后台拦截

修复方案 #

1. 重构后台消息处理逻辑 #

后台消息运行在独立Isolate中，禁止直接操作UI，且需要单独初始化依赖服务：

Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
  // 后台Isolate必须单独初始化依赖
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();

  // 单独初始化本地通知服务
  FlutterLocalNotificationsPlugin localNotifications = FlutterLocalNotificationsPlugin();
  const AndroidInitializationSettings initSettingsAndroid = AndroidInitializationSettings('@drawable/splash');
  const InitializationSettings initSettings = InitializationSettings(android: initSettingsAndroid);
  await localNotifications.initialize(initSettings);

  // 单独创建通知通道
  const AndroidNotificationChannel channel = AndroidNotificationChannel(
    'high_importance_channel',
    'High Importance Notifications',
    'This channel is used for important notifications.',
    importance: Importance.high,
  );
  await localNotifications
      .resolvePlatformSpecificImplementation<AndroidFlutterLocalNotificationsPlugin>()
      ?.createNotificationChannel(channel);
  
  RemoteNotification notification = message.notification;
  if (notification != null) {
    await localNotifications.show(
      notification.hashCode,
      notification.title,
      notification.body,
      NotificationDetails(
        android: AndroidNotificationDetails(
          channel.id,
          channel.name,
          channel.description,
          icon: '@drawable/splash',
          playSound: true
        ),
      )
    );
  }
  // 所有UI跳转逻辑移除，放到通知点击回调中处理
}

2. 添加FCM Token同步逻辑 #

FCM Token会定期更新，必须监听刷新事件同步到服务端，在_MyAppState的initState中添加如下代码：

// 应用启动时获取当前Token上传
String? initialToken = await FirebaseMessaging.instance.getToken();
if (initialToken != null) {
  FirebaseFirestore.instance
    .collection('users')
    .doc('123456') // 替换为当前登录用户的真实ID
    .collection('tokens')
    .doc(initialToken)
    .set({});
}

// 监听Token刷新事件，自动上传新Token
FirebaseMessaging.instance.onTokenRefresh.listen((newToken) {
  FirebaseFirestore.instance
    .collection('users')
    .doc('123456')
    .collection('tokens')
    .doc(newToken)
    .set({});
});

3. 补充通知点击跳转逻辑 #

把页面跳转逻辑放到通知点击回调中处理，修改本地通知初始化代码：

var initializationSettingsAndroid  = AndroidInitializationSettings('@drawable/splash');
var initializationSettings = InitializationSettings(android:initializationSettingsAndroid);
flutterLocalNotificationsPlugin.initialize(initializationSettings,
  // 前台通知点击回调
  onDidReceiveNotificationResponse: (response) {
    navigatorKey.currentState?.push(MaterialPageRoute(builder: (_) => OrdersScreen()));
  }
);

// 后台状态下点击通知打开应用的回调
FirebaseMessaging.onMessageOpenedApp.listen((RemoteMessage message) {
  navigatorKey.currentState?.push(MaterialPageRoute(builder: (_) => OrdersScreen()));
});

4. 适配安卓系统限制 #

在android/app/src/main/AndroidManifest.xml中添加推送相关权限，降低后台被拦截概率：

<uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="com.google.android.c2dm.permission.RECEIVE" />

可在应用设置中引导用户开启自启动权限、关闭电池优化，进一步提升后台送达率。

5. 优化云函数推送配置 #

调高推送优先级，避免被系统拦截：

await admin.messaging().sendToDevice(tokens,{ 
  notification: {
    title: 'You have new order!',
    body: `Order #  ${original.uniqueOrderNumber}`,
    click_action: 'FLUTTER_NOTIFICATION_CLICK'
  }
}, {
  priority: 'high',
  contentAvailable: true,
});

内容的提问来源于stack exchange，提问作者mcfred