Flutter点击FCM通知打开APP后未弹窗的问题排查

当APP处于完全关闭（终止）状态时，点击FCM通知启动APP，消息不会触发前台场景的onMessage回调，而是需要通过FirebaseMessaging.instance.getInitialMessage()获取启动时的消息。你当前的代码仅处理了前台接收消息的逻辑，缺失冷启动场景的消息处理，导致弹窗不出现。

1. 在main.dart中处理冷启动消息 #

初始化Firebase后，检查是否是通过点击FCM通知启动的APP，若存在启动消息，将其传递给后续页面：

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();

  // 获取冷启动时的FCM消息
  RemoteMessage? initialMessage = await FirebaseMessaging.instance.getInitialMessage();
  
  runApp(MyApp(initialNotification: initialMessage));
}

class MyApp extends StatelessWidget {
  final RemoteMessage? initialNotification;

  const MyApp({super.key, this.initialNotification});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: LoadingScreen(initialNotification: initialNotification),
    );
  }
}

2. 在LoadingScreen中传递消息到HomeScreen #

由于页面流程是main→loading→home，需在LoadingScreen完成加载逻辑后，将启动消息传递给HomeScreen：

class LoadingScreen extends StatefulWidget {
  final RemoteMessage? initialNotification;

  const LoadingScreen({super.key, this.initialNotification});

  @override
  State<LoadingScreen> createState() => _LoadingScreenState();
}

class _LoadingScreenState extends State<LoadingScreen> {
  @override
  void initState() {
    super.initState();
    // 模拟加载流程（如登录校验）
    Future.delayed(const Duration(seconds: 2), () {
      Navigator.pushReplacement(
        context,
        MaterialPageRoute(
          builder: (context) => HomeScreen(initialNotification: widget.initialNotification),
        ),
      );
    });
  }

  @override
  Widget build(BuildContext context) {
    return const Scaffold(
      body: Center(child: CircularProgressIndicator()),
    );
  }
}

3. 在HomeScreen中统一处理所有场景的消息 #

修改HomeScreen，同时处理冷启动消息、前台消息、后台点击通知的消息：

class HomeScreen extends StatefulWidget {
  final RemoteMessage? initialNotification;

  const HomeScreen({super.key, this.initialNotification});

  @override
  State<HomeScreen> createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  @override
  void initState() {
    super.initState();
    // 处理冷启动带来的消息
    if (widget.initialNotification != null) {
      _showNotificationDialog(widget.initialNotification!);
    }

    // 处理前台实时接收的消息
    FirebaseMessaging.onMessage.listen((RemoteMessage message) {
      _showNotificationDialog(message);
    });

    // 处理APP在后台时点击通知的情况
    FirebaseMessaging.onMessageOpenedApp.listen((RemoteMessage message) {
      _showNotificationDialog(message);
    });
  }

  void _showNotificationDialog(RemoteMessage message) {
    // 弹窗展示逻辑，示例使用AlertDialog
    showDialog(
      context: context,
      builder: (context) => AlertDialog(
        title: Text(message.notification?.title ?? '通知'),
        content: Text(message.notification?.body ?? ''),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(context),
            child: const Text('关闭'),
          ),
        ],
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return const Scaffold(
      body: Center(child: Text('首页')),
    );
  }
}

4. 检查FCM通知Payload配置 #

确保发送的FCM通知包含click_action: FLUTTER_NOTIFICATION_CLICK（Android端必填），否则点击通知可能无法正确触发回调，示例Payload：

{
  "notification": {
    "title": "测试通知",
    "body": "这是一条测试消息",
    "click_action": "FLUTTER_NOTIFICATION_CLICK"
  },
  "data": {
    "key": "value"
  },
  "to": "目标设备Token"
}

内容的提问来源于stack exchange，提问作者H Amr