How does Flutter monitor the system message notifications of Android phones

1. Demand background

Once, when a foreign customer used our company's watch, he reported that after the Android phone was connected to the watch, other people's messages could not be received. After a few days of discussion, he finally wrote a demo for the customer.

2. Implementation steps

Plugin and version used: flutter_notification_listener: ^1.3.2.

Note: When listening to message notifications, you must open the message notification permission of the corresponding application, otherwise you will not be able to monitor

1. Initialize the receiving port
2. Set the receiving port name
3. Initialize NotificationsListener
4. get port name
5. Perform logical operations in port monitoring
6. open monitor

3. Code sharing

1. Install flutter_notification_listener

Add the following to the pubspec.yaml file:

dependencies:
  flutter_notification_listener: ^1.3.2

2. Register the service in the android > src > main > AndroidManifest.xml file

<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="android.permission.FOREGROUND_SERVICE" />

<service android:name="im.zoe.labs.flutter_notification_listener.NotificationsHandlerService"
    android:label="Flutter Notifications Handler"
    android:permission="android.permission.BIND_NOTIFICATION_LISTENER_SERVICE">
    <intent-filter>
        <action android:name="android.service.notification.NotificationListenerService" />
    </intent-filter>
</service>

3. Use flutter_notification_listener

class _NotificationPage extends State<NotificationPage> {
  int _firmwareVersion = -1;
  bool started = true;
  bool _loading = false;

  ReceivePort port = ReceivePort();
  bool hasPort = false;

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

  /// 这里一定要是静态方法
  static void _notificationCallback(NotificationEvent evt) {
    SendPort? send = IsolateNameServer.lookupPortByName("_listener_");
    if (send == null) print("can't find the sender");
    send?.send(evt);
  }

  Future<void> initPlatformState() async {
    if (Platform.isAndroid) {
      if (hasPort) {
        IsolateNameServer.removePortNameMapping("_listener_");
      }
      hasPort = IsolateNameServer.registerPortWithName(port.sendPort, "_listener_");
      NotificationsListener.initialize(callbackHandle: _notificationCallback);
      port.listen((message) => onData(message));
      var isR = await NotificationsListener.isRunning;
      setState(() {
        started = isR!;
      });
    }
  }

  void onData(NotificationEvent event) {
    /// 这里进行逻辑操作
    if (_firmwareVersion != -1) {
      widget.blePlugin.sendMessage(
        MessageBean(
          message: event.text.toString(),
          type: BleMessageType.qq,
          versionCode: _firmwareVersion,
          isHs: true,
          isSmallScreen: true,
        ),
      );
    }
  }

  /// 开启监听
  void startListening() async {
    setState(() {
      _loading = true;
    });
    var hasPermission = await NotificationsListener.hasPermission;
    if (!hasPermission!) {
      NotificationsListener.openPermissionSettings();
      return;
    }

    var isR = await NotificationsListener.isRunning;
    if (!isR!) {
      await NotificationsListener.startService(
        foreground: true,
        title: "Listener Running",
        description: "Welcome to having me"
      );
    }
    setState(() {
      started = true;
      _loading = false;
    });
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        home: Scaffold(
            appBar: AppBar(
              title: const Text("Notification"),
            ),
            body: Center(
                child: ListView(children: [
                  Text("firmwareVersion: $_firmwareVersion"),
                  Text("started: $started"),
                  Text("loading: $_loading"),

                  ElevatedButton(onPressed: startListening, child: const Text("start"),),
                  ElevatedButton(
                      child: const Text("queryFirmwareVersion"),
                      onPressed: () async {
                        String firmwareVersion = await widget.blePlugin.queryFirmwareVersion;
                        int index = firmwareVersion.lastIndexOf('-');
                        String subString = firmwareVersion.substring(index);
                        String version = '';
                        subString.replaceAllMapped(RegExp(r'\d'), (Match m) {
                          version += m[0]!;
                          return m[0]!;
                        });
                        setState(() {
                          _firmwareVersion = int.parse(version);
                        });
                      }),
                ]))));
  }
}

4. Reference text

flutter_notification_listener | Flutter Package