问Flutter:没有上下文问题的后台任务的通知导航

EN

final NotificationAppLaunchDetails? notificationAppLaunchDetails =
      await flutterLocalNotificationsPlugin.getNotificationAppLaunchDetails();
  String initialRoute = HomePage.routeName;
  if (notificationAppLaunchDetails?.didNotificationLaunchApp ?? false) {
    selectedNotificationPayload = notificationAppLaunchDetails!.payload;
    initialRoute = SecondPage.routeName;
  }

void main() {

  WidgetsFlutterBinding.ensureInitialized();
  Workmanager().initialize(callbackDispatcher, isInDebugMode: true);
  Workmanager().registerPeriodicTask("1", "test",frequency: Duration(minutes: 15));
  runApp(MyApp());
}

class MyApp extends StatefulWidget {
  @override
  State createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  // This widget is the root of your application.

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      initialRoute: "/",
      navigatorKey: NavigationService.navigatorKey,
      onGenerateRoute: RouteGenerator.generateRoute
    );
  }
}

class RouteGenerator {
  static Route<dynamic> generateRoute(RouteSettings settings) {
    final args = settings.arguments;

    switch(settings.name) {
      case '/first':
        return MaterialPageRoute(builder: (_) => Page1(title: "First"));
      case '/second':
        return MaterialPageRoute(builder: (_) => Page2(title: "Second"));
      case '/third':
        return MaterialPageRoute(builder: (_) => Page3(title: "Third"));
      case '/fourth':
        return MaterialPageRoute(builder: (_) => Page4(title: "Fourth"));
    }
    return MaterialPageRoute(builder: (_) => Page0(title: "Root!"));
  }
}

class NavigationService {
  static final GlobalKey<NavigatorState> navigatorKey = new GlobalKey<NavigatorState>();

  static Future<dynamic> navigateTo(String routeName) {
    return navigatorKey.currentState!.pushNamed(routeName);
  }
}

class DevHttpOverrides extends HttpOverrides {
  @override
  HttpClient createHttpClient(SecurityContext? context) {
    return super.createHttpClient(context)
      ..badCertificateCallback = (X509Certificate cert, String host, int port) => true;
  }
}

void callbackDispatcher() {
  Workmanager().executeTask((task, inputData) async{
        HttpOverrides.global = new DevHttpOverrides();
        var url = 'https://172.16.0.100/handler.php?page=settings';
        http.Response response = await http.get(Uri.parse(url));
        List<dynamic> list = jsonDecode(response.body);


        SharedPreferences prefs = await SharedPreferences.getInstance();
        var usage = "Beides";
        var checkValue = "temp_out";
        var borderValueString = "14.9";
        var checktype = "Grenzwert überschreiten";

        var borderValueDouble;
        var message = "";
        if(usage != "Nur Home Widgets" && checkValue != "" && borderValueString != "" && checktype != "")
        {
          var value = list[0][checkValue];

          if (double.tryParse(borderValueString) != null && double.tryParse(value) != null)
          {
            borderValueDouble = double.parse(borderValueString);
            value = double.parse(value);
          }

          if (checktype == "Grenzwert unterschreiten")
          {
            if (borderValueDouble is double)
            {
              if (value <= borderValueDouble)
              {
                message = "Grenzwert unterschritten";
              }
            }
          }
          else if (checktype == "Grenzwert überschreiten")
          {
            if (borderValueDouble is double)
            {
              if (value >= borderValueDouble)
              {
                message = "Grenzwert überschritten";
              }
            }
          }
          else if (checktype == "Entspricht Grenzwert")
          {
            if (borderValueDouble == value)
            {
              message = "Grenzwert erreicht";
            }
          }
        }

        if(message != "")
        {
          FlutterLocalNotificationsPlugin flip = new FlutterLocalNotificationsPlugin();
          var android = new AndroidInitializationSettings('@mipmap/ic_launcher');
          var ios = new IOSInitializationSettings();

          var settings = new InitializationSettings(android: android, iOS: ios);
          flip.initialize(settings, onSelectNotification: (String? payload) async {
            await NavigationService.navigatorKey.currentState!.push(MaterialPageRoute(builder: (context) => Page4(title: "Hello")));
      
  });
            


          var androidPlatformChannelSpecifics = new AndroidNotificationDetails(
              '1',
              'weatherstation',
              'Notify when values change',
              importance: Importance.max,
              priority: Priority.high
          );

          var iOSPlatformChannelSpecifics = new IOSNotificationDetails();

          var platformChannelSpecifics = new NotificationDetails(
              android: androidPlatformChannelSpecifics,
              iOS: iOSPlatformChannelSpecifics);

          await flip.show(0, message,
              'App öffnen für weitere Details',
              platformChannelSpecifics, payload: 'Default_Sound'
          );
        }

    return Future.value(true);
  });
}