您是否已在项目中创建AppRouter类以满足导航需求？如果尚未创建，建议您按以下方式创建：

import 'package:flutter/material.dart';

import 'screens/home_screen.dart';
import 'screens/login_screen.dart';
import 'screens/settings_screen.dart';

class AppRouter {
  static Route<dynamic> generateRoute(RouteSettings settings) {
    switch (settings.name) {
      case '/':
        return MaterialPageRoute(builder: (_) => HomeScreen());
      case '/login':
        return MaterialPageRoute(builder: (_) => LoginScreen());
      case '/settings':
        return MaterialPageRoute(builder: (_) => SettingsScreen());
      default:
        return MaterialPageRoute(builder: (_) {
          return Scaffold(
            body: Center(
              child: Text('No route defined for ${settings.name}'),
            ),
          );
        });
    }
  }
}

要在您的应用中使用此应用路由器类，您可以定义一个MaterialApp，并将onGenerateRoute属性设置为AppRouter.generateRoute，如下所示：

import 'package:flutter/material.dart';

import 'app_router.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'My App',
      onGenerateRoute: AppRouter.generateRoute,
    );
  }
}

当您导航到应用中的某个屏幕时（例如，通过调用Navigator.pushNamed（context，'/login'）），将调用onGenerateRoute方法，并显示相应的屏幕。