如何在pushReplacementNamed中设置动画

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: HomePage(),
      routes: {
        '/second': (context) => SecondPage(),
      },
    );
  }
}

class HomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Home'),
      ),
      body: Center(
        child: RaisedButton(
          child: Text('Go to Second Page'),
          onPressed: () {
            Navigator.pushReplacementNamed(context, '/second');
          },
        ),
      ),
    );
  }
}

class SecondPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Second Page'),
      ),
      body: Center(
        child: Text('This is the second page'),
      ),
    );
  }
}

class CustomPageRoute<T> extends MaterialPageRoute<T> {
  CustomPageRoute({
    WidgetBuilder builder,
    RouteSettings settings,
  }) : super(builder: builder, settings: settings);

  @override
  Widget buildTransitions(
    BuildContext context,
    Animation<double> animation,
    Animation<double> secondaryAnimation,
    Widget child,
  ) {
    if (settings.name == '/second') {
      // 设置自定义的动画效果
      return FadeTransition(
        opacity: animation,
        child: child,
      );
    } else {
      // 使用默认的动画效果
      return super.buildTransitions(
        context,
        animation,
        secondaryAnimation,
        child,
      );
    }
  }
}

routes: {
  '/second': (context) => SecondPage(),
},
onGenerateRoute: (settings) {
  return CustomPageRoute(builder: (context) {
    // 根据settings.name返回对应的页面
  }, settings: settings);
},