在 Flutter 中使用 NavigationRail 和 BottomNavigationBar

在Flutter中，你可以使用NavigationRail和BottomNavigationBar来创建一个带有侧边栏的底部导航栏应用。以下是一个简单的示例代码：

import 'package:flutter/material.dart';
 
void main() => runApp(MyApp());
 
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: HomePage(),
    );
  }
}
 
class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}
 
class _HomePageState extends State<HomePage> {
  int _selectedIndex = 0;
 
  void _onItemTapped(int index) {
    setState(() {
      _selectedIndex = index;
    });
  }
 
  List<Widget> _buildPages() {
    return [
      Icon(Icons.home),
      Icon(Icons.favorite),
      Icon(Icons.shopping_cart),
      Icon(Icons.person),
    ];
  }
 
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: _buildPages().elementAt(_selectedIndex),
      ),
      bottomNavigationBar: BottomNavigationBar(
        items: [
          BottomNavigationBarItem(icon: Icon(Icons.home), title: Text('Home')),
          BottomNavigationBarItem(icon: Icon(Icons.favorite), title: Text('Favorites')),
          BottomNavigationBarItem(icon: Icon(Icons.shopping_cart), title: Text('Cart')),
          BottomNavigationBarItem(icon: Icon(Icons.person), title: Text('Profile')),
        ],
        currentIndex: _selectedIndex,
        selectedItemColor: Colors.amber[800],
        onTap: _onItemTapped,
      ),
      navigationRail: NavigationRail(
        selectedIndex: _selectedIndex,
        onDestinationSelected: _onItemTapped,
        destinations: [
          NavigationRailDestination(icon: Icon(Icons.home), label: Text('Home')),
          NavigationRailDestination(icon: Icon(Icons.favorite), label: Text('Favorites')),
          NavigationRailDestination(icon: Icon(Icons.shopping_cart), label: Text('Cart')),
          NavigationRailDestination(icon: Icon(Icons.person), label: Text('Profile')),
        ],
      ),
    );
  }
}

这段代码创建了一个带有NavigationRail侧边栏和BottomNavigationBar底部导航栏的应用。用户可以点击底部导航栏或侧边栏的项目来切换页面。_buildPages方法返回一个包含所有页面的列表，这样