flutter 底部導航欄 BottomNavigationBar

話不多說，上代碼

import 'package:flutter/material.dart';
import 'package:flutter_zhihu/pages/tabs/homeTab.dart';

class TabsController extends StatefulWidget {
  @override
  _TabsControllerState createState() => _TabsControllerState();
}

class _TabsControllerState extends State<TabsController> {

  int _currentIndex = 0;
  final pages = [HomeTab(),HomeTab(),HomeTab(),HomeTab(),HomeTab()];
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('標題'),
        actions: [
          IconButton(icon: Icon(Icons.search), onPressed: (){
            print('惦記了搜索');
          })
        ],
      ),
      bottomNavigationBar: BottomNavigationBar(
        items: bottomNavItems,//配置底部菜單
        currentIndex: _currentIndex,//當前菜單在第幾個
        onTap: (index){
　　　　　　　　//菜單切換事件
            _changePage(index);
        },
        type: BottomNavigationBarType.fixed,//菜單切換效果
      ),
      body: pages[_currentIndex],//菜單頁面切換
    );
  }

　//定義底部菜單
  final List<BottomNavigationBarItem> bottomNavItems  = [
    BottomNavigationBarItem(
      backgroundColor: Colors.blue,
      icon: Icon(Icons.home),
      label: '首頁',
    ),
    BottomNavigationBarItem(
      backgroundColor: Colors.green,
      icon: Icon(Icons.message),
      label: '視頻',
    ),
    BottomNavigationBarItem(
      backgroundColor: Colors.amber,
      icon: Icon(Icons.shopping_cart),
      label: '會員',
    ),
    BottomNavigationBarItem(
      backgroundColor: Colors.red,
      icon: Icon(Icons.person),
      label: '消息',
    ),
    BottomNavigationBarItem(
      backgroundColor: Colors.red,
      icon: Icon(Icons.person),
      label: '我的',
    ),
  ];

  /*切換頁面*/
  void _changePage(int index) {
    /*如果點擊的導航項不是當前項  切換 */
    if (index != _currentIndex) {
      setState(() {
        _currentIndex = index;
      });
    }
  }
}