BottomNavigationBar 示例

main.dart

import 'package:flutter/material.dart';

void main() => runApp((MyApp()));

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: MyHomePage(),
      title: "MaterialApp示例",
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
//  当前选中的索引
  int _selectedIndex = 1;
//  导航栏中按钮选中对应数据
  final _widgetOptions = [
    Text('Index 0: 信息'),
    Text('Index 1: 通讯录'),
    Text('Index 2: 发现'),
  ];
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("BottomNavigationBar 示例"),
      ),
      body: Center(
        child: _widgetOptions[_selectedIndex],
      ),
//      底部按钮集合
      bottomNavigationBar: BottomNavigationBar(
        items: <BottomNavigationBarItem>[
          BottomNavigationBarItem(
            icon: Icon(Icons.message),
            title: Text('信息'),
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.contacts),
            title: Text('通讯录'),
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.account_circle),
            title: Text('发现'),
          ),
        ],
//        当前选中项的索引
        currentIndex: _selectedIndex,
//        选项选中后的颜色
        fixedColor: Colors.deepPurple,
//        选项按下处理
        onTap: _onItemTap,
      ),
    );
  }

//  选项按下处理，设置当前索引值为index值
  void _onItemTap(int index) {
    setState(() {
      _selectedIndex = index;
    });
  }
}