Flutter底部导航栏的实现方式

import 'package:flutter/material.dart';
import 'bottom_navigation.dart';

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

class MyApp extends StatelessWidget {
 @override
 Widget build(BuildContext context) {
  return MaterialApp(
   title: 'Flutter Demo',
   theme: ThemeData.light(),
   home: BottomNavigationWidget(),
  );
 }
}

import 'package:flutter/material.dart';

class HomePage extends StatelessWidget {
 @override
 Widget build(BuildContext context) {
  return Scaffold(
   appBar: AppBar(title: Text('HomePage'),),
   body: Center(
    child: Text('这是首页'),
   ),
  );
 }
}

import 'package:flutter/material.dart';

class ConstantPage extends StatelessWidget {
 @override
 Widget build(BuildContext context) {
  return Scaffold(
   appBar: AppBar(title: Text('ConstantPage'),),
   body: Center(
    child: Text('这是联系人'),
   ),
  );
 }
}

import 'package:flutter/material.dart';

class FindPage extends StatelessWidget {
 @override
 Widget build(BuildContext context) {
  return Scaffold(
   appBar: AppBar(title: Text('FindPage'),),
   body: Center(
    child: Text('这是发现'),
   ),
  );
 }
}

import 'package:flutter/material.dart';

class MyPage extends StatelessWidget {
 @override
 Widget build(BuildContext context) {
  return Scaffold(
   appBar: AppBar(title: Text('MyPage'),),
   body: Center(
    child: Text('这是我的'),
   ),
  );
 }
}

import 'package:flutter/material.dart';
import 'pages/home_page.dart';
import 'pages/constant_page.dart';
import 'pages/find_page.dart';
import 'pages/my_page.dart';

class BottomNavigationWidget extends StatefulWidget {

 @override
 _BottomNavigationWidgetState createState() => new _BottomNavigationWidgetState();
}

class _BottomNavigationWidgetState extends State<BottomNavigationWidget> {
 final List<Widget> list = List();
 int _currentIndex = 0;
 @override
 void initState() {
  list
   ..add(HomePage())
   ..add(ConstantPage())
   ..add(FindPage())
   ..add(MyPage());
  super.initState();
 }

 @override
 Widget build(BuildContext context) {
  return Scaffold(
   body: list[_currentIndex],
   bottomNavigationBar: BottomNavigationBar(
    currentIndex: _currentIndex,
     onTap: (int index){
      setState(() {
       _currentIndex = index;
      });
     },
     type: BottomNavigationBarType.fixed,
     items: [
      BottomNavigationBarItem(
       icon: Icon(Icons.home,color: Colors.blue,),
       title: Text('首页',style: TextStyle(color: Colors.blue))
      ),
      BottomNavigationBarItem(
        icon: Icon(Icons.contacts,color: Colors.blue,),
        title: Text('联系',style: TextStyle(color: Colors.blue))
      ),
      BottomNavigationBarItem(
        icon: Icon(Icons.find_in_page,color: Colors.blue,),
        title: Text('发现',style: TextStyle(color: Colors.blue))
      ),
      BottomNavigationBarItem(
        icon: Icon(Icons.menu,color: Colors.blue,),
        title: Text('我的',style: TextStyle(color: Colors.blue))
      ),

     ]
   ),
  );
 }
}