return new MaterialApp(
  home: new Scaffold(
   body: new Center(
    child: _currentPage // 動(dòng)態(tài)的展示我們當(dāng)前的頁(yè)面
   ),
   bottomNavigationBar: bottomNavigationBar, // 底部工具欄
  ),

  theme: new ThemeData(
  primarySwatch: Colors.blue, // 設(shè)置主題顏色
  ),

 );

import 'package:flutter/material.dart';
import 'package:flutter_demo/index/index.dart';   // 導(dǎo)入index.dart

// 這里為入口函數(shù)
void main() => runApp(new MyApp());

class MyApp extends StatelessWidget {
 // This widget is the root of your application.
 @override
 Widget build(BuildContext context) {
 return new MaterialApp(
  title: 'Flutter Demo',
  home: new Index(),  // 指定去加載 Index頁(yè)面。
 );
 }
}

import 'package:flutter/material.dart';

// 創(chuàng)建一個(gè) Icon 展示控件
class NavigationIconView {

 // 創(chuàng)建兩個(gè)屬性，一個(gè)是 用來(lái)展示 icon， 一個(gè)是動(dòng)畫處理
 final BottomNavigationBarItem item;
 final AnimationController controller;

 // 類似于 java 中的構(gòu)造方法
 // 創(chuàng)建 NavigationIconView 需要傳入三個(gè)參數(shù)， icon 圖標(biāo)，title 標(biāo)題， TickerProvider
 NavigationIconView({Widget icon, Widget title, TickerProvider vsync}):
 item = new BottomNavigationBarItem(
  icon: icon,
  title: title,
 ),
 controller = new AnimationController(
  duration: kThemeAnimationDuration, // 設(shè)置動(dòng)畫持續(xù)的時(shí)間
  vsync: vsync       // 默認(rèn)屬性和參數(shù)
 );
}

import 'package:flutter/material.dart';
import 'package:flutter_demo/NoticePage/notice_page.dart';
import 'package:flutter_demo/home/home_page.dart';
import 'package:flutter_demo/idea/idea_page.dart';
import 'package:flutter_demo/market/market_page.dart';
import 'package:flutter_demo/my/my_page.dart';

import 'navigation_icon_view.dart'; // 如果是在同一個(gè)包的路徑下，可以直接使用對(duì)應(yīng)的文件名

// 創(chuàng)建一個(gè) 帶有狀態(tài)的 Widget Index
class Index extends StatefulWidget {

 // 固定的寫法
 @override
 State<StatefulWidget> createState() => new _IndexState();
}

// 要讓主頁(yè)面 Index 支持動(dòng)效，要在它的定義中附加mixin類型的對(duì)象TickerProviderStateMixin
class _IndexState extends State<Index> with TickerProviderStateMixin{

 int _currentIndex = 0; // 當(dāng)前界面的索引值
 List<NavigationIconView> _navigationViews; // 底部圖標(biāo)按鈕區(qū)域
 List<StatefulWidget> _pageList; // 用來(lái)存放我們的圖標(biāo)對(duì)應(yīng)的頁(yè)面
 StatefulWidget _currentPage; // 當(dāng)前的顯示頁(yè)面

 // 定義一個(gè)空的設(shè)置狀態(tài)值的方法
 void _rebuild() {
 setState((){});
 }

 @override
 void initState() {
 super.initState();

 // 初始化導(dǎo)航圖標(biāo)
 _navigationViews = <NavigationIconView>[
  new NavigationIconView(icon: new Icon(Icons.assessment), title: new Text("首頁(yè)"), vsync: this), // vsync 默認(rèn)屬性和參數(shù)
  new NavigationIconView(icon: new Icon(Icons.all_inclusive), title: new Text("想法"), vsync: this),
  new NavigationIconView(icon: new Icon(Icons.add_shopping_cart), title: new Text("市場(chǎng)"), vsync: this),
  new NavigationIconView(icon: new Icon(Icons.add_alert), title: new Text("通知"), vsync: this),
  new NavigationIconView(icon: new Icon(Icons.perm_identity), title: new Text("我的"), vsync: this),
 ];

 // 給每一個(gè)按鈕區(qū)域加上監(jiān)聽
 for (NavigationIconView view in _navigationViews) {
  view.controller.addListener(_rebuild);
 }

 // 將我們 bottomBar 上面的按鈕圖標(biāo)對(duì)應(yīng)的頁(yè)面存放起來(lái)，方便我們?cè)邳c(diǎn)擊的時(shí)候
 _pageList = <StatefulWidget>[
  new HomePage(),
  new IdeaPage(),
  new MarketPage(),
  new NoticePage(),
  new MyPage()
 ];
 _currentPage = _pageList[_currentIndex];
 }

 @override
 Widget build(BuildContext context) {

 // 聲明定義一個(gè) 底部導(dǎo)航的工具欄
 final BottomNavigationBar bottomNavigationBar = new BottomNavigationBar(
  items: _navigationViews
   .map((NavigationIconView navigationIconView) => navigationIconView.item)
   .toList(), // 添加 icon 按鈕
  currentIndex: _currentIndex, // 當(dāng)前點(diǎn)擊的索引值
  type: BottomNavigationBarType.fixed, // 設(shè)置底部導(dǎo)航工具欄的類型：fixed 固定
  onTap: (int index){ // 添加點(diǎn)擊事件
  setState((){ // 點(diǎn)擊之后，需要觸發(fā)的邏輯事件
   _navigationViews[_currentIndex].controller.reverse();
   _currentIndex = index;
   _navigationViews[_currentIndex].controller.forward();
   _currentPage = _pageList[_currentIndex];
  });
  },
 );

 return new MaterialApp(
  home: new Scaffold(
   body: new Center(
    child: _currentPage // 動(dòng)態(tài)的展示我們當(dāng)前的頁(yè)面
   ),
   bottomNavigationBar: bottomNavigationBar, // 底部工具欄
  ),

  theme: new ThemeData(
  primarySwatch: Colors.blue, // 設(shè)置主題顏色
  ),

 );
 }

}

import 'package:flutter/material.dart';

class HomePage extends StatefulWidget{
 @override
 State<StatefulWidget> createState() => new _HomePageState();
}

class _HomePageState extends State<HomePage> {

 @override
 Widget build(BuildContext context) {
 return new MaterialApp(
  home: new Scaffold(
  appBar: new AppBar(
   title: new Text('首頁(yè)'),
   actions: <Widget>[
   new Container()
   ],
  ),
  body: new Center(
   child: null,
  ),
  ),
 );
 }
}

import 'package:flutter/material.dart';

class IdeaPage extends StatefulWidget{
 @override
 State<StatefulWidget> createState() => new _IdeaPageState();
}
class _IdeaPageState extends State<IdeaPage> {

 @override
 Widget build(BuildContext context) {
 return new MaterialApp(
  home: new Scaffold(
  appBar: new AppBar(
   title: new Text('想法'),
   actions: <Widget>[
   new Container()
   ],
  ),
  body: new Center(
   child: null,
  ),
  ),
 );
 }
}

import 'package:flutter/material.dart';
class MarketPage extends StatefulWidget{
 @override
 State<StatefulWidget> createState() => new _MarketPageState();
}
class _MarketPageState extends State<MarketPage> {
 @override
 Widget build(BuildContext context) {
 return new MaterialApp(
  home: new Scaffold(
  appBar: new AppBar(
   title: new Text('市場(chǎng)'),
   // 后面的省略
   // ......
  )
  ),
 );
 }

}