根据一个完整项目学习Flutter—2、顶部导航栏AppBar

Tabbed AppBar

Tabbed AppBar

An AppBar with a TabBar as its bottom widget.(一个AppBar，其TabBar作为底部小部件。)

效果图

A TabBar can be used to navigate among the pages displayed in a TabBarView. Although a TabBar is an ordinary widget that can appear anywhere, it’s most often included in the application’s AppBar.
(TabBar可用于在TabBarView中显示的页面之间导航。虽然TabBar是一个可以出现在任何地方的普通小部件，但它通常包含在应用程序的AppBar中。)

通过创建一个新项目flutter create并lib/main.dart使用以下代码替换内容来尝试此应用程序。

import 'package:flutter/material.dart';

class TabbedAppBarSample extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: DefaultTabController(
        length: choices.length,
        child: Scaffold(
          appBar: AppBar(
            title: const Text('Tabbed AppBar'),
            bottom: TabBar(
              isScrollable: true,
              tabs: choices.map((Choice choice) {
                return Tab(
                  text: choice.title,
                  icon: Icon(choice.icon),
                );
              }).toList(),
            ),
          ),
          body: TabBarView(
            children: choices.map((Choice choice) {
              return Padding(
                padding: const EdgeInsets.all(16.0),
                child: ChoiceCard(choice: choice),
              );
            }).toList(),
          ),
        ),
      ),
    );
  }
}

class Choice {
  const Choice({this.title, this.icon});

  final String title;
  final IconData icon;
}

const List<Choice> choices = const <Choice>[
  const Choice(title: 'CAR', icon: Icons.directions_car),
  const Choice(title: 'BICYCLE', icon: Icons.directions_bike),
  const Choice(title: 'BOAT', icon: Icons.directions_boat),
  const Choice(title: 'BUS', icon: Icons.directions_bus),
  const Choice(title: 'TRAIN', icon: Icons.directions_railway),
  const Choice(title: 'WALK', icon: Icons.directions_walk),
];

class ChoiceCard extends StatelessWidget {
  const ChoiceCard({Key key, this.choice}) : super(key: key);

  final Choice choice;

  @override
  Widget build(BuildContext context) {
    final TextStyle textStyle = Theme.of(context).textTheme.display1;
    return Card(
      color: Colors.white,
      child: Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          crossAxisAlignment: CrossAxisAlignment.center,
          children: <Widget>[
            Icon(choice.icon, size: 128.0, color: textStyle.color),
            Text(choice.title, style: textStyle),
          ],
        ),
      ),
    );
  }
}

void main() {
  runApp(TabbedAppBarSample());
}

本项目中效果图：

QQ截图20190112202040.png

实现代码：

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

class _HomePageState extends State<HomePage>
    with SingleTickerProviderStateMixin {
  /*
  TabController _tabController;
  List<StatelessWidget> _homeLists = List(_tabs.length);

  /// List of the TabBar's tabs
  static const List<Tab> _tabs = const <Tab>[
    const Tab(text: '页面1'),
    const Tab(text: '页面2'),
    const Tab(text: '页面3'),
  ];

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

    // Tab controller init
    _tabController = TabController(
      length: _tabs.length,
      vsync: this,
      initialIndex: 1,
    );

    // List array init
    _homeLists = [
      VehicleList(),
      LaunchList(Url.upcomingList),
      LaunchList(Url.launchesList),
    ];
  }

  @override
  void dispose() {
    _tabController.dispose();
    super.dispose();
  }
  */

  @override
  Widget build(BuildContext context) {
    return new DefaultTabController(
        length: 9,
        child: new Scaffold(
          appBar: new AppBar(
            title: const Text(
              '测试!',
              style: TextStyle(fontWeight: FontWeight.bold),
            ),
            centerTitle: true,
            actions: <Widget>[
              IconButton(
                icon: const Icon(Icons.info_outline),
                onPressed: () => Navigator.push(
                  context,
                  MaterialPageRoute(builder: (context) => AboutPage()),
                ),
              ),
            ],
            bottom: new TabBar(
                labelStyle: TextStyle(
                  fontFamily: 'ProductSans',
                  fontWeight: FontWeight.bold,
                ),
                isScrollable: true,
                tabs: [
                  new Tab(
                    text: "关注",
                  ),
                  new Tab(
                    text: "推荐",
                  ),
                  new Tab(
                    text: "热搜",
                  ), new Tab(
                    text: "关注1",
                  ),
                  new Tab(
                    text: "推荐1",
                  ),
                  new Tab(
                    text: "热搜1",
                  ), new Tab(
                    text: "关注2",
                  ),
                  new Tab(
                    text: "推荐2",
                  ),
                  new Tab(
                    text: "热搜2",
                  )
                ]),
          ),
          body: new TabBarView(children: [
            VehicleList(),
            LaunchList(Url.upcomingList),
            LaunchList(Url.launchesList),
            VehicleList(),
            LaunchList(Url.upcomingList),
            LaunchList(Url.launchesList),
            VehicleList(),
            LaunchList(Url.upcomingList),
            LaunchList(Url.launchesList),
          ]),
        ));
  }
    /*
    return Scaffold(
      appBar: AppBar(
        title: const Text(
          '测试!',
          style: TextStyle(fontWeight: FontWeight.bold),
        ),
        centerTitle: true,
        actions: <Widget>[
          IconButton(
            icon: const Icon(Icons.info_outline),
            onPressed: () => Navigator.push(
                  context,
                  MaterialPageRoute(builder: (context) => AboutPage()),
                ),
          ),
        ],
        bottom: TabBar(
          labelStyle: TextStyle(
            fontFamily: 'ProductSans',
            fontWeight: FontWeight.bold,
          ),
          controller: _tabController,
          tabs: _tabs,
        ),
      ),
      body: TabBarView(controller: _tabController, children: _homeLists),
    );
  }
  */
}

参考TabBar class 可以查看 TabBar 详细信息。