Flutter实现顶部导航栏功能

import 'package:flutter/material.dart';
class AppBarDemoPage extends StatelessWidget {
  const AppBarDemoPage({Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return DefaultTabController(
    //导航栏的长度
      length: 4,
      child: Scaffold(
        appBar: AppBar(
          title: Text("AppBarDemoPage"),
          backgroundColor: Colors.red,
          centerTitle: true,
          bottom: TabBar(
            // isScrollable: true, //可滚动
            indicatorColor: Colors.blueGrey, //指示器的颜色
            labelColor: Colors.blueGrey, //选中文字颜色
            unselectedLabelColor: Colors.white, //为选中文字颜色
            // indicatorSize: TabBarIndicatorSize.label, //指示器与文字等宽
            tabs: <Widget>[
              Tab(text: "热门"),
              Tab(text: "推荐"),
              Tab(text: "好友"),
              Tab(text: "动态"),
            ],
          ),
        ),
        body: TabBarView(
          children: <Widget>[
            Container(
              child: Text("hello"),
            ),
            ListView(
              children: <Widget>[
                ListTile(
                  title: Text("第二个tab"),
                )
              ],
            ),
            ListView(
              children: <Widget>[
                ListTile(
                  title: Text("第三个tab"),
                )
              ],
            ),
            ListView(
              children: <Widget>[
                ListTile(
                  title: Text("第四个tab"),
                )
              ],
            ),
          ],
        ),
      ),
    );
  }
}

import 'package:flutter/material.dart';

class CategoryPage extends StatefulWidget {
  CategoryPage({Key key}) : super(key: key);

  @override
  _CategoryPageState createState() => _CategoryPageState();
}

class _CategoryPageState extends State<CategoryPage> {
  @override
  Widget build(BuildContext context) {
    return DefaultTabController(
      length: 4,
      child: Scaffold(
        appBar: AppBar(
          title: Row(
            children: <Widget>[
              Expanded(
                child: TabBar(
                  tabs: <Widget>[
                    Tab(text: "精选"),
                    Tab(text: "电影"),
                    Tab(text: "动漫"),
                    Tab(text: "NBA"),
                  ],
                ),
              )
            ],
          ),
        ),
        body: TabBarView(
          children: <Widget>[
            ListView(
              children: <Widget>[
                ListTile(
                  title: Text("第一个tab"),
                )
              ],
            ),
            ListView(
              children: <Widget>[
                ListTile(
                  title: Text("第二个tab"),
                )
              ],
            ),
            ListView(
              children: <Widget>[
                ListTile(
                  title: Text("第三个tab"),
                )
              ],
            ),
            ListView(
              children: <Widget>[
                ListTile(
                  title: Text("第四个tab"),
                )
              ],
            ),
          ],
        ),
      ),
    );
  }
}

import 'package:flutter/material.dart';

class NavBarPage extends StatefulWidget {
  NavBarPage({Key key}) : super(key: key);

  @override
  _NavBarPageState createState() => _NavBarPageState();
}

class _NavBarPageState extends State<NavBarPage>
    with SingleTickerProviderStateMixin {
  TabController _tabController;
  @override
  void initState() {
    super.initState(); //length为导航栏的个数
    _tabController = new TabController(vsync: this, length: 2);
    _tabController.addListener(() {
      print(_tabController.index);//打印点击的索引
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text("NavBar"),
          bottom: TabBar(
            controller: this._tabController,
            tabs: <Widget>[
              Tab(text: "热销"),
              Tab(text: "推荐"),
            ],
          ),
        ),
        body: TabBarView(
          controller: this._tabController,
          children: <Widget>[
            Center(child: Text("热销")),
            Center(child: Text("推荐"))
          ],
        ));
  }
}