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Flutter之TabBarView组件项目实战示例

风雨_83 人气:1

TabBarView

TabBarView 是 Material 组件库中提供了 Tab 布局组件,通常和 TabBar 配合使用。

TabBarView 封装了 PageView,它的构造方法:

 TabBarView({
  Key? key,
  required this.children, // tab 页
  this.controller, // TabController
  this.physics,
  this.dragStartBehavior = DragStartBehavior.start,
}) 

TabController 用于监听和控制 TabBarView 的页面切换,通常和 TabBar 联动。如果没有指定,则会在组件树中向上查找并使用最近的一个 DefaultTabController

TabBar

TabBar 为 TabBarView 的导航标题,如下图所示

TabBar 有很多配置参数,通过这些参数我们可以定义 TabBar 的样式,很多属性都是在配置 indicator 和 label,拿上图来举例,Label 是每个Tab 的文本,indicator 指 “新闻” 下面的白色下划线。

const TabBar({
  Key? key,
  required this.tabs, // 具体的 Tabs,需要我们创建
  this.controller,
  this.isScrollable = false, // 是否可以滑动
  this.padding,
  this.indicatorColor,// 指示器颜色,默认是高度为2的一条下划线
  this.automaticIndicatorColorAdjustment = true,
  this.indicatorWeight = 2.0,// 指示器高度
  this.indicatorPadding = EdgeInsets.zero, //指示器padding
  this.indicator, // 指示器
  this.indicatorSize, // 指示器长度,有两个可选值,一个tab的长度,一个是label长度
  this.labelColor, 
  this.labelStyle,
  this.labelPadding,
  this.unselectedLabelColor,
  this.unselectedLabelStyle,
  this.mouseCursor,
  this.onTap,
  ...
}) 

TabBar 通常位于 AppBar 的底部,它也可以接收一个 TabController ,如果需要和 TabBarView 联动, TabBarTabBarView 使用同一个 TabController 即可,注意,联动时 TabBarTabBarView 的孩子数量需要一致。如果没有指定 controller,则会在组件树中向上查找并使用最近的一个 DefaultTabController 。另外我们需要创建需要的 tab 并通过 tabs 传给 TabBar, tab 可以是任何 Widget,不过Material 组件库中已经实现了一个 Tab 组件,我们一般都会直接使用它:

const Tab({
  Key? key,
  this.text, //文本
  this.icon, // 图标
  this.iconMargin = const EdgeInsets.only(bottom: 10.0),
  this.height,
  this.child, // 自定义 widget
})

注意,textchild 是互斥的,不能同时制定。

全部代码:

import 'package:flutter/material.dart';
/// @Author wywinstonwy
/// @Date 2022/1/18 9:09 上午
/// @Description: 
class MyTabbarView1 extends StatefulWidget {
  const MyTabbarView1({Key? key}) : super(key: key);
  @override
  _MyTabbarView1State createState() => _MyTabbarView1State();
}
class _MyTabbarView1State extends State<MyTabbarView1>with SingleTickerProviderStateMixin {
  List<String> tabs =['头条','新车','导购','小视频','改装赛事'];
  late TabController tabController;
  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    tabController = TabController(length: tabs.length, vsync: this);
  }
  @override
  void dispose() {
    tabController.dispose();
    super.dispose();
  }
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('TabbarView',textAlign: TextAlign.center,),
        bottom:TabBar(
            unselectedLabelColor: Colors.white.withOpacity(0.5),
            labelColor: Colors.white,
            // indicatorSize:TabBarIndicatorSize.label,
            indicator:const UnderlineTabIndicator(),
            controller: tabController,
            tabs: tabs.map((e){
              return Tab(text: e,);
            }).toList()) ,
      ),
      body: Column(
      children: [
        Expanded(
          flex: 1,
          child:  TabBarView(
            controller: tabController,
            children: tabs.map((e){
              return Center(child: Text(e,style: TextStyle(fontSize: 50),),);
            }).toList()),)
      ],),
    );
  }
}

运行效果:

滑动页面时顶部的 Tab 也会跟着动,点击顶部 Tab 时页面也会跟着切换。为了实现 TabBar 和 TabBarView 的联动,我们显式创建了一个 TabController,由于 TabController 又需要一个 TickerProvider (vsync 参数), 我们又混入了 SingleTickerProviderStateMixin;

由于 TabController 中会执行动画,持有一些资源,所以我们在页面销毁时必须得释放资源(dispose)。综上,我们发现创建 TabController 的过程还是比较复杂,实战中,如果需要 TabBar 和 TabBarView 联动,通常会创建一个 DefaultTabController 作为它们共同的父级组件,这样它们在执行时就会从组件树向上查找,都会使用我们指定的这个 DefaultTabController。

我们修改后的实现如下:

class TabViewRoute2 extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    List tabs = ["新闻", "历史", "图片"];
    return DefaultTabController(
      length: tabs.length,
      child: Scaffold(
        appBar: AppBar(
          title: Text("App Name"),
          bottom: TabBar(
            tabs: tabs.map((e) => Tab(text: e)).toList(),
          ),
        ),
        body: TabBarView( //构建
          children: tabs.map((e) {
            return KeepAliveWrapper(
              child: Container(
                alignment: Alignment.center,
                child: Text(e, textScaleFactor: 5),
              ),
            );
          }).toList(),
        ),
      ),
    );
  }
}

可以看到我们无需去手动管理 Controller 的生命周期,也不需要提供 SingleTickerProviderStateMixin,同时也没有其它的状态需要管理,也就不需要用 StatefulWidget 了,这样简单很多。

TabBarView+项目实战

实现导航信息流切换效果并缓存前面数据:

1 构建导航头部搜索框

import 'package:flutter/material.dart';
import 'package:qctt_flutter/constant/colors_definition.dart';
enum SearchBarType { home, normal, homeLight }
class SearchBar extends StatefulWidget {
  final SearchBarType searchBarType;
  final String hint;
  final String defaultText;
  final void Function()? inputBoxClick;
  final void Function()? cancelClick;
  final ValueChanged<String>? onChanged;
  SearchBar(
      {this.searchBarType = SearchBarType.normal,
      this.hint = '搜一搜你感兴趣的内容',
      this.defaultText = '',
      this.inputBoxClick,
      this.cancelClick,
      this.onChanged});
  @override
  _SearchBarState createState() => _SearchBarState();
}
class _SearchBarState extends State<SearchBar> {
  @override
  Widget build(BuildContext context) {
    return Container(
      color: Colors.white,
      height: 74,
      child: searchBarView,
    );
  }
  Widget get searchBarView {
    if (widget.searchBarType == SearchBarType.normal) {
      return _genNormalSearch;
    }
    return _homeSearchBar;
  }
  Widget get _genNormalSearch {
    return Container(
        color: Colors.white,
        padding: EdgeInsets.only(top: 40, left: 20, right: 60, bottom: 5),
        child: Container(
          height: 30,
          decoration: BoxDecoration(
              borderRadius: BorderRadius.circular(6),
              color: Colors.grey.withOpacity(0.5)),
          padding: EdgeInsets.only(left: 5, right: 5),
          child: Row(
            children: [
              const Icon(
                Icons.search,
                color: Colors.grey,
                size: 24,
              ),
              Container(child: _inputBox),
              const Icon(
                Icons.clear,
                color: Colors.grey,
                size: 24,
              )
            ],
          ),
        ),);
  }
  //可编辑输入框
  Widget get _homeSearchBar{
    return  Container(
      padding: EdgeInsets.only(top: 40, left: 20, right: 40, bottom: 5),
      decoration: BoxDecoration(gradient: LinearGradient(
          colors: [mainColor,mainColor.withOpacity(0.2)],
          begin:Alignment.topCenter,
          end: Alignment.bottomCenter
      )),
      child: Container(
        height: 30,
        decoration: BoxDecoration(
            borderRadius: BorderRadius.circular(6),
            color: Colors.grey.withOpacity(0.5)),
        padding: EdgeInsets.only(left: 5, right: 5),
        child: Row(
          children: [
            const Icon(
              Icons.search,
              color: Colors.grey,
              size: 24,
            ),
            Container(child: _inputBox),
          ],
        ),
      ),);
  }
 //构建文本输入框
  Widget get _inputBox {
    return Expanded(
      child: TextField(
        style: const TextStyle(
            fontSize: 18.0, color: Colors.black, fontWeight: FontWeight.w300),
        decoration: InputDecoration(
//                   contentPadding: EdgeInsets.fromLTRB(1, 3, 1, 3),
//                   contentPadding: EdgeInsets.only(bottom: 0),
            contentPadding:
                const EdgeInsets.symmetric(vertical: 0, horizontal: 12),
            border: InputBorder.none,
            hintText: widget.hint,
            hintStyle: TextStyle(fontSize: 15),
            enabledBorder: const OutlineInputBorder(
              // borderSide: BorderSide(color: Color(0xFFDCDFE6)),
              borderSide: BorderSide(color: Colors.transparent),
              borderRadius: BorderRadius.all(Radius.circular(4.0)),
            ),
            focusedBorder: const OutlineInputBorder(
                borderRadius: BorderRadius.all(Radius.circular(8)),
                borderSide: BorderSide(color: Colors.transparent))),
      ),
    );
    ;
  }
}

通常一个应该会出现多出输入框,但是每个地方的输入框样式和按钮功能类型会有一定的区别,可以通过初始化传参的方式进行区分。如上面事例中enum SearchBarType { home, normal, homeLight }枚举每个功能页面出现SearchBar的样式和响应事件。

2 构建导航头部TabBar

//导航tabar 关注 头条 新车 ,,。
_buildTabBar() {
  return TabBar(
      controller: _controller,
      isScrollable: true,//是否可滚动
      labelColor: Colors.black,//文字颜色
      labelPadding: const EdgeInsets.fromLTRB(20, 0, 10, 5),
      //下划线样式设置
      indicator: const UnderlineTabIndicator(
        borderSide: BorderSide(color: Color(0xff2fcfbb), width: 3),
        insets: EdgeInsets.fromLTRB(0, 0, 0, 10),
      ),
      tabs: tabs.map<Tab>((HomeChannelModel model) {
        return Tab(
          text: model.name,
        );
      }).toList());
}

因为Tabbar需要和TabBarView进行联动,需要定义一个TabController进行绑定

3 构建导航底部TabBarView容器

//TabBarView容器 信息流列表
_buildTabBarPageView() {
  return KeepAliveWrapper(child:Expanded(
      flex: 1,
      child: Container(
        color: Colors.grey.withOpacity(0.3),
        child: TabBarView(
          controller: _controller,
          children: _buildItems(),
        ),
      )));
}

4 构建导航底部结构填充

底部内容结构包含轮播图左右切换,信息流上下滚动,下拉刷新,上拉加载更多、刷新组件用到SmartRefresher,轮播图和信息流需要拼接,需要用CustomScrollView

代码如下:

_buildRefreshView() {
  //刷新组件
  return SmartRefresher(
    controller: _refreshController,
    enablePullDown: true,
    enablePullUp: true,
    onLoading: () async {
      page++;
      print('onLoading $page');
      //加载频道数据
      widget.homeChannelModel.termId == 0 ? _getTTHomeNews() : _getHomeNews();
    },
    onRefresh: () async {
      page = 1;
      print('onRefresh $page');
      //加载频道数据
      widget.homeChannelModel.termId == 0 ? _getTTHomeNews() : _getHomeNews();
    },
    //下拉头部UI样式
    header: const WaterDropHeader(
      idleIcon: Icon(
        Icons.car_repair,
        color: Colors.blue,
        size: 30,
      ),
    ),
    //上拉底部UI样式
    footer: CustomFooter(
      builder: (BuildContext context, LoadStatus? mode) {
        Widget body;
        if (mode == LoadStatus.idle) {
          body = const Text("pull up load");
        } else if (mode == LoadStatus.loading) {
          body = const CupertinoActivityIndicator();
        } else if (mode == LoadStatus.failed) {
          body = const Text("Load Failed!Click retry!");
        } else if (mode == LoadStatus.canLoading) {
          body = const Text("release to load more");
        } else {
          body = const Text("No more Data");
        }
        return Container(
          height: 55.0,
          child: Center(child: body),
        );
      },
    ),
    //customScrollview拼接轮播图和信息流。
    child: CustomScrollView(
      slivers: [
        SliverToBoxAdapter(
                child: _buildFutureScroll()
              ),
        SliverList(
          delegate: SliverChildBuilderDelegate((content, index) {
            NewsModel newsModel = newsList[index];
            return _buildChannelItems(newsModel);
          }, childCount: newsList.length),
        )
      ],
    ),
  );
}

5 构建导航底部结构轮播图

轮播图单独封装SwiperView小组件

//首页焦点轮播图数据获取
_buildFutureScroll(){
  return FutureBuilder(
      future: _getHomeFocus(),
      builder: (BuildContext context, AsyncSnapshot&lt;FocusDataModel&gt; snapshot){
        print('轮播图数据加载 ${snapshot.connectionState} 对应数据:${snapshot.data}');
        Container widget;
        switch(snapshot.connectionState){
          case ConnectionState.done:
            if(snapshot.data != null){
              widget = snapshot.data!.focusList!.isNotEmpty?Container(
                height: 200,
                width: MediaQuery.of(context).size.width,
                child: SwiperView(snapshot.data!.focusList!,
                    MediaQuery.of(context).size.width),
              ):Container();
            }else{
              widget = Container();
            }
            break;
          case ConnectionState.waiting:
            widget = Container();
            break;
          case ConnectionState.none:
            widget = Container();
            break;
          default :
            widget = Container();
            break;
        }
        return widget;
      });
}

轮播图组件封装,整体基于第三方flutter_swiper_tv

import "package:flutter/material.dart";
import 'package:flutter_swiper_tv/flutter_swiper.dart';
import 'package:qctt_flutter/http/api.dart';
import 'package:qctt_flutter/models/home_channel.dart';
import 'package:qctt_flutter/models/home_focus_model.dart';
class SwiperView extends StatelessWidget {
  // const SwiperView({Key? key}) : super(key: key);
  final double width;
  final List<FocusItemModel> items;
  const SwiperView(this.items,this.width,{Key? key}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return Swiper(
      itemCount: items.length,
      itemWidth: width,
      containerWidth: width,
      itemBuilder: (BuildContext context,int index){
        FocusItemModel focusItemModel = items[index];
        return Stack(children: [
          Container(child:Image.network(focusItemModel.picUrlList![0],fit: BoxFit.fitWidth,width: width,))
        ],
        );
      },
      pagination: const SwiperPagination(),
      // control: const SwiperControl(),
    );
  }
}

6 构建导航底部结构信息流

信息流比较多,每条信息流样式各一,具体要根据服务端返回的数据进行判定。如本项目不至于22种样式,

  _buildChannelItems(NewsModel model) {
    //0,无图,1单张小图 3、三张小图 4.大图推广 5.小图推广 6.专题(统一大图)
// 8.视频小图,9.视频大图 ,,11.banner广告,12.车展,
// 14、视频直播 15、直播回放 16、微头条无图 17、微头条一图
// 18、微头条二图以上 19分组小视频 20单个小视频 22 文章折叠卡片(关注频道)
    switch (model.style) {
      case '1':
        return GestureDetector(
          child: OnePicArticleView(model),
          onTap: ()=>_jumpToPage(model),
        );
      case '3':
        return GestureDetector(
          child: ThreePicArticleView(model),
          onTap: ()=>_jumpToPage(model),
        );
      case '4':
        return GestureDetector(
          child: AdBigPicView(newsModel: model,),
            onTap: ()=>_jumpToPage(model),) ;
      case '9':
        return GestureDetector(
          child: Container(
          padding: const EdgeInsets.only(left: 10, right: 10),
          child: VideoBigPicView(model),
        ),
        onTap: ()=>_jumpToPage(model),
        );
      case '15':
        return GestureDetector(
          child: Container(
            width: double.infinity,
            padding: const EdgeInsets.only(left: 10, right: 10),
            child: LiveItemView(model),
          ),
          onTap: ()=>_jumpToPage(model),
        );
      case '16'://16、微头条无图
        return GestureDetector(
          child: Container(
            width: double.infinity,
            padding: const EdgeInsets.only(left: 10, right: 10),
            child: WTTImageView(model),
          ),
          onTap: ()=>_jumpToPage(model),
        );
      case '17'://17、微头条一图
        return GestureDetector(
          child: Container(
            width: double.infinity,
            padding: const EdgeInsets.only(left: 10, right: 10),
            child: WTTImageView(model),
          ),
          onTap:()=> _jumpToPage(model),
        );
      case '18'://18、微头条二图以上
        //18、微头条二图以上
        return GestureDetector(
          child: Container(
            width: double.infinity,
            padding: const EdgeInsets.only(left: 10, right: 10),
            child: WTTImageView(model),
          ),
          onTap: ()=>_jumpToPage(model),
        );
      case '19': //19分组小视频
        return Container(
          width: double.infinity,
          padding: const EdgeInsets.only(left: 10, right: 10),
          child: SmallVideoGroupView(model.videoList),
        );
      case '20':
      //20小视频 左上方带有蓝色小视频标记
        return Container(
          padding: const EdgeInsets.only(left: 10, right: 10),
          child: VideoBigPicView(model),
        );
      default:
        return Container(
          height: 20,
          color: Colors.blue,
        );
    }
  }

每种样式需要单独封装Cell组件视图。

通过_buildChannelItems(NewsModel model)方法返回的是单独的Cell视图,需要提交给对应的list进行组装:

SliverList(
  delegate: SliverChildBuilderDelegate((content, index) {
    NewsModel newsModel = newsList[index];
    return _buildChannelItems(newsModel);
  }, childCount: newsList.length),
)

这样整个App首页的大体结构就完成了,包含App顶部搜索,基于Tabbar的头部频道导航。TabbarView头部导航联动。CustomScrollView对轮播图信息流进行拼接,等。网络数据是基于Dio进行了简单封装,具体不在这里细说。具体接口涉及隐私,不展示。

至于底部BottomNavigationBar会在后续组件介绍的时候详细介绍到。

总结

本章主要介绍了TabBarView的基本用法以及实际复杂项目中TabBarView的组合使用场景,更多关于Flutter TabBarView组件的资料请关注其它相关文章!

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