Flutter入门-04 列表

Flutter的listview4种构建方式

1.listview - 这种构建方式是把固定数据变成 item 传给 childen

  Widget build(BuildContext context) {
    // TODO: implement build
    return ListView(
      padding: EdgeInsets.all(20),
       children: <Widget>[
         Text("AA"),
         Text("BB"),
         Text("CC"),
       ],
    );
  }

 

 

2.ListView.builder - 构建一种 item 类型的列表，当然在 itemBuilder 使用 if、slse 也是能支持多类型 item 的，itemCount 是列表数量

class MyApp extends StatelessWidget{
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return MaterialApp(
      home:Scaffold(
        body:ListView.builder(
          padding: EdgeInsets.all(20),
          itemCount: 50,
          itemBuilder: (context, index) {
            return Text("item:${index}");
          },
        )
      )
    );
  }
}  

 

 

 

 3.

ListView.separated - 带分割线的列表， Flutter中把分割线也是看成一个 widget 来处理的，这里新增了 separatorBuilder 来返回分割线 widget，不过分割线的特点是：不包含最后一项，也就是分割线不会出列表的范围。这中设计我很喜欢，把分割线或是分隔符看成列表的 item，可以极大的方便我们设计列表，可玩性灵活性可以大大增加，至少我们可以根据 index 找到前后 item 的类型，然后考虑可以采取不同类型的分隔 item，最典型的应用就是插入广告了，不用对列表有任何修改

class MyApp extends StatelessWidget{
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return MaterialApp(
      home:Scaffold(
        body:ListView.separated(
        padding: EdgeInsets.all(20),
        itemCount: 50,
        itemBuilder: (context, index) {
          return Text("item:${index}");
        },
        separatorBuilder: (context,index){
          return Container(
            height: 1,
            color: Colors.pink,
          );
        },
      )
      )
    );
  }
} 

 

 4.

ListView.custom() - 需要传入一个实现了 SliverChildDelegate 的组件，如 SliverChildListDelegate 和 SliverChildBuilderDelegate。这里我不详细说，因为没必要，SliverChildListDelegate 就是 listview，SliverChildBuilderDelegate 就是 ListView.builder。这个 ListView.custom 用的也比较少。

 

转载于：https://juejin.im/post/5deceb0f518825128306c403#heading-0

 

一、数据准备

新建文件post.dart

class Post{
  const Post({
    this.title,
    this.author,
    this.imageUrl,
  });

  final String title;
  final String author;
  final String imageUrl;
}

final List<Post> posts = [
  Post(
    title: 'butterfly',
    author: 'unknown',
    imageUrl: 'http://p3.qhimg.com/bdm/1000_618_80/t01db65c4075c033b04.jpg'
  ),
  Post(
    title: 'dog',
    author: 'unknown',
    imageUrl: 'http://p1.qhimg.com/bdm/1000_618_80/t0134dbb70e2ab3ec6b.jpg'
  ),
  Post(
    title: 'girl',
    author: 'unknown',
    imageUrl: 'http://p7.qhimg.com/bdm/1000_618_80/t01102cceddc718708a.jpg'
  ),
  Post(
    title: 'comic01',
    author: 'unknown',
    imageUrl: 'http://p9.qhimg.com/bdm/1000_618_80/t012df0e51dfc77a9a0.jpg'
  ),
  Post(
    title: 'comic02',
    author: 'unknown',
    imageUrl: 'http://p7.qhimg.com/bdm/1000_618_80/t0198a92b613430b12d.jpg'
  ),
  Post(
    title: 'comic03',
    author: 'unknown',
    imageUrl: 'http://p0.qhimg.com/bdm/1000_618_80/t015399549677d9dbec.jpg'
  ),Post(
    title: 'comic04',
    author: 'unknown',
    imageUrl: 'http://p6.qhimg.com/bdm/1000_618_80/t013d563a2293e1435f.jpg'
  ),
];

二、自定义Home部件 继承 StatelessWidget

class Home extends StatelessWidget{
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return Scaffold(
      backgroundColor: Colors.green,
      appBar: AppBar(
        title: Text("DING"),
        elevation: 50.0,
      ),
      body: ListView.builder(
        itemCount: posts.length,
        itemBuilder: _listItemBuilder,
      )
    );
  }
}

三、在Home类中自定义私有方法 _listItemBuilder

Widget _listItemBuilder(BuildContext context, int index){
    return Container(
      color: Colors.blue,
      margin: EdgeInsets.all(8.0),
      child: Column(
        children: <Widget>[
          Image.network(posts[index].imageUrl),
          SizedBox(height: 16.0),
          Text(
            posts[index].title,
            style: Theme.of(context).textTheme.title,
          ),
          Text(
            posts[index].author,
            style: Theme.of(context).textTheme.subhead,
          ),
          SizedBox(height: 20.0)
      ],
      ),
    );
  }

完整代码

import 'package:flutter/material.dart';
import 'model/post.dart';

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


class App extends StatelessWidget{
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return MaterialApp(
      home: Home(),
      theme: ThemeData(
        primarySwatch: Colors.green
      ),
    );
  }
}

class Home extends StatelessWidget{
  Widget _listItemBuilder(BuildContext context, int index){
    return Container(
      color: Colors.blue,
      margin: EdgeInsets.all(8.0),
      child: Column(
        children: <Widget>[
          Image.network(posts[index].imageUrl),
          SizedBox(height: 16.0),
          Text(
            posts[index].title,
            style: Theme.of(context).textTheme.title,
          ),
          Text(
            posts[index].author,
            style: Theme.of(context).textTheme.subhead,
          ),
          SizedBox(height: 20.0)
      ],
      ),
    );
  }
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return Scaffold(
      backgroundColor: Colors.green,
      appBar: AppBar(
        title: Text("DING"),
        elevation: 50.0,
      ),
      body: ListView.builder(
        itemCount: posts.length,
        itemBuilder: _listItemBuilder,
      )
    );
  }
}