Flutter搜索框

1、main.dart

import 'package:flutter/material.dart';
import 'SearchBarDemo.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter搜索框',
      theme: ThemeData.light(),
      home: SearchBarDemo(),
    );
  }
}

2、SearchBarDemo.dart

import 'package:flutter/material.dart';
import 'assets.dart';

class SearchBarDemo extends StatefulWidget {
  @override
  _SearchBarDemoState createState() => _SearchBarDemoState();
}

class _SearchBarDemoState extends State<SearchBarDemo> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('搜索框'),
        //放大镜效果
        actions: <Widget>[
          IconButton(
            icon: Icon(Icons.search),
            onPressed: (){
              showSearch(context: context, delegate: searchBarDelegate());
            },
          )
        ],
      ),

    );
  }
}


class searchBarDelegate extends SearchDelegate<String>{
//重写右侧的图标
  @override
  List<Widget> buildActions(BuildContext context) {
    // TODO: implement buildActions

    return [
      IconButton(
        icon: Icon(Icons.clear),
        //将搜索内容置为空
        onPressed:()=>query = "",
      )
    ];
  }
//重写返回图标
  @override
  Widget buildLeading(BuildContext context){
    return IconButton(
        icon: AnimatedIcon(
            icon: AnimatedIcons.menu_arrow,
            progress: transitionAnimation
        ),
        //关闭上下文，当前页面
        onPressed: ()=>close(context,null)
    );
  }

  //重写搜索结果
  @override
  Widget buildResults(BuildContext context) {
    return Container(
      width: 100.0,
      height: 100.0,
      child: Card(
        color: Colors.redAccent,
        child: Center(
          child: Text(query),
        ),
      ),
    );
  }

@override
  Widget buildSuggestions(BuildContext context){
    final suggestionList = query.isEmpty
        ? recentSuggest
        : searchList.where((input)=> input.startsWith(query)).toList();

    return ListView.builder(
      itemCount: suggestionList.length ,
        itemBuilder: (context,index)=>ListTile(
          title: RichText(text: TextSpan(text: suggestionList[index].substring(0,query.length),
          style:TextStyle(
              color: Colors.black,fontWeight: FontWeight.bold),
            children: [
              TextSpan(
                text: suggestionList[index].substring(query.length),
                style: TextStyle(color: Colors.grey)

              )
            ]
          ),
          ),
        )
    );
  }

}

3、assets.dart

const searchList = [
  "wangcai",
  "xiaoxianrou",
  "dachangtui",
  "nvfengsi"
];

const recentSuggest = [
  "wangcai推荐-1",
  "nvfengsi推荐-2"
];

4、效果预览