我已经实现了这段代码，以显示来自Web网址的json数据列表。 我试图实现一个简单的提要刷新，但是没有任何效果。
Flutter代码很长，但实际上很简单。它具有主要的flutter类，并且是将来从Web加载json数据的一种方法。
我只想实现一个简单的拉动即可刷新。
我在这里想念什么？
为什么不起作用？
import 'package:flutter/material.dart';
import 'dart:async';
import 'package:http/http.dart' as http;
import 'dart:convert';
import 'package:pull_to_refresh/pull_to_refresh.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'XXX',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'XXX'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
final RefreshController _refreshController = RefreshController();
Future<List<User>> _getUsers() async {
var data = await http.get("xxxxxxxxxxxxx");
if (data.statusCode == 200) {
print('Status Code 200: Ok!');
var jsonData = json.decode(data.body);
List<User> users = [];
for (var k in jsonData.keys) {
var u = jsonData[k];
//print(u["pubdate"]);
User user = User(u["id"], u["source"], u["desc"], u["link"], u["title"], u["img"], u["pubdate"]);
users.add(user);
}
print(users.length);
return users;
} else {
throw Exception('Failed to load json');
}
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: SmartRefresher(
controller: _refreshController,
enablePullDown: true,
header: WaterDropHeader(),
onRefresh: () async {
await Future.delayed(Duration(seconds: 1));
_refreshController.refreshCompleted();
},
child: FutureBuilder(
future: _getUsers(),
builder: (BuildContext context, AsyncSnapshot snapshot){
if(snapshot.data == null){
return Container(
child: Center(
child: Text("Loading..."),
),
);
} else {
return ListView.builder(
itemCount: snapshot.data.length,
itemBuilder: (BuildContext context, int id){
return ListTile(
leading: CircleAvatar(
backgroundImage: NetworkImage(
snapshot.data[id].img
),
),
title: Text(snapshot.data[id].title),
subtitle: Column(
children: <Widget>[
Row(
children: [
Text(
snapshot.data[id].source,
overflow: TextOverflow.fade,
maxLines: 1,
softWrap: false,
),
Spacer(),
Text(snapshot.data[id].pubdate),
],
),
],
)
);
},
);
}
},
),
),
);
}
}
class User {
final int id;
final String source;
final String desc;
final String link;
final String title;
final String img;
final String pubdate;
User(this.id, this.source, this.desc, this.link, this.title, this.img, this.pubdate);
}
答案 0 :(得分：1)
您必须使用户进入 onLoading ，如下所示
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: SmartRefresher(
....
onLoading: _getUsers,
.....
)
}
答案 1 :(得分：0)
解决了！
import 'package:flutter/material.dart';
import 'dart:async';
import 'package:http/http.dart' as http;
import 'dart:convert';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'XXXX',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'XXXXXX'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
//Funcao para buscar as noticias
Future<List<User>> _getUsers() async {
var data = await http.get("XXXXX");
if (data.statusCode == 200) {
print('Status Code 200: Ok!');
var jsonData = json.decode(data.body);
List<User> users = [];
for (var k in jsonData.keys) {
var u = jsonData[k];
//print(u["pubdate"]);
User user = User(u["id"], u["source"], u["desc"], u["link"], u["title"], u["img"], u["pubdate"]);
users.add(user);
}
print(users.length);
return users;
} else {
throw Exception('Failed to load json');
}
}
var refreshKey = GlobalKey<RefreshIndicatorState>();
@override
void initState() {
super.initState();
refreshList();
}
Future<Null> refreshList() async {
refreshKey.currentState?.show(atTop: false);
await Future.delayed(Duration(seconds: 2));
setState(() {
_getUsers();
});
return null;
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: RefreshIndicator(
key: refreshKey,
child: FutureBuilder(
future: _getUsers(),
builder: (BuildContext context, AsyncSnapshot snapshot){
if(snapshot.data == null){
return Center(
child: CircularProgressIndicator(),
);
} else {
return ListView.builder(
itemCount: snapshot.data.length,
itemBuilder: (BuildContext context, int id){
return ListTile(
leading: CircleAvatar(
backgroundImage: NetworkImage(
snapshot.data[id].img
),
),
title: Text(snapshot.data[id].title),
subtitle: Column(
children: <Widget>[
Row(
children: [
Text(
snapshot.data[id].source,
overflow: TextOverflow.fade,
maxLines: 1,
softWrap: false,
),
Spacer(),
Text(snapshot.data[id].pubdate),
],
),
],
)
);
},
);
}
},
),
onRefresh: refreshList,
),
);
}
}
class User {
final int id;
final String source;
final String desc;
final String link;
final String title;
final String img;
final String pubdate;
User(this.id, this.source, this.desc, this.link, this.title, this.img, this.pubdate);
}