我建议进一步调查继承的小部件。下面的代码显示了如何在异步更新数据时使用它们：
import 'dart:convert';import 'package:flutter/material.dart';import 'package:http/http.dart' as http;void main() { runApp(new MaterialApp( title: 'Inherited Widgets Demo', theme: new ThemeData( primarySwatch: Colors.blue, ), home: new Scaffold( appBar: new AppBar( title: new Text('Inherited Widget Example'), ), body: new NamePage())));}// Inherited widget for managing a nameclass NameInheritedWidget extends InheritedWidget { const NameInheritedWidget({ Key key, this.name, Widget child}) : super(key: key, child: child); final String name; @override bool updateShouldNotify(NameInheritedWidget old) { print('In updateShouldNotify'); return name != old.name; } static NameInheritedWidget of(BuildContext context) { // You could also just directly return the name here // as there's only one field return context.inheritFromWidgetOfExactType(NameInheritedWidget); }}// Stateful widget for managing name dataclass NamePage extends StatefulWidget { @override _NamePageState createState() => new _NamePageState();}// State for managing fetching name data over HTTPclass _NamePageState extends State<NamePage> { String name = 'Placeholder'; // Fetch a name asynchonously over HTTP _get() async { var res = await http.get('https://jsonplaceholder.typipre.com/users'); var name = json.depre(res.body)[0]['name']; setState(() => this.name = name); } @override void initState() { super.initState(); _get(); } @override Widget build(BuildContext context) { return new NameInheritedWidget( name: name, child: const IntermediateWidget() ); }}// Intermediate widget to show how inherited widgets// can propagate changes down the widget treeclass IntermediateWidget extends StatelessWidget { // Using a const constructor makes the widget cacheable const IntermediateWidget(); @override Widget build(BuildContext context) { return new Center( child: new Padding( padding: new EdgeInsets.all(10.0), child: const NameWidget())); }}class NameWidget extends StatelessWidget { const NameWidget(); @override Widget build(BuildContext context) { final inheritedWidget = NameInheritedWidget.of(context); return new Text( inheritedWidget.name, style: Theme.of(context).textTheme.display1, ); }}
