Flutter异步编程详解，GitHub标星过万

Flutter中的异步编程通常涉及到Future和async/await。以下是一个简单的例子，展示了如何在Flutter中使用异步编程来获取网络数据：

import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
 
void main() => runApp(MyApp());
 
class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: AsyncHomePage(),
    );
  }
}
 
class AsyncHomePage extends StatefulWidget {
  AsyncHomePage({Key key}) : super(key: key);
 
  @override
  _AsyncHomePageState createState() => _AsyncHomePageState();
}
 
class _AsyncHomePageState extends State<AsyncHomePage> {
  String _data = "Loading...";
 
  Future<void> _fetchData() async {
    final response = await http.get(Uri.parse('https://example.com/api'));
    if (response.statusCode == 200) {
      setState(() {
        _data = response.body;
      });
    } else {
      setState(() {
        _data = "Error: ${response.statusCode}";
      });
    }
  }
 
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Async Programming Example"),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(_data),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _fetchData,
        tooltip: 'Fetch Data',
        child: Icon(Icons.update),
      ),
    );
  }
}

在这个例子中，_fetchData方法被标记为async，这意味着它可以使用await关键字等待一个Future完成。当按下FloatingActionButton时，将调用_fetchData方法，它会异步获取数据，并在获取到数据后使用setState更新用户界面。这是在Flutter中实现异步编程的一个常见模式。