futureBuilder中的setState

FutureBuilder(
  future: fetchData(), // fetchData 应该每次都返回一个新的 Future
  builder: (context, snapshot) {
    // 构建 UI
  },
);

FutureBuilder(
  future: fetchData(),
  builder: (context, snapshot) {
    if (snapshot.connectionState == ConnectionState.waiting) {
      return CircularProgressIndicator();
    } else if (snapshot.hasError) {
      return Text('Error: ${snapshot.error}');
    } else if (snapshot.hasData) {
      // 使用 snapshot.data 更新 UI
      return Text('Data: ${snapshot.data}');
    }
    return Container();
  },
);

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: Text('FutureBuilder Example')),
        body: FutureBuilderExample(),
      ),
    );
  }
}

class FutureBuilderExample extends StatefulWidget {
  @override
  _FutureBuilderExampleState createState() => _FutureBuilderExampleState();
}

class _FutureBuilderExampleState extends State<FutureBuilderExample> {
  Future<String> fetchData() async {
    await Future.delayed(Duration(seconds: 2)); // 模拟网络请求延迟
    return 'Data fetched!';
  }

  @override
  Widget build(BuildContext context) {
    return Center(
      child: FutureBuilder<String>(
        future: fetchData(),
        builder: (context, snapshot) {
          if (snapshot.connectionState == ConnectionState.waiting) {
            return CircularProgressIndicator();
          } else if (snapshot.hasError) {
            return Text('Error: ${snapshot.error}');
          } else if (snapshot.hasData) {
            return Text('Result: ${snapshot.data}');
          }
          return Container();
        },
      ),
    );
  }
}