如何在小部件颤动中使用具有可见性的FutureBuilder

import 'package:flutter/material.dart';

class MyWidget extends StatelessWidget {
  Future<String> fetchData() async {
    // 模拟异步操作，例如从网络获取数据
    await Future.delayed(Duration(seconds: 2));
    return 'Hello, World!';
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('FutureBuilder 示例'),
      ),
      body: Center(
        child: FutureBuilder<String>(
          future: fetchData(),
          builder: (BuildContext context, AsyncSnapshot<String> snapshot) {
            if (snapshot.connectionState == ConnectionState.waiting) {
              // 如果Future未完成，显示加载指示器
              return CircularProgressIndicator();
            } else if (snapshot.hasError) {
              // 如果Future发生错误，显示错误消息
              return Text('发生错误: ${snapshot.error}');
            } else {
              // 如果Future已完成，显示数据
              return Text('数据: ${snapshot.data}');
            }
          },
        ),
      ),
    );
  }
}