Flutter -在长时间运行进程之前更新UI的最佳方法是什么

import 'package:flutter/material.dart';

class MyWidget extends StatefulWidget {
  @override
  _MyWidgetState createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  String _data = '';

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text(_data),
            RaisedButton(
              child: Text('更新UI'),
              onPressed: () {
                _updateUI();
              },
            ),
          ],
        ),
      ),
    );
  }

  Future<void> _updateUI() async {
    // 模拟长时间运行的进程
    await Future.delayed(Duration(seconds: 2));

    // 更新UI
    setState(() {
      _data = '更新后的数据';
    });
  }
}

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: MyWidget(),
    );
  }
}