如何删除Flutter中的默认白色闪屏？我根本不想要闪屏

import 'package:flutter/services.dart';

void main() {
  // 隐藏默认的闪屏
  SystemChrome.setPreferredOrientations([DeviceOrientation.portraitUp])
      .then((_) {
    runApp(MyApp());
  });
}

import 'package:flutter/material.dart';

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      // 设置你的应用程序主题、路由等
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('My App'),
      ),
      body: Center(
        child: Text('Hello, World!'),
      ),
    );
  }
}