我希望你已经设置了启动图标，如果是的话，现在你可以使用使用https://pub.dev/packages/application_icon

import 'package:application_icon/application_icon.dart';
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: const Text('Plugin example app'),
        ),
        body: Center(
          // use AppIcon to show your application icon
          child: AppIconImage(),
        ),
      ),
    );
  }
}

或者直接从资源文件夹访问启动器图标