在Flutter中，当将整个应用程序包装在WillPopScope中时，不会调用onWillPop

import 'package:flutter/material.dart';

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> with WidgetsBindingObserver {
  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    super.dispose();
  }

  @override
  void didPopRoute() {
    // 处理应用程序的退出操作
    // 在这里执行一些自定义操作，例如显示一个确认对话框
    showDialog(
      context: context,
      builder: (context) => AlertDialog(
        title: Text('确认退出'),
        content: Text('确定要退出应用程序吗？'),
        actions: [
          FlatButton(
            child: Text('取消'),
            onPressed: () => Navigator.of(context).pop(),
          ),
          FlatButton(
            child: Text('确定'),
            onPressed: () => Navigator.of(context).pop(true),
          ),
        ],
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: WillPopScope(
        onWillPop: () async => false,
        child: Scaffold(
          appBar: AppBar(
            title: Text('My App'),
          ),
          body: Center(
            child: Text('Hello, World!'),
          ),
        ),
      ),
    );
  }
}