我如何使用Provider为PageView()提供一个块，而不需要在每次切换页面时重新提交子级？

flutter pub add provider

import 'package:flutter/foundation.dart';

class MyAppState extends ChangeNotifier {
  // 这里可以定义您的数据
  // 例如：String _userName = '';
  // 然后为该数据提供getter和setter方法

  // 示例：获取用户名
  String get userName => _userName;

  // 示例：设置用户名
  void setUserName(String name) {
    _userName = name;
    notifyListeners();
  }
}

import 'package:provider/provider.dart';

void main() {
  runApp(
    MultiProvider(
      providers: [
        ChangeNotifierProvider(create: (_) => MyAppState()),
      ],
      child: MyApp(),
    ),
  );
}

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

class MyPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Consumer<MyAppState>(
      builder: (context, appState, _) {
        return Scaffold(
          appBar: AppBar(
            title: Text('My Page'),
          ),
          body: Column(
            children: [
              // 示例：显示用户名
              Text('Username: ${appState.userName}'),

              // 示例：更新用户名按钮
              RaisedButton(
                onPressed: () {
                  appState.setUserName('New Username');
                },
                child: Text('Change Username'),
              ),
            ],
          ),
        );
      },
    );
  }
}