// counter_view_model.dart
import 'package:flutter/foundation.dart';class CounterViewModel extends ChangeNotifier {
int _count =;// 私有变量禁止外部随意修改
int get count => _count;// 提供只读访问器
void increment { // 公开接口唯一方法修改数据
_count++;notifyListeners;// 主动通知订阅者更新UI
}
void decrement {
if {
_count--;notifyListeners;}
}
}

// counter_provider.dart
import 'package:flutter/material.dart';import 'counter_view_model.dart';class CounterProvider extends InheritedWidget {
final CounterViewModel viewModel;const CounterProvider({
super.key。required this.viewModel,required super.child,});不过，static CounterProvider of { // 快速获取方式
return context.dependOnInheritedWidgetOfExactType!，}
@override bool updateShouldNotify {
// 比较前后值决定是否重建子组件调整性能 return oldWidget.viewModel.count!
= viewModel.count;}
}

// counter_page.dart
import 'package:flutter/material.dart';import 'counter_provider.dart';import 'counter_view_model.dart';class CounterPage extends StatelessWidget {
const CounterPage;@override Widget build {
final counter = CounterProvider.of.viewModel;return Scaffold(
说到body，Center(
child这方面。AnimatedBuilder(
animation: counter,// 指定观察目标 builder: {
return Text;// 根据数据调整更新 },),)。floatingActionButton:
Row,IconButton,]),);}
}