如何通过provider在flutter中使用changeNotifier

dependencies:
  flutter:
    sdk: flutter
  provider: ^5.0.0

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

class MyDataModel extends ChangeNotifier {
  int _count = 0;

  int get count => _count;

  void increment() {
    _count++;
    notifyListeners();
  }
}

void main() {
  runApp(
    ChangeNotifierProvider(
      create: (context) => MyDataModel(),
      child: MyApp(),
    ),
  );
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Provider Example',
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final myDataModel = Provider.of<MyDataModel>(context);

    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter Provider Example'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'Count:',
            ),
            Text(
              '${myDataModel.count}',
              style: Theme.of(context).textTheme.headline4,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          myDataModel.increment();
        },
        child: Icon(Icons.add),
      ),
    );
  }
}