Flutter状态管理Provider示例解析

flutter pub add provider

dependencies:
provider: ^6.0.4

import 'package:provider/provider.dart';

class ProviderData with ChangeNotifier {
  int count = 0;
  void increment() {
    count++;
    notifyListeners();
  }
}

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import './provider/index.dart';
import './page/HomePage.dart';
void main() {
  runApp(MyApp());
}
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return ChangeNotifierProvider(
      create: (_) => CountNotifier(),
      child: MaterialApp(
        debugShowCheckedModeBanner: false,
         home: const Scaffold(
            body: HomePage(),
          ),
      ),
    );
  }
}

import 'package:flutter/material.dart';
import 'package:flutter_provider_example/provider_count_example/count_notifier.dart';
import './provider/provider.dart';
class ProviderExample extends StatefulWidget {
  const ProviderExample({Key? key}) : super(key: key);
  @override
  State<ProviderExample> createState() => _ProviderExampleState();
}
class _ProviderExampleState extends State<ProviderExample> {
  final counter = Provider.of<ProviderData>(context);
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("InheritedWidget"),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: (){
          counter.increment();
        },
        child: const Icon(Icons.add),
      ),
      body: Center(
        child: Text(counter.count.toString(),
          style: const TextStyle(
              color: Colors.red,
              fontSize: 50
          ),
        ),
      ),
    );
  }
}