大神链接

• notifier.dart

import 'package:flutter/foundation.dart';

class CounterNotifier with ChangeNotifier {
    int _count = 0;

    // get 方法
    int get count => _count;

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

• main.dart

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

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return ChangeNotifierProvider.value(
      value: CounterNotifier(),
      child: MaterialApp(
        home: ProvidePage(title: "Provider Demo",),
      ),
    );
  }
}

class ProvidePage extends StatelessWidget {
  final String title;
  ProvidePage({this.title});

  @override
  Widget build(BuildContext context) {

    // 获取 CounterNotifier 数据
    final counter = Provider.of<CounterNotifier>(context);

    return Scaffold(
      appBar: AppBar(
        title: Text(this.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text("点击次数:"),
            Text("${counter.count}",style: Theme.of(context).textTheme.display1,),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: (){
          counter.increment();
        },
        tooltip: "增加",
        child: Icon(Icons.add),
      ),
    );
  }
}