Flutter -尝试从reducer获取小部件上下文的脚手架

dependencies:
  flutter:
    sdk: flutter
  provider: ^5.0.0

class AppState {
  final int count;

  AppState(this.count);
}

class AppReducer {
  static AppState reducer(AppState state, dynamic action) {
    if (action == 'increment') {
      return AppState(state.count + 1);
    } else if (action == 'decrement') {
      return AppState(state.count - 1);
    }
    return state;
  }
}

void main() {
  runApp(
    ChangeNotifierProvider<AppState>(
      create: (_) => AppState(0),
      child: MyApp(),
    ),
  );
}

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

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

    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter App'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text('Count: ${appState.count}'),
            RaisedButton(
              child: Text('Increment'),
              onPressed: () {
                Provider.of<AppState>(context, listen: false).reducer('increment');
              },
            ),
            RaisedButton(
              child: Text('Decrement'),
              onPressed: () {
                Provider.of<AppState>(context, listen: false).reducer('decrement');
              },
            ),
          ],
        ),
      ),
    );
  }
}