适用于 Flutter 的状态管理工具很多, 有 Scoped、Redux、Provider 等, 不过本人最熟悉最常用的还是 Redux, 其他的也不作探究了。

    依赖：

    1. dependencies:
    2.   flutter_redux: ^0.5.3

    官方示例：

    1. import 'package:flutter/material.dart';
    2. import 'package:flutter_redux/flutter_redux.dart';
    3. import 'package:redux/redux.dart';
    5. // 枚举 Actions
    6. enum Actions { Increment }
    8. // 创建 reducer
    9. int counterReducer(int state, dynamic action) {
    10.   if (action == Actions.Increment) {
    11.     return state + 1;
    12.   }
    14.   return state;
    15. }
    17. void main() {
    18.   // 创建store
    19.   final store = new Store<int>(counterReducer, initialState: 0);
    21.   // 将store传入根Widget
    22.   runApp(new FlutterReduxApp(
    23.     title: 'Flutter Redux Demo',
    24.     store: store,
    25.   ));
    26. }
    28. class FlutterReduxApp extends StatelessWidget {
    29.   final Store<int> store;
    30.   final String title;
    32.   FlutterReduxApp({Key key, this.store, this.title}) : super(key: key);
    34.   @override
    35.   Widget build(BuildContext context) {
    36.     // 通过 StoreProvider 将之前的 MaterialApp 或 WidgetsApp 包裹住, 并传入store
    37.     return new StoreProvider<int>(
    38.       // 在 StoreConnector 中的 converter 可以使用此 Store
    39.       store: store,
    40.       child: new MaterialApp(
    41.         theme: new ThemeData.dark(),
    42.         title: title,
    43.         home: new Scaffold(
    44.           appBar: new AppBar(
    45.             title: new Text(title),
    46.           ),
    47.           body: new Center(
    48.             child: new Column(
    49.               mainAxisAlignment: MainAxisAlignment.center,
    50.               children: [
    51.                 new Text(
    52.                   'You have pushed the button this many times:',
    53.                 ),
    54.                 // ① 使用StoreConnector连接到数据源, 并通过converter将源数据转换为string
    55.                 new StoreConnector<int, String>(
    56.                   converter: (store) => store.state.toString(),
    57.                   builder: (context, count) {
    58.                     return new Text(
    59.                       count,
    60.                       style: Theme.of(context).textTheme.display1,
    61.                     );
    62.                   },
    63.                 )
    64.               ],
    65.             ),
    66.           ),
    67.           // ② 使用StoreConnector连接到数据源, 并通过converter返回一个回调方法, 传入 builder 的 callback
    68.           floatingActionButton: new StoreConnector<int, VoidCallback>(
    69.             converter: (store) {
    70.               return () => store.dispatch(Actions.Increment);
    71.             },
    72.             builder: (context, callback) {
    73.               return new FloatingActionButton(
    74.                 // callback 实际调用的是converter返回的 `store.dispatch(Actions.Increment)`
    75.                 onPressed: callback,
    76.                 tooltip: 'asdasdasd',
    77.                 child: new Icon(Icons.add),
    78.               );
    79.             },
    80.           ),
    81.         ),
    82.       ),
    83.     );
    84.   }
    85. }

    上面的 Store 是通过 converter 转换过的数据, 其实也可以将 store 直接放出来使用：

    1. // ① 处
    2. new StoreConnector<int, int>(
    3.   converter: (store) => store.state,
    4.   builder: (context, count) {
    5.     return new Text(
    6.       count.toString(),
    7.       style: Theme.of(context).textTheme.display1,
    8.     );
    9.   },
    10. )
    12. // ② 处
    13. floatingActionButton: new StoreConnector<int, Store>(
    14.   converter: (store) => store,
    15.   builder: (context, store) {
    16.     return new FloatingActionButton(
    17.       onPressed: () {
    18.         store.dispatch(Actions.Increment);
    19.       },
    20.       tooltip: 'asdasdasd',
    21.       child: new Icon(Icons.add),
    22.     );
    23.   },
    24. ),