flutter - Flutter Bloc-按钮未触发状态更改

Question

我有一个带有自己的main.dart，main_bloc.dart和main_event.dart的main_state.dart:

main_event:
- AppStarted
- GoingHome
- GoingTestHome

main_State:
- StateHome
- StateTestHome

main_bloc:
Stream<MainState> mapEventToState(
    MainEvent event,
  ) async* {
    if (event is AppStarted) {
      print('mainbloc: AppStarted');
dispatch(GoingHome());
    }
    if (event is GoingHome) {
      print('mainbloc: GoingHome');
      yield StateHome();
    }
    if (event is TestHome) {
      print('mainbloc: TestHome');
      yield StateTestHome();
    }
...
}

在我的main.dart中:

class _AppState extends State<App> {
  MainBloc _mainBloc;
  @override
  void initState() {
    super.initState();
    _mainBloc = MainBloc();
    _mainBloc.dispatch(AppStarted());/// <-- 1
  }
...

@override
  Widget build(BuildContext context) {
    return BlocProvider(
        builder: (_) => _mainBloc,
        child: MaterialApp(
          title: 'Home',
          theme: ThemeData(
            ...
          ),
          home: BlocListener<MainBloc, MainState>(
              bloc: _mainBloc,
              listener: (context, state) {
                print('state changed: ${state.toString()}');
                if (state is StateHome) {  /// <-- 2
                  print('main: StateHome');
                  _mainBloc.dispatch(TestHome()); /// <-- 2.1
                } else if (state is StateTestHome) {  /// <-- 3
                  print('main: StateTestHome');
                }
              },
              child: SplashPage()),
...

我做一个快速测试:

当应用启动时，调用_mainBloc.dispatch(AppStarted())，它将从dispatch(GoingHome())调用main_bloc。

BlocListener检测到状态更改(“StateHome”)，因此:
print('main: StateHome'); _mainBloc.dispatch(TestHome());

BlocListener再次检测到状态更改('StateTestHome')，因此:
print('main: StateTestHome');

在控制台中，我可以依次看到所有打印消息:

Restarted application in 1,612ms.
I/flutter (15369): mainbloc: AppStarted
I/flutter (15369): mainbloc: GoingHome
I/flutter (15369): state changed: StateHome
I/flutter (15369): main: StateHome
I/flutter (15369): mainbloc: TestHome
I/flutter (15369): state changed: StateTestHome
I/flutter (15369): main: StateTestHome

到目前为止，它以我预期的方式运行。

但是，当我取出代码2.1时，然后添加一个按钮来触发事件:

...
floatingActionButton: FloatingActionButton(
        child: Text('test'),
        onPressed: () {
          _mainBloc.dispatch(TestHome());
        },
      ),
...

我将获得这样的控制台:

Restarted application in 2,738ms.
I/flutter (15369): mainbloc: AppStarted
I/flutter (15369): mainbloc: GoingHome
I/flutter (15369): state changed: StateHome
I/flutter (15369): main: StateHome
I/flutter (15369):
I/flutter (15369): mainbloc: TestHome ///<-- button trigger

我预计:

Restarted application in 2,738ms.
I/flutter (15369): mainbloc: AppStarted
I/flutter (15369): mainbloc: GoingHome
I/flutter (15369): state changed: StateHome
I/flutter (15369): main: StateHome
I/flutter (15369):
I/flutter (15369): mainbloc: TestHome ///<-- button trigger
I/flutter (15369): state changed: StateTestHome ///<-- expectation
I/flutter (15369): main: StateTestHome          ///<-- expectation

似乎按钮交互未yield状态，或者BlocListener没有捕获状态更改事件。

我在这里想念什么？我该如何解决？

Answer 1

Bloc捕获事件，但是您尝试发送连续的相同状态。在yield StateTestHome();上面尝试另一个产量

喜欢

yield StateIgnored(); // *****
yield StateTestHome();

编辑:或您可以只删除等同的抽象。