使用Flutter Bloc进行Bloc到Bloc的通信不起作用

Question

我正在尝试通过遵循此doc

来使用flutter_bloc实现bloc到bloc的通信

所以我有2个块：AuthBloc和UserBloc。

UserBloc取决于AuthBloc，可以添加事件以响应AuthBloc的状态更改。例如，当用户成功登录后，应用程序应使用UserBloc加载用户数据。

这是我的AuthBloc：

class AuthenticationBloc
    extends Bloc<AuthenticationEvent, AuthenticationState> {
  final UserRepository userRepository;

  AuthenticationBloc({@required this.userRepository});

  @override
  AuthenticationState get initialState => AuthenticationStateInitial();

  @override
  Stream<AuthenticationState> mapEventToState(
    AuthenticationEvent event,
  ) async* {
    if (event is AuthenticationStarted) {
      bool hasLoggedIn = await userRepository.hasToken();
      if (hasLoggedIn) {
        yield AuthenticationSuccessState();
      } else {
        yield AuthenticationFailureState();
      }
    } else if (event is AuthenticationLoggedIn) {
      yield AuthenticationLoadingState();
      await userRepository.persistToken(event.token);
      yield AuthenticationSuccessState();
    } else if (event is AuthenticationLoggedOut) {
      //...
    }
  }
}

这是我的UserBloc：

class UserBloc extends Bloc<UserEvent, UserState> {
  final UserRepository userRepository;
  final AuthenticationBloc authenticationBloc;
  StreamSubscription authBlocSubscription;

  UserBloc(this.userRepository, this.authenticationBloc) {
    authBlocSubscription = authenticationBloc.listen((authState) {
      print('auth state changed');
      if (authState is AuthenticationSuccessState) {
        print('auth state success');
        //mapEventToState(LoadUserEvent());
      }
    });
  }

  @override
  Future<void> close() {
    authBlocSubscription.cancel();
    return super.close();
  }

  @override
  UserState get initialState => UserInitialState();

  @override
  Stream<UserState> mapEventToState(
    UserEvent event,
  ) async* {
    if (event is LoadUserEvent) {
      yield UserLoadingState();
      user = await userRepository.loadUser();
      yield UserLoadedState(user);
    }
  }
}

但是问题在于订阅只调用了一次。因此，它只会打印一次auth state changed，并且永远不会在身份验证状态更改时再次更新