如何在颤动的两个不同屏幕上使用相同的块？

Posted 2023-02-23

【中文标题】如何在颤动的两个不同屏幕上使用相同的块？

【英文标题】：How can I use the same bloc on two different screens in flutter?

【发布时间】：2020-09-06 05:50:57

【问题描述】：

我正在尝试使用flutter_bloc将同一个pad传递给我一个firebaseuser实例到两个不同的屏幕，主屏幕成功地向我显示了这个问题，当我切换到另一个屏幕时，它一直在等待并且不会从那里去。

UserBloc 类

class UserBloc extends Bloc 
   final _auth_repository = FirebaseAuthApiRespository();

  Stream<FirebaseUser> streamFirebase = FirebaseAuth.instance.onAuthStateChanged;
  Stream<FirebaseUser> get auhtStatus => streamFirebase;

  Future<FirebaseUser> signIn() => _auth_repository.signInFirebase();
  signOut() 
    _auth_repository.signOut();
  

  Future<FirebaseUser> signInFacebook() => _auth_repository.signInFacebook();
  signOutFacebook()
    _auth_repository.signOutFacebook();
  


   final _cloudFirestoreRepository = CloudFireStoreRepository();
    void updateUserData(User user) => _cloudFirestoreRepository.updateUserDataFirestore(user);



  @override
  // TODO: implement initialState
  get initialState => null;

  @override
  Stream mapEventToState(event) 
    // TODO: implement mapEventToState
    return null;
  

ma​​in.dart

void main() 
  WidgetsFlutterBinding.ensureInitialized();
  SystemChrome.setEnabledSystemUIOverlays([]);
  runApp(MyApp());


class MyApp extends StatefulWidget 
  MyApp(Key key) : super(key: key);

  @override
  _MyAppState createState() => _MyAppState();


class _MyAppState extends State<MyApp> 
  ManagmentStorage managmentStorage = ManagmentStorage();
  @override
  void initState() 
    managmentStorage.createStragoe();
    super.initState();
  

  Widget build(BuildContext context) 
    return MultiBlocProvider(
       providers: [
        BlocProvider<CameraBloc>(create: (BuildContext context) => CameraBloc()),
        BlocProvider<UserBloc>(create: (BuildContext context) => UserBloc()),
      ],
      child: MaterialApp(
        darkTheme: ThemeData.dark(),
        themeMode: ThemeMode.dark,
        debugShowCheckedModeBanner: false,
        home: SignInScreen(), //ProfileUserHome(), //
        routes: <String, WidgetBuilder>
          '/adddocument': (BuildContext context) => ScreenAddPhoto(),
          '/screenimagedetail': (BuildContext context) => ScreenImageDetail()
        ,
      ),

    );
  

屏幕 1：

class ProfileUser extends StatelessWidget 
  UserBloc userBloc;

  @override
  Widget build(BuildContext context) 
    userBloc = BlocProvider.of<UserBloc>(context);

    return StreamBuilder(
      stream: userBloc.auhtStatus,
      builder: (BuildContext context, AsyncSnapshot snapshot) 
        switch (snapshot.connectionState) 
          case ConnectionState.none:
            return Center(
              child: SpinKitSquareCircle(color: Colors.white),
            );
            break;

          case ConnectionState.waiting:
            return Center(
              child: SpinKitSquareCircle(color: Colors.white),
            );
            break;

          case ConnectionState.active:
            return showPofileData(snapshot);
            break;

          case ConnectionState.done:
            return showPofileData(snapshot);
            break;

          default:
        
      ,
    );
  
  Widget showPofileData(AsyncSnapshot snapshot) 
    if (!snapshot.hasData || snapshot.hasError) 
      return Stack(
        children: <Widget>[
          ListView(
            children: <Widget>[Text("Usuario no logeado. Haz login")],
          ),
        ],
      );
     else 
      var user = User(
        uid: snapshot.data.uid,
        name: snapshot.data.displayName,
        email: snapshot.data.email,
        photoURL: snapshot.data.photoUrl,
      );

      return Stack(
        children: <Widget>[
          UserBody(),
          Header(
            user: user,
          )
        ],
      );
    
  

screen2：

class ProfileUserHome extends StatelessWidget 
  UserBloc userBloc;

  @override
  Widget build(BuildContext context) 
    userBloc = BlocProvider.of<UserBloc>(context);
    return Scaffold(
      body: StreamBuilder(
        stream: userBloc.auhtStatus,
        builder: (BuildContext context, AsyncSnapshot snapshot) 
          switch (snapshot.connectionState) 
            case ConnectionState.none:
              return Center(
                child: SpinKitSquareCircle(color: Colors.white),
              );
              break;

            case ConnectionState.waiting:
              return Center(
                child: SpinKitSquareCircle(color: Colors.white),
              );
              break;

            case ConnectionState.active:
              return profileuserinfo(snapshot);
              break;

            case ConnectionState.done:
              return profileuserinfo(snapshot);
              break;
            default:
          
        ,
      ),
    );
  

  Widget profileuserinfo(AsyncSnapshot snapshot) 
    if (!snapshot.hasData || snapshot.hasError) 
      return Center(child: Text("Usuario no logeado. Haz login"));
     else 
      var user = User(
        uid: snapshot.data.uid,
        name: snapshot.data.displayName,
        email: snapshot.data.email,
        photoURL: snapshot.data.photoUrl,
      );
      return ListView(children: <Widget>[
        HeaderProfileUserHome(user: user)
      ]);
    
  

底部导航栏：

class NavBarUser extends StatefulWidget 
  @override
  State<StatefulWidget> createState() 
    // TODO: implement createState
    return _NavBarUser();
  


class _NavBarUser extends State<NavBarUser> 
  int indexTap = 0;
  @override
  Widget build(BuildContext context) 
    PageController controller = PageController(initialPage: 0, keepPage: true);

    void onTapTapped(int index) 
      setState(() 
        indexTap = index;
        controller.animateToPage(index,
            duration: Duration(milliseconds: 200), curve: Curves.ease);
      );
    

    void pageChanged(int index) 
      setState(() 
        indexTap = index;
      );
    

    final pageView = PageView(
      controller: controller,
      onPageChanged: (index) 
        pageChanged(index);
      ,
      children: <Widget>[UserHome(), ProfileUserHome()],
    );

    return MultiBlocProvider(
       providers: [
        BlocProvider<CameraBloc>(create: (BuildContext context) => CameraBloc()),
        BlocProvider<UserBloc>(create: ( BuildContext context) => UserBloc()),

      ],
      child: Scaffold(
        body: pageView,
        bottomNavigationBar: Theme(
          data: Theme.of(context).copyWith(
              canvasColor: Colors.black,
              primaryColor: Color.fromARGB(230, 226, 80, 116)),
          child: BottomNavigationBar(
            onTap: (index) 
              onTapTapped(index);
            ,
            currentIndex: indexTap,
            items: [
              BottomNavigationBarItem(icon: Icon(Icons.home), title: Text("")),
              BottomNavigationBarItem(
                  icon: Icon(Icons.person), title: Text("")),
            ],
          ),
        ),
      ),

    );
  

登录成功的图片：

图像屏幕 1

图像 screen2 配置文件，这是问题所在：c

在我的个人资料屏幕上什么都没有，当我回家时也没有

【参考方案1】：

你做错了，你使用的是flutter_bloc库：

您需要指定事件和状态。 您需要将事件分派给 Bloc 在 mapEventToState 中处理事件

屈服状态

@覆盖 流 mapEventToState(event) // TODO: 实现 mapEventToState 返回空值；

最后，使用 Flutter_bloc 库而不是 StreamBuilder 的 BlocBuilder 小部件收听状态

该库有一个编写良好的文档和教程，您可以查看https://bloclibrary.dev/#/gettingstarted

---

此外，您在 main.dart 和 NavBarUser 小部件中提供了两次 BLOCS。 因此从 NavBarUser 中删除它

MultiBlocProvider(
       providers: [
        BlocProvider<CameraBloc>(create: (BuildContext context) => CameraBloc()),
        BlocProvider<UserBloc>(create: ( BuildContext context) => UserBloc()),

      ],

【讨论】：

我刚刚删除了它，现在它不会加载两个屏幕中的任何一个：c

任何异常抛出？

我刚刚进入调试模式并将其放在我抛出错误的屏幕上，我不知道为什么我的 pad 没有获取数据：c，我只是添加了调试图像跨度>