我应该如何在我的Flatter应用程序中使用FirebaseAuth.instance.onAuthStateChanged？

在我的Flatter应用程序中，我试图通过使用提供者包中的ChangeNotifier将Firebase用户对象传递给下行小部件。我的第一个想法是在StreamBuilder中这样做：

  Widget _authBuilder(context, Widget body) {
    final authModel = Provider.of<FAAuthModel>(context);


    return StreamBuilder(
      stream: FirebaseAuth.instance.onAuthStateChanged,
      builder: (context, snapshot) {

        authModel.user = snapshot.data;

        return body;
      },
    );
  }

Widget\u authBuilder（上下文，Widget主体）{
最终authModel=Provider.of（上下文）；
返回流生成器(
流：FirebaseAuth.instance.onAuthStateChanged，
生成器：（上下文，快照）{
authModel.user=snapshot.data；
返回体；
},
);
}

唯一的问题是，显然构建器函数在构建body小部件时异步运行，因此状态同时被标记为脏。有没有更智能的方法将FirebaseUser传递到下行小部件树

I/flutter (28504): ══╡ EXCEPTION CAUGHT BY FOUNDATION LIBRARY ╞════════════════════════════════════════════════════════
I/flutter (28504): The following assertion was thrown while dispatching notifications for FAAuthModel:
I/flutter (28504): setState() or markNeedsBuild() called during build.
I/flutter (28504): This _DefaultInheritedProviderScope<FAAuthModel> widget cannot be marked as needing to build because
I/flutter (28504): the framework is already in the process of building widgets.  A widget can be marked as needing to
I/flutter (28504): be built during the build phase only if one of its ancestors is currently building. This exception
I/flutter (28504): is allowed because the framework builds parent widgets before children, which means a dirty
I/flutter (28504): descendant will always be built. Otherwise, the framework might not visit this widget during this
I/flutter (28504): build phase.
I/flutter (28504): The widget on which setState() or markNeedsBuild() was called was:
I/flutter (28504):   _DefaultInheritedProviderScope<FAAuthModel>
I/flutter (28504): The widget which was currently being built when the offending call was made was:
I/flutter (28504):   StreamBuilder<FirebaseUser>
I/flutter (28504): 

I/颤振（28504）：══╡ 基金会例外╞════════════════════════════════════════════════════════
I/flatter（28504）：在为FAAuthModel发送通知时引发了以下断言：
I/flatter（28504）：在生成过程中调用setState（）或markNeedsBuild（）。
I/flatter（28504）：无法将此_DefaultInheritedProviderScope小部件标记为需要生成，因为
I/flatter（28504）：框架已经在构建小部件。小部件可以标记为需要
I/Flatter（28504）：仅当其一个祖先当前正在构建时，才能在构建阶段构建。这个例外
I/flatter（28504）：是允许的，因为框架在子窗口之前构建父窗口小部件，这意味着脏窗口
I/颤振（28504）：将始终构建后代。否则，框架在此期间可能不会访问此小部件
I/颤振（28504）：构建阶段。
I/flatter（28504）：调用setState（）或markNeedsBuild（）的小部件是：
I/颤振（28504）：\u默认继承的ProviderScope
I/flatter（28504）：当发出违规呼叫时，当前正在构建的小部件是：
I/颤振（28504）：StreamBuilder
I/颤振（28504）：

所以这个问题的答案是，您不应该使用StreamBuilder，而应该使用侦听器

  Widget _authBuilder(context, Widget body) {
    Stream<FirebaseUser> stream;
    final authModel = Provider.of<FAAuthModel>(context);

    stream = FirebaseAuth.instance.onAuthStateChanged;

    stream.listen((snapshot) {

      /* We are not logged in */
      if (snapshot == null && authModel.user == null) {
         //Do nothing
      }
      /* We are not logged in, or we are logging out */
      else if (snapshot == null) {
        authModel.user = null;
        /* We are logged in but we just opened our app */
      } else if (authModel.user == null) {
        authModel.user = snapshot;
        /* We are logged in but something happened e.g. the widget tree was rebuilt and we just logged out? */
      } else if (authModel.user.uid != snapshot.uid) {
        authModel.user = snapshot;
      }
    });

    return body;
  }

Widget\u authBuilder（上下文，Widget主体）{
溪流；
最终authModel=Provider.of（上下文）；
stream=FirebaseAuth.instance.onAuthStateChanged；
stream.listen（（快照）{
/*我们没有登录*/
if（snapshot==null&&authModel.user==null）{
//无所事事
}
/*我们没有登录，或者我们正在注销*/
else if（快照==null）{
authModel.user=null；
/*我们已登录，但我们刚刚打开应用程序*/
}else if（authModel.user==null）{
authModel.user=快照；
/*我们已登录，但发生了一些事情，例如，小部件树已重建，而我们刚刚注销*/
}else if（authModel.user.uid！=snapshot.uid）{
authModel.user=快照；
}
});
返回体；
}

使用StreamBuilder和listener有什么区别吗？