有状态的小部件状态在按下后重建

Question

我有一个奇怪的问题：我有这样的 StatefullWidget

class ActionDetailView extends StatefulWidget {
  static const routeName = '/actionDetails';

  @override
  _ActionDetailViewState createState() {
    print("Create state");
    return _ActionDetailViewState();
  }
}

class _ActionDetailViewState extends State<ActionDetailView>
  with WidgetsBindingObserver {
  ActionDetailBloc _bloc = ActionDetailBloc();

  _ActionDetailViewState() {
    print("ActionDetailViewState constructed");
  }

  @override
  void didChangeDependencies() {
      print("DidChangeDependencicse");
      final String actionUID = ModalRoute.of(context).settings.arguments;
    _bloc.init(actionUID);
    super.didChangeDependencies();
  }

  @override
  Widget build(BuildContext context) {
    return StreamBuilder(...)
  }

我的日志是这样的：

============= Enter to view first time =======
2020-01-08 09:53:36.760 5960-5987/ I/flutter: View action //pushed route from another place in code
2020-01-08 09:53:36.808 5960-5987/ I/flutter: Create state //constructor of State is called
2020-01-08 09:53:36.810 5960-5987/ I/flutter: ActionDetailViewState constructed //confirmation of above
2020-01-08 09:53:36.811 5960-5987/ I/flutter: DidChangeDependencicse
2020-01-08 09:53:36.812 5960-5987/ I/flutter: init actionDetailBloc //bloc init method for fill streams
2020-01-08 09:53:36.864 5960-5987/ I/flutter: LoadingUsers //loading state
2020-01-08 09:53:38.253 5960-5987/ I/flutter: pushing to stream
2020-01-08 09:53:38.276 5960-5987/ I/flutter: ReceivedList //data received
=============== Back pressed ====
2020-01-08 09:53:40.870 5960-5987/ I/flutter: DidChangeDependencicse //suddenly it is rebuilt despite not visible
2020-01-08 09:53:40.870 5960-5987/ I/flutter: init actionDetailBloc
2020-01-08 09:53:40.884 5960-5987/ I/flutter: ReceivedList
2020-01-08 09:53:42.160 5960-5987/ I/flutter: pushing to stream

所以从日志来看，小部件的状态似乎在没有收到任何新路由的情况下被重建，所以它造成了麻烦，因为调用了 dispose() 并且 BLoC 中的所有流都被关闭了。 StreamBuilder returns 脚手架处于两种状态之一，具体取决于流数据和主体多个 Widgets 或 StatelessWidgets。无处调用 setState()。 Navigator 通过 pushRouteNamed() 打开了小部件。

我的问题是：是什么导致了这种奇怪的行为，如何预防？想法是每次通过推送路由创建 Widget 时创建 bloc（它包含上下文数据，所以单例不好）

Answer 1

是的，目前他们正在修复它。这是颤振 issue link

link 中还提到了一种解决方法。

副本：

有状态的小部件状态在按下后重建

Statefull widget state is rebuilt after back pressed

flutter

statefulwidget