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我正在使用 flutter_bloc 和 bloc 包来管理状态。

在子页面中，我正在初始化 bloc 并在父页面后处理 bloc 对象。

当我立即返回父页面时，那个时间块抛出错误Unhandled Exception: Bad state: Cannot add new events after calling close，因为在加载的子页面上我正在调用块中的 api。完成 api 后触发状态。那时已经处理了块对象。

[ERROR:flutter/lib/ui/ui_dart_state.cc(148)] Unhandled Exception: Bad state: Cannot add new events after calling close
E/flutter (17290): #0      _BroadcastStreamController.add (dart:async/broadcast_stream_controller.dart:249:24)
E/flutter (17290): #1      Subject._add (package:rxdart/src/subjects/subject.dart:124:16)
E/flutter (17290): #2      Subject.add (package:rxdart/src/subjects/subject.dart:118:5)
E/flutter (17290): #3      Bloc._bindStateSubject.<anonymous closure> (package:bloc/src/bloc.dart:90:23)
E/flutter (17290): #4      Stream.forEach.<anonymous closure>.<anonymous closure> (dart:async/stream.dart:814:45)
E/flutter (17290): #5      _runUserCode (dart:async/stream_pipe.dart:11:23)
E/flutter (17290): #6      Stream.forEach.<anonymous closure> (dart:async/stream.dart:814:11)
E/flutter (17290): #7      _rootRunUnary (dart:async/zone.dart:1132:38)
E/flutter (17290): #8      _CustomZone.runUnary (dart:async/zone.dart:1029:19)
E/flutter (17290): #9      _CustomZone.runUnaryGuarded (dart:async/zone.dart:931:7)
E/flutter (17290): #10     _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:336:11)
E/flutter (17290): #11     _BufferingStreamSubscription._add (dart:async/stream_impl.dart:263:7)
E/flutter (17290): #12     _SyncBroadcastStreamController._sendData (dart:async/broadcast_stream_controller.dart:375:20)
E/flutter (17290): #13     _BroadcastStreamController._add (dart:async/broadcast_stream_controller.dart:287:5)
E/flutter (17290): #14     _rootRunUnary (dart:async/zone.dart:1132:38)
E/flutter (17290): #15     _CustomZone.runUnary (dart:async/zone.dart:1029:19)
E/flutter (17290): #16     _CustomZone.runUnaryGuarded (dart:async/zone.dart:931:7)
E/flutter (17290): #17     _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:336:11)
E/flutter (17290): #18     _BufferingStreamSubscription._add (dart:async/stream_impl.dart:263:7)
E/flutter (17290): #19     _ForwardingStreamSubscription._add (dart:async/stream_pipe.dart:132:11)
E/flutter (17290): #20     _ForwardingStream._handleData (dart:async/stream_pipe.dart:98:10)
E/flutter (17290): #21     _ForwardingStreamSubscription._handleData (dart:async/stream_pipe.dart:164:13)
E/flutter (17290): #22     _rootRunUnary (dart:async/zone.dart:1132:38)
E/flutter (17290): #23     _CustomZone.runUnary (dart:async/zone.dart:1029:19)
E/flutter (17290): #24     _CustomZone.runUnaryGuarded (dart:async/zone.dart:931:7)
E/flutter (17290): #25     _BufferingStreamSubscription._sendData (dart:async/stream_impl.dart:336:11)
E/flutter (17290): #26     _DelayedData.perform (dart:async/stream_impl.dart:591:14)
E/flutter (17290): #27     _StreamImplEvents.handleNext (dart:async/stream_impl.dart:707:11)
E/flutter (17290): #28     _PendingEvents.schedule.<anonymous closure> (dart:async/stream_impl.dart:667:7)
E/flutter (17290): #29     _rootRun (dart:async/zone.dart:1120:38)
E/flutter (17290): #30     _CustomZone.run (dart:async/zone.dart:1021:19)
E/flutter (17290): #31     _CustomZone.runGuarded (dart:async/zone.dart:923:7)
E/flutter (17290): #32     _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:963:23)
E/flutter (17290): #33     _rootRun (dart:async/zone.dart:1124:13)
E/flutter (17290): #34     _CustomZone.run (dart:async/zone.dart:1021:19)
E/flutter (17290): #35     _CustomZone.runGuarded (dart:async/zone.dart:923:7)
E/flutter (17290): #36     _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:963:23)
E/flutter (17290): #37     _microtaskLoop (dart:async/schedule_microtask.dart:41:21)
E/flutter (17290): #38     _startMicrotaskLoop (dart:async/schedule_microtask.dart:50:5)

那么当 bloc 已经处置时如何处理这些？

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1 回答 1

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为父母和孩子使用公共集团。在调用子项时在父项中创建/初始化 bloc，如下所示：

`BlocProvider.value( value: BlocProvider.of<BlocA>(context), child: ScreenA(), );`

通过上面的写法，您将保持 bloc 不被处理，然后您可以简单地访问 child 中的 bloc，如下所示：

BlocProvider.of<BlocA>(context)

只是不要在孩子中处置它，然后，当你从孩子回到父母时，你的集团不会被处置，它只会在父母销毁或处置时处置。

一切都写在自述文件中： https ://pub.dev/packages/flutter_bloc

于 2020-03-26T19:31:13.227 回答