Flutter：状态错误：流已被收听 [英] Flutter : Bad state: Stream has already been listened to

问题描述

    class MyPage extends StatelessWidget {
      @override
      Widget build(BuildContext context) {
        return DefaultTabController(
          length: 2,
          child: new Scaffold(
            appBar: TabBar(
              tabs: [
                Tab(child: Text("MY INFORMATION",style: TextStyle(color: Colors.black54),)),
                Tab(child: Text("WEB CALENDER",style: TextStyle(color: Colors.black54),)),
              ],
            ),
            body:PersonalInformationBlocProvider(
              movieBloc: PersonalInformationBloc(),
              child: TabBarView(
                children: [
                  MyInformation(),
                  new SmallCalendarExample(),
                ],
              ),
            ),
          ),
        );
      }
    }
    
    class MyInformation extends StatelessWidget{
      // TODO: implement build
      var deviceSize;
    
      //Column1
      Widget profileColumn(PersonalInformation snapshot) => Container(
        height: deviceSize.height * 0.24,
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceEvenly,
              children: <Widget>[
                Container(
                  decoration: BoxDecoration(
                    borderRadius:
                    new BorderRadius.all(new Radius.circular(50.0)),
                    border: new Border.all(
                      color: Colors.black,
                      width: 4.0,
                    ),
                  ),
                  child: CircleAvatar(
                    backgroundImage: NetworkImage(
                        "http://www.binaythapa.com.np/img/me.jpg"),
                    foregroundColor: Colors.white,
                    backgroundColor: Colors.white,
                    radius: 40.0,
                  ),
                ),
                ProfileTile(
                  title: snapshot.firstName,
                  subtitle: "Developer",
                ),
                SizedBox(
                  height: 10.0,
                ),
              ],
            )
          ],
        ),
      );
      Widget bodyData(PersonalInformation snapshot) {
        return SingleChildScrollView(
            child: Column(
              children: <Widget>[
                profileColumn(snapshot)
              ],
            ),
        );
      }
    
    
      @override
      Widget build(BuildContext context) {
        final personalInformationBloc = PersonalInformationBlocProvider.of(context);
    
        deviceSize = MediaQuery.of(context).size;
        return StreamBuilder(
            stream: personalInformationBloc.results,
            builder: (context,snapshot){
              if (!snapshot.hasData)
                return Center(
                  child: CircularProgressIndicator(),
                );
              return bodyData(snapshot.data);
            }
        );
      }
    }
   

我正在使用Bloc Pattern进行检索Rest API中的数据（仅从JSON调用整个对象，并且仅解析用户名）。该页面包含两个选项卡MyIformation和SmallCalendar。当应用程序运行时，将正确提取数据，一切正常。当我转到选项卡二并返回到选项卡一时，选项卡一的整个屏幕都变为红色，显示错误：
状态错误：流已经被收听。

I am using Bloc Pattern for retrieving data from Rest API(just called the whole object from JSON and parsed user name only). The Page consists of two tabs MyIformation and SmallCalendar. When the app runs the data are fetched correctly and everything is good. When I go to tab two and return to tab one then the whole screens in tab one goes to red showing error: Bad state: Stream has already been listened to.

推荐答案

问题是由于未将控制器放置在bloc中。

The problem was due to not disposing the controllers in bloc.

  void dispose() {
    monthChangedController.close();
    dayPressedController.close();
    resultController.close();
  }

这篇关于Flutter：状态错误：流已被收听的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！