错误状态：流已经被监听

Question

我处于错误状态：运行下面的代码时，我已经在StreamView中收听了流，我在Tabview中调用我的流可以很好地运行，但是当我在Tab视图中玩耍时，表明我已经侦听了Stream。不明白是怎么回事。

     class DataServiceColi {

     static Future loadJson(String url) async {
     await Future.delayed(Duration(seconds: 5));

    // Await the http get response, then decode t he json-formatted response.
    http.Response response = await http.get(url);
    if (response.statusCode == 200) {
       String content = response.body;
       collectionColi = json.decode(content);
       print('$collectionColi');
       return collectionColi;
     } else {
       print('Request failed with status: ${response.statusCode}.');
    }
    }
   }

       class DataManagerColis{

       final StreamController<int> _counter = StreamController<int>();
       final StreamController<List> streamController = new BehaviorSubject();
       Stream<List> get counterlist => streamController.stream;

       Stream<List> get colistView async*{
            yield await DataServiceColi.loadJson(colis);
       }

      @override
      void dispose() {
      print('Disposed Statistics Bloc');
       streamController.close();
  }

     DataManagerColis(){
        colistView.listen((list) => streamController.add(list));
    }

   }

这是我的UI小部件：

 @override
 Widget build(BuildContext context) {
     return DefaultTabController(
     length: 3,
    child: Scaffold(
    backgroundColor: Color.fromRGBO(58, 66, 86, 1.0),
    appBar: topAppBar,
    body:TabBarView(children:[
      StreamBuilder<List>(
        stream: manager.colistView,
          builder:(BuildContext context, AsyncSnapshot<List<dynamic>> snapshot){
          switch (snapshot.connectionState) {
            case ConnectionState.none: return Text('Select lot');
            case ConnectionState.waiting:return Center(child: CircularProgressIndicator(backgroundColor:Colors.amberAccent,));
            case ConnectionState.active: return Center(child: CircularProgressIndicator(backgroundColor: Colors.cyanAccent,));
            case ConnectionState.done:

              return ListView.builder(
                scrollDirection: Axis.vertical,
                shrinkWrap: true,
                itemCount: snapshot.data?.length ?? 0,
                //separatorBuilder: (context, index) => Divider(),
                itemBuilder: (BuildContext context, int index) {
                  print(index);
                  return Card(
                    elevation: 8.0,
                    margin: new EdgeInsets.symmetric(horizontal: 10.0, vertical: 6.0),
                    child: Container(
                      decoration: BoxDecoration(color: Color.fromRGBO(64, 75, 96, .9)),
                      child: ListTile(
                          onTap: (){
                            if(snapshot.data[index]["itinéraires"].length == 0 ){
                              showDialog(
                                  context: context,
                                  builder: (_) => NetworkGiffyDialog(
                                    buttonOkColor: Color.fromRGBO(64, 75, 96, .9),
                                    key: keys[1],
                                    image: Image.network(
                                      "https://raw.githubusercontent.com/Shashank020519.gif"            
                                      fit: BoxFit.cover,
                                    ),
                                    entryAnimation: EntryAnimation.DEFAULT,
                                    title: Text(
                                      'Pas encore defini',
                                      textAlign: TextAlign.center,
                                      style: TextStyle(
                                          fontSize: 22.0, fontWeight: FontWeight.w600),
                                    ),
                                    description: Text(
                                     "nothing"                
                                      textAlign: TextAlign.center,
                                    ),
                                    onOkButtonPressed: () {},
                                  ));
                            }else{
                              Navigator.push(
                                  context,
                                  MaterialPageRoute(
                                      builder: (context) => TimelinePage(title: 'suivi ${snapshot.data[index]["libelle_coli"]}',
                                        trajet:snapshot.data[index]["itinéraires"],
                                      )
                                  ));
                            }
                          },
                          contentPadding: EdgeInsets.symmetric(horizontal: 20.0, vertical: 10.0),
                          leading: Container(
                            padding: EdgeInsets.only(right: 12.0),
                            decoration: new BoxDecoration(
                                border: new Border(
                                    right: new BorderSide(width: 1.0, color: Colors.white24))),
                            child: Icon(Icons.autorenew, color: Colors.white),
                          ),
                          title: Text(
                            "${snapshot.data[index]["libelle_coli"]}",
                            style: TextStyle(color: Colors.white, fontWeight: FontWeight.bold),
                          ),
                          // subtitle: Text("Intermediate", style: TextStyle(color: Colors.white)),

                          subtitle:staut(index,snapshot.data),
                          trailing:
                          Icon(Icons.keyboard_arrow_right, color: Colors.white, size: 30.0)),
                    ),
                  );
                },
              );
          }
            //return null;
          }
      ),
      new Container(
        child: Center(
          child: Text("History"),
        ),
      ),
      MessagingWidget()
    ]),
    floatingActionButton: FloatingActionButton(
      onPressed: () {
        // Add your onPressed code here!
        Navigator.push(
            context,
            MaterialPageRoute(
                builder: (context) => Page_init()
            ));
      },
      child: Icon(Icons.add, color:Colors.amber,),
      backgroundColor: Color.fromRGBO(58, 66, 86, 1.0),
      tooltip: "register something",
    ),
  ),
);

请有人帮我吗？

Answer 1

试试这个：

final StreamController _counter = StreamController.broadcast();