How to refresh StreamBuilder without Navigation and without Firebase - Flutter - firebase

Question

Currently my code works, but every 5 seconds I must make a request to the API, in order to refresh the view and see if any changes have occurred in the data.
My purpose is that it detect if there was any change in the data so that the view is updated, I am not using firebase and I am not trying to navigate to another screen either.
class _ListChatsState extends State<ListChats> {
final GlobalKey<ScaffoldState> scaffoldKey = new GlobalKey<ScaffoldState>();
final messagesProvider = new ServiceMessagesAdm();
Timer _timer;
#override
void initState() {
//messagesProvider.getMessagesAdm();
//Check the server every 5 seconds
_timer = Timer.periodic(Duration(seconds: 5), (timer) => messagesProvider.getMessagesAdm());
super.initState();
}
#override
void dispose() {
//cancel the timer
if (_timer.isActive) _timer.cancel();
super.dispose();
}
#override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.white,
key: scaffoldKey,
appBar: new AppBar(
title: new Text('StreamBuilder'),
actions: <Widget>[
],
),
body: FutureBuilder(
future: messagesProvider.getMessagesAdm(),
builder: (BuildContext context, AsyncSnapshot<List> snapshot) {
switch (snapshot.connectionState) {
case ConnectionState.none:
print("ESTOY EN NONE");
return image();
break;
case ConnectionState.waiting:
return Center(
child: CircularProgressIndicator(),
);
break;
case ConnectionState.active:
return _buildListView(snapshot.data);
break;
case ConnectionState.done:
// TODO: Handle this case.
break;
}
return image();
},
),
);
}
Future<List<MessagesAdm>> getMessagesAdm() async {
final respuesta = await http.get(url);
List<MessagesAdm> _list;
var resBody = json.decode(respuesta.body);
print(respuesta.body);
var capsules = resBody as List;
_list = capsules.map((model) => MessagesAdm.fromJson(model)).toList();
//print(_list);
popularesSink( _list );
return _list;
}
Is there a way to detect if there was any change within the API? I am chatting.
Before I was using these lines of code .. But they did not detect changes, for me it is important to tell you that the changes were being applied from postman. In the code, could I issue any notification that triggers those streams? I leave lines of the previous code used.
class ServiceMessagesAdm {
Loads loads;
final _popularesStreamController = StreamController<List<MessagesAdm>>.broadcast();
Function(List<MessagesAdm>) get popularesSink => _popularesStreamController.sink.add;
Stream<List<MessagesAdm>> get popularesStream => _popularesStreamController.stream;
void disposeStreams() {
_popularesStreamController?.close();
}
}