DIO MODEL

import 'dart:async';
import 'package:flutter/material.dart';
import 'dart:convert';
import 'package:dio/dio.dart';

void main()=>runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: HomePage()
    );
  }
}

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  StreamController _streamController;
  StreamSubscription _streamSubscription;
  StreamSink _streamSink;
  @override
  void dispose() {
    // TODO: implement dispose
    _streamController.close();
    super.dispose();
  }
  @override
  void initState() {
    // TODO: implement initState
    _streamController=StreamController.broadcast();
    _streamSink=_streamController.sink;
    _streamController.stream.listen(onData,onError:onError,onDone: onDone);
    super.initState();
  }
  onData(value){
    print(value);
  }
  onError(Error){Navigator.of(context).push(MaterialPageRoute(builder: (BuildContext context){}));}
  onDone(){print('done');}

  pauseStream(){
    _streamSubscription.pause();
  }
  resumeStream(){
    _streamSubscription.resume();
  }
  cancleStream(){
    _streamSubscription.cancel();
  }


  fetchData()async{
    var datas;
    Response response = await Dio().get("http://jsonplaceholder.typicode.com/posts");
    if(response.statusCode==200){
      final _responseData=response.data;
      datas=_responseData.map((item)=>User.fromJson(item));
    }else{throw Exception('faild to fetch data');}
    return datas;
  }

  addDataToStream()async{
    var datas;
    datas=await fetchData();
    _streamSink.add(datas);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: FutureBuilder(
        future: fetchData(),
        builder: (BuildContext context,AsyncSnapshot snapshot){
          print('snapshot_data:${snapshot.data}');
          print('connectionstate:${snapshot.connectionState}');
          if(snapshot.connectionState==ConnectionState.waiting){
            return Center(child: Text('loading...'),);
          }
          return ListView(
            children: snapshot.data.map<Widget>((item){
              return ListTile(
                title: Text(item.title),
                subtitle: Text(item.body),
                leading: Icon(Icons.description),
              );
            }).toList(),
          );
        },
      ),
      appBar: AppBar(title: Text('Rock U')),
      floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,
      floatingActionButton: FloatingActionButton(
        onPressed: (){
          addDataToStream();
        },
        child: Icon(Icons.add),
          ),
    );
  }
}

class User {
  final String title;
  final String body;
  final int userId;
  final int id;


  User(this.title, this.body,this.userId,this.id);

  User.fromJson(Map<String, dynamic> json)
      :title = json['title'],
       id=json['id'],
       userId=json['UserId'],
       body = json['body'];

  Map<String, dynamic> toJson() =>
      <String, dynamic>{
        'title': title,
        'body': body,
        'id':id,
        'userId':userId,
      };
}