ng4-http.ts

// create json file in assets folder

// in app.module.ts
import { HttpModule } from '@angular/http';

imports: [
    BrowserModule,
    FormsModule,
    HttpModule
  ],


// in services.ts
import { Injectable } from '@angular/core';
import { Http } from '@angular/http';
import 'rxjs/add/operator/map';

@Injectable()
export class MyDataService {

  constructor(private http: Http) { }

  fetchData(){
      this.http.get('./assets/data/student.json').map(
          (response) => response.json()
      ).subscribe(
          (data) => console.log(data)
      );
  }

  obj = {
      id:"1",
      name:"open",
      rollno:"2233"
  }


  success(){return "Successful" ;}

}



//in app.component.ts
import { Component } from '@angular/core';
import { MyDataService } from './my-data.service';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  title = 'app works!';

  constructor(private newServices: MyDataService){}

  ngOnInit(){
      console.log(this.newServices.success());
       console.log(this.newServices.obj);
       this.newServices.fetchData();

  }
}