Angular6 和 RXJS6 的一些改动

例一：

import { Injectable } from '@angular/core';
import { Observable } from 'rxjs';
import { User } from "./model/User";
import { map } from 'rxjs/operators';
import { Http, Response, Headers, RequestOptions, URLSearchParams } from '@angular/http';


@Injectable({
  providedIn: 'root'
})

export class UserService {

  public userListURL = "api/users";
  constructor(public http: Http) {}

  public getUsers():Observable {
    return this.http.get(this.userListURL)
      .pipe(
        map((res: Response) => res.json().data as User[])
      )
  }
}