小编SS_*_*uck的帖子

我正在尝试使Angular 4中的代码适应Angular5。我进行了很多更改，但是关于出现错误RequestOptions。该代码是关于身份验证的，这是我出现错误的地方：

  import { Injectable } from '@angular/core';
   import { RequestOptions} from '@angular/http';
   import {User} from '../model/model.user';
   import 'rxjs/add/operator/map';
    import {HttpClient, HttpHeaders} from '@angular/common/http';

  @Injectable()
  export class AuthService {
  constructor(public http: HttpClient) { }

    public logIn(user: User) {

const headers = new HttpHeaders();
headers.append('Accept', 'application/json')
// creating base64 encoded String from user name and password
const base64Credential: string = btoa( user.username + ':' + user.password);
headers.append('Authorization', 'Basic ' + base64Credential);
     // this is where i'm having a problem …