我们如何在angularjs2中的http observable中添加另一个订阅操作？

如果你使UserService.login()返回observable(不是订阅者,就像现在一样),你可以在LoginComponent中订阅它

export class UserService {
  login(username: string, password: string) {

    return this._utils.api(request)
      .map(response => response.json())
    );
  }
}

export class LoginComponent implements OnInit {
  submitLogin() {
    var p = this._userService
      .login(this.username, this.password)
      .subscribe(

        // success
        (data) => { 
          this._userService.setAccessToken(data.access_token); 
          // redirect here...
        }, 

        // error
        (error) => {}, 

        // completed
        () => {}  
      )
  }
}