带有HTTP请求和Observable的Angular2身份验证防护

我目前正在使用Spring Boot作为后端实现angular2示例应用程序。我在前端身份验证保护机制和可观察变量方面遇到了一些问题。

我正在努力实现：

1. 当有人输入受保护的路由时，auth防护人员应检查auth服务变量中是否已经设置了用户
2. 如果未设置，则应该发出http请求以检查会话是否可用
3. 服务方法应返回true / false值（由于可能有http请求，因此它是异步的）
4. 如果服务返回false，则身份验证防护应重定向到登录页面
5. auth Guard应该返回true / false，因此路由可以激活或不激活

我的代码当前看起来像这样（我正在使用RC5 btw。）：

验证卫士

import {Injectable} from "@angular/core";
import {CanActivate, ActivatedRouteSnapshot, RouterStateSnapshot, Router} from "@angular/router";
import {Observable, Subject} from "rxjs/Rx";
import {AuthService} from "./auth.service";

@Injectable()
export class AuthGuard implements CanActivate {
  constructor(private authService: AuthService, private router: Router) {}

  canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): Observable<boolean> | boolean {
    var authenticated = this.authService.isAuthenticated();
    var subject = new Subject<boolean>();
    authenticated.subscribe(
        (res) => {
          console.log("onNext guard: "+res);
          if(!res && state.url !== '/signin') {
            console.log("redirecting to signin")
            this.router.navigate(['/signin']);
          }
          subject.next(res);
        });
    return subject.asObservable();
  }
}

验证服务

import {Injectable} from "@angular/core";
import {User} from "./user.interface";
import {Router} from "@angular/router";
import {Http, Response, Headers} from "@angular/http";
import {environment} from "../environments/environment";
import {Observable, Observer, Subject} from "rxjs/Rx";

@Injectable()
export class AuthService {
  private authenticatedUser : User;
  constructor(private router: Router, private http: Http) {}

  signupUser(user: User) {
  }


  logout() {
    //do logout stuff
    this.router.navigate(['/signin']);
  }

  isAuthenticated() : Observable<boolean> {
    var subject = new Subject<boolean>();
    if (this.authenticatedUser) {
      subject.next(true);
    } else {
      this.http.get(environment.baseUrl + '/user')
        .map((res : Response) => res.json())
        .subscribe(res => {
          console.log("next: returning true");
          this.authenticatedUser = User.ofJson(res);
          subject.next(true);
        }, (res) => {
          console.log("next: returning false");
          subject.next(false);
        });
    }
    return subject.asObservable();
  }
}

问题是：即使我登录后，防护也永远不会激活路由器组件。

谢谢您的帮助！