angular4拦截器的使用

不说废话直接上干货
在app-routing中：

import {AuthGuard} from './_guards/auth.guard';
const routes: Routes = [
   { path: '', component: HomeComponent,
       canActivate: [AuthGuard],
       children: [
       xxx
       xxx
       xxx
]
   },
];

下一步：配置 auth.guard

import {Injectable} from '@angular/core';
import {CanActivate, ActivatedRouteSnapshot, RouterStateSnapshot, Router} from '@angular/router';
import { SessionService } from 'app/shared/session.service';

@Injectable()
export class AuthGuard implements CanActivate {

 constructor(private router: Router,
     private sessionService: SessionService,
 ) {
 }

 canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): boolean {

   const user = this.sessionService.getCurrentUser() ; //get login user msg
   if (user&&user.id) {
     // logged in so return true
     return true;
   }

   // not logged in so redirect to login page with the return url
   if (state.url === '/') {
     console.log('没有登陆,直接跳转登陆页');
     this.router.navigate(['/login']);
   } else {
     console.log('没有登陆,访问子页面，直接跳转登陆页');
     this.router.navigate(['/login'], { queryParams: { returnUrl: state.url }});
   }
   return false;
 }
}

（不知道angular7是否可行，因为前段时间用了下ng7 发现内部http的封装已经改变了，国内外目前为止也没有针对ng7的详细文档）