拦截器为什么会触发两次？

[xuedongliu]

import {Injectable} from '@angular/core';
import {HttpEvent, HttpHandler, HttpInterceptor, HttpRequest, HttpResponse} from '@angular/common/http';
import {Router} from '@angular/router';
import {tap} from 'rxjs/operators';
import {Observable} from 'rxjs';

@Injectable()
export class Interceptor implements HttpInterceptor {
  constructor(private router: Router) {
  }

  intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    console.log(req);
    const c = req.clone({
      url: '/test/' + req.url,
      withCredentials: true
    });
    // debugger;
    return next.handle(c).pipe(
      tap(
        event => {
          if (event instanceof HttpResponse) {
            console.log(event);
            switch (event.body.code) {
              case 'no_login':
                this.router.navigate(['/login']);
            }
          }
        },
        error => {
          console.error(error);
        }
      )
    );
  }
}

然后在modue中

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';

import { BootRoutingModule } from './boot-routing.module';
import { ErrorComponent } from './error/error.component';
import {BootComponent} from './boot/boot.component';
import { LoginComponent } from './login/login.component';
import { AbsPipe } from './pipe/abs.pipe';
import {HttpClientModule} from '@angular/common/http';
import {Interceptor} from './interceptor/interceptor';
import {CommunicationService} from './service/communication.service';

@NgModule({
  declarations: [
    BootComponent,
    ErrorComponent,
    LoginComponent,
    AbsPipe
  ],
  imports: [
    BrowserModule,
    BootRoutingModule,
    HttpClientModule
  ],
  providers: [
   {
      provide: HTTP_INTERCEPTORS,
      useClass: Interceptor,
      multi: true
    },
    CommunicationService
  ],
  bootstrap: [BootComponent]
})
export class BootModule { }

这样写会触发两次拦截器，但是只发起了一次请求。 如果我请求的URL是‘/getfunc’,我想要的是‘/test/getfunc’，最后发起请求的却是‘/test/test/getfunc’ 请问一下这是为什么？ 我的angular版本是 ` Angular CLI: 6.2.9 Node: 11.14.0 OS: darwin x64 Angular: 6.1.10 ... animations, common, compiler, compiler-cli, core, forms ... http, language-service, platform-browser ... platform-browser-dynamic, router

Package Version

@angular-devkit/architect 0.8.9 @angular-devkit/build-angular 0.8.9 @angular-devkit/build-optimizer 0.8.9 @angular-devkit/build-webpack 0.8.9 @angular-devkit/core 0.8.9 @angular-devkit/schematics 0.8.9 @angular/cli 6.2.9 @ngtools/webpack 6.2.9 @schematics/angular 0.8.9 @schematics/update 0.8.9 rxjs 6.2.2 typescript 2.9.2 webpack 4.16.4 `

[asnowwolf]

到 stackblitz 做个 live demo?