angular之intercepter

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

@Injectable()
export class TokenInterceptor implements HttpInterceptor {
  intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    request = request.clone({
      setHeaders: {
        Authorization: `${localStorage.token}`
      }
    });

    return next.handle(request);
  }
}

// app.module.ts
providers: [
    {
      provide: HTTP_INTERCEPTORS,
      useClass: TokenInterceptor,
      multi: true
    }
  ]

然后尴尬的一幕出现了，intercepter只在登录前被成功调用了，要用到sessionToken的时候反而罢工了。
google了半天，发现不能有多个HttpClientModule声明。