import { HttpClientModule } from '@angular/common/http';

@NgModule({
 imports: [
 BrowserModule,
 // import HttpClientModule after BrowserModule.
 HttpClientModule,
 ],
 declarations: [
 AppComponent,
 ],
 bootstrap: [ AppComponent ]
})

### base-interceptor.ts

import { Injectable } from '@angular/core';
import {
 HttpEvent, HttpInterceptor, HttpHandler, HttpRequest,
 HttpErrorResponse
} from '@angular/common/http';
import { throwError } from 'rxjs'
import { catchError, retry } from 'rxjs/operators';

/*設置請求的基地址，方便替換*/
const baseurl = 'http://localhost:8360';

@Injectable()
export class BaseInterceptor implements HttpInterceptor {

 constructor() {}

 intercept(req, next: HttpHandler) {

 let newReq = req.clone({
 url: req.hadBaseurl ? `${req.url}` : `${baseurl}${req.url}`,
 });
 /*此處設置額外的頭部，token常用于登陸令牌*/
 if(!req.cancelToken) {
 /*token數(shù)據(jù)來源自己設置，我常用localStorage存取相關數(shù)據(jù)*/
 newReq.headers =
 newReq.headers.set('token', 'my-new-auth-token')
 }

 // send cloned request with header to the next handler.
 return next.handle(newReq)
 .pipe(
 /*失敗時重試2次，可自由設置*/
 retry(2),
 /*捕獲響應錯誤，可根據(jù)需要自行改寫，我偷懶了，直接用的官方的*/
 catchError(this.handleError)
 )
 }
 
 private handleError(error: HttpErrorResponse) {
 if (error.error instanceof ErrorEvent) {
 // A client-side or network error occurred. Handle it accordingly.
 console.error('An error occurred:', error.error.message);
 } else {
 // The backend returned an unsuccessful response code.
 // The response body may contain clues as to what went wrong,
 console.error(
 `Backend returned code ${error.status}, ` +
 `body was: ${error.error}`);
 }
 // return an observable with a user-facing error message
 return throwError(
 'Something bad happened; please try again later.');
 };
}

### index.ts

import { HTTP_INTERCEPTORS } from '@angular/common/http';

import { BaseInterceptor } from './base-interceptor';

/** Http interceptor providers in outside-in order */
export const httpInterceptorProviders = [
 { provide: HTTP_INTERCEPTORS, useClass: BaseInterceptor, multi: true },

];

/*
Copyright 2017-2018 Google Inc. All Rights Reserved.
Use of this source code is governed by an MIT-style license that
can be found in the LICENSE file at http://angular.io/license
*/

import { httpInterceptorProviders } from './http-interceptors/index'

@NgModule({
 declarations: [
 AppComponent
 ],
 imports: [
 BrowserModule,
 HttpClientModule
 ],
 providers: [
 httpInterceptorProviders
 ],
 bootstrap: [AppComponent]
})