Angular中的请求拦截的方法

environments                                          
├── environment.prod.ts                  // 生产环境使用的配置
└── environment.ts                       // 开发环境使用的配置

// enviroment.ts

export const environment = {
  baseUrl: '',
  production: false
};

// http-interceptor.service.ts

import { Injectable } from '@angular/core';
import {
  HttpEvent,
  HttpHandler,
  HttpInterceptor, // 拦截器
  HttpRequest, // 请求
} from '@angular/common/http';

import { Observable } from 'rxjs';
import { tap } from 'rxjs/operators';

import { environment } from 'src/environments/environment';

@Injectable({
  providedIn: 'root'
})
export class HttpInterceptorService implements HttpInterceptor {

  constructor() { }

  intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
    let secureReq: HttpRequest<any> = req;

    secureReq = secureReq.clone({
      url: environment.baseUrl + req.url
    });

    return next.handle(secureReq).pipe(
      tap(
        (response: any) => {
          // 处理响应的数据
          console.log(response)
        },
        (error: any) => {
          // 处理错误的数据
          console.log(error)
        }
      )
    )
  }
}

// app.module.ts

import { HttpClientModule, HTTP_INTERCEPTORS } from '@angular/common/http';
// 拦截器服务
import { HttpInterceptorService } from './services/http-interceptor.service';

providers: [
  // 依赖注入
  {
    provide: HTTP_INTERCEPTORS,
    useClass: HttpInterceptorService,
    multi: true,
  }
],

let secureReq: HttpRequest<any> = req;
// ...
// 使用 localhost 存储用户凭证，在请求头带上
if (window.localStorage.getItem('ut')) {
  let token = window.localStorage.getItem('ut') || ''
  secureReq = secureReq.clone({
    headers: req.headers.set('token', token)
  });
}

// ...