本篇文章带大家继续angular的学习，简单了解一下Angular中的Http处理，介绍一下错误处理和请求拦截，希望对大家有所帮助！

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基本使用

用 Angular 提供的 HttpClient 可以很轻松的实现 API 接口的访问。【相关教程推荐：《angular教程》】


(资料图片仅供参考)

举个例子 新建一个 http.service.ts可以在 environment中配置不同环境的 host 地址

再贴一下 proxy.config.json第一章中有介绍到

{  "/api": {    "target": "http://124.223.71.181",    "secure": true,    "logLevel": "debug",    "changeOrigin": true,    "headers": {      "Origin": "http://124.223.71.181"    }  }}
import { HttpClient } from "@angular/common/http";import { Injectable } from "@angular/core";import { environment } from "@env";@Injectable({ providedIn: "root" })export class HttpService {  constructor(private http: HttpClient) {}  public echoCode(method: "get" | "post" | "delete" | "put" | "patch" = "get", params: { code: number }) {    switch (method) {      case "get":      case "delete":        return this.http[method](`${environment.backend}/echo-code`, { params });      case "patch":      case "put":      case "post":        return this.http[method](`${environment.backend}/echo-code`, params);    }  }}

然后在业务中 我们就可以这样使用

import { Component, OnInit } from "@angular/core";import { HttpService } from "./http.service";@Component({  selector: "http",  standalone: true,  templateUrl: "./http.component.html",})export class HttpComponent implements OnInit {  constructor(private http: HttpService) {}  ngOnInit(): void {    this.http.echoCode("get", { code: 200 }).subscribe(console.log);    this.http.echoCode("post", { code: 200 }).subscribe(console.log);    this.http.echoCode("delete", { code: 301 }).subscribe(console.log);    this.http.echoCode("put", { code: 403 }).subscribe(console.log);    this.http.echoCode("patch", { code: 500 }).subscribe(console.log);  }}

这看起来非常简单 类似 Axios

下面介绍一下一些常用的用法

错误处理

this.http  .echoCode("get", { code: 200 })  .pipe(catchError((err: HttpErrorResponse) => of(err)))  .subscribe((x) => {    if (x instanceof HttpErrorResponse) {      // do something    } else {      // do something    }  });

请求拦截

请求拦截是比较常用的

例如 你可以在这里判断 cookie 是否有效 / 全局错误处理 ...

新建 http-interceptor.ts文件 （ 文件名可以随意 ）

最主要的是要实现 HttpInterceptor的 intercept方法

import { HttpInterceptor, HttpRequest, HttpHandler, HttpResponse, HttpErrorResponse } from "@angular/common/http";import { Injectable } from "@angular/core";import { Observable, of, throwError } from "rxjs";import { filter, catchError } from "rxjs/operators";import { HttpEvent } from "@angular/common/http";@Injectable()export class HttpInterceptorService implements HttpInterceptor {  constructor() {}  intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {    return next      .handle(req)      .pipe(filter((event) => event instanceof HttpResponse))      .pipe(        catchError((error) => {          console.log("catch error", error);          return of(error);        })      );  }}

然后在 module 中的 providers 中使用 这个拦截器就生效了

@NgModule({  imports: [RouterModule.forChild(routes)],  exports: [RouterModule],  providers: [    {      provide: HTTP_INTERCEPTORS,      useClass: HttpInterceptorService,      multi: true,    },  ],})export class XXXModule {}

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