go 原生http web 服务跨域restful api的写法介绍

错误写法

func main() {    openHttpListen()}func openHttpListen() {    http.HandleFunc("/", receiveClientRequest)    fmt.Println("go server start running...")    err := http.ListenAndServe(":9090", nil)    if err != nil {        log.Fatal("ListenAndServe: ", err)    }}func receiveClientRequest(w http.ResponseWriter, r *http.Request) {    w.Header().Set("Access-Control-Allow-Origin", "*")             //允许访问所有域    w.Header().Add("Access-Control-Allow-Headers", "Content-Type") //header的类型    w.Header().Set("content-type", "application/json")             //返回数据格式是json    r.ParseForm()    fmt.Println("收到客户端请求: ", r.Form)

这样还是会报错：

说没有得到响应跨域的头，chrome的network中确实没有响应Access-Control-Allow-Origin

正确写法：

func LDNS(w http.ResponseWriter, req *http.Request) {    if origin := req.Header.Get("Origin"); origin != "" {        w.Header().Set("Access-Control-Allow-Origin", origin)        w.Header().Set("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE")        w.Header().Set("Access-Control-Allow-Headers",            "Accept, Content-Type, Content-Length, Accept-Encoding, X-CSRF-Token, Authorization")    }    if req.Method == "OPTIONS" {        return    }    // 响应http code    w.WriteHeader(200)    query := strings.Split(req.Host, ".")    value, err := ldns.RAMDBMgr.Get(query[0])    fmt.Println("Access-Control-Allow-Origin", "*")    if err != nil {        io.WriteString(w, `{"message": ""}`)        return    }    io.WriteString(w, value)}

补充：go http允许跨域

1.创建中间件

import ( "github.com/gin-gonic/gin" "net/http")// 跨域中间件func Cors() gin.HandlerFunc { return func(c *gin.Context) {  method := c.Request.Method  origin := c.Request.Header.Get("Origin")  if origin != "" {   c.Header("Access-Control-Allow-Origin", origin)   c.Header("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE, UPDATE")   c.Header("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept, Authorization")   c.Header("Access-Control-Expose-Headers", "Content-Length, Access-Control-Allow-Origin, Access-Control-Allow-Headers, Cache-Control, Content-Language, Content-Type")   c.Header("Access-Control-Allow-Credentials", "false")   c.Set("content-type", "application/json")  }  if method == "OPTIONS" {   c.AbortWithStatus(http.StatusNoContent)  }  c.Next() }}

2.在route中引用中间件

router := gin.Default()// 要在路由组之前全局使用「跨域中间件」, 否则OPTIONS会返回404router.Use(Cors())

以上为个人经验，希望能给大家一个参考，也希望大家多多支持服务器之家。如有错误或未考虑完全的地方，望不吝赐教。

原文链接：https://blog.csdn.net/guoer9973/article/details/54341637