net/httputil

httputil包提供了HTTP公用函数，是对net/http包的更常见函数的补充

• 反向代理的实现

NewSingleHostReverseProxy返回一个新的ReverseProxy。返回值会将请求的URL重写为target参数提供的协议、主机和基路径。如果target参数的Path字段为"/base"，接收到的请求的URL.Path为"/dir"，修改后的请求的URL.Path将会是"/base/dir"
func NewSingleHostReverseProxy(target *url.URL) *ReverseProxy
func (p *ReverseProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request)

ReverseProxy是一个HTTP处理器，它接收一个请求，发送给另一个服务端，将回复转发给客户端

package main

import (
    "net/http"
    "net/http/httputil"
    "net/url"
)
func main() {
   http.HandleFunc("/index.html", func(writer http.ResponseWriter, request *http.Request) {
      url,_:=url.ParseRequestURI("http://www.baidu.com")
     reverseProxy :=  httputil.NewSingleHostReverseProxy(url)
     reverseProxy.ServeHTTP(writer,request)
   })
   http.ListenAndServe(":8080",nil)
}

当我们请求http://localhost:8080/index.html ,系统会自动代理到http://www.baidu.com主机上,实际方位的地址为http://www.baidu.com/index.html