/******
** @创建时间 : 2020/5/25 20:26
** @作者 : SongZhiBin
******/
package share

import (
	"fmt"
	"net/http"
	"net/http/httputil"
	"net/url"
	"os"
)

// ========= global variable
var Config conf
var LogOut *os.File

// ========== Struct
type conf struct {
	TargetIP   string
	TargetPort int
	LocalPort  int
}

// 转发中间件
func (c *conf) Forward(w http.ResponseWriter, r *http.Request) {
	u, _ := url.Parse(fmt.Sprintf("http://%s:%d/", Config.TargetIP, Config.TargetPort))
	proxy := httputil.NewSingleHostReverseProxy(u)
	proxy.ServeHTTP(w, r)
}

[target]
TargetIP = 127.0.0.1
TargetPort = 8080
LocalPort = 80

/******
** @创建时间 : 2020/5/25 19:09
** @作者 : SongZhiBin
******/
package main

import (
	"fmt"
	"gopkg.in/ini.v1"
	"net/http"
	"os"
)
import "Songzhibin/HttpAgent/share"

func main() {
	// 读取配置文件
	share.LogOut = os.Stdout
	cfg, err := ini.Load("./config.txt")
	if err != nil {
		// 读取失败,使用默认配置
		share.Config.TargetIP = "127.0.0.1"
		share.Config.TargetPort = 80
		share.Config.LocalPort = 80
		fmt.Fprintf(share.LogOut, "使用默认配置->TargetIP:%s TargetPort:%d\n", share.Config.TargetIP, share.Config.TargetPort)
	}

	err = cfg.Section("target").MapTo(&share.Config)
	if err != nil {
		fmt.Fprintf(share.LogOut, "MapTo映射失败->Err:%s\n", err)
		return
	}
	fmt.Fprintf(share.LogOut, "配置文件启动->TargetIP:%s TargetPort:%d\n", share.Config.TargetIP, share.Config.TargetPort)
	http.HandleFunc("/", share.Config.Forward)                                 // 设置默认路由
	err = http.ListenAndServe(fmt.Sprintf(":%d", share.Config.LocalPort), nil) 
	if err != nil {
		fmt.Printf("http server failed, err:%v\n", err)
		return
	}
}