用Go实现网关

package main

import (
  "encoding/json"
  "fmt"
  "io"
  "net/http"
  "regexp"
  "strings"
)

var ServiceMap = map[string]string{
  "auth":  "http://127.0.0.1:20021",
  "user":  "http://127.0.0.1:20022",
  "chat":  "http://127.0.0.1:20023",
  "group": "http://127.0.0.1:20024",
}

type Data struct {
  Code int    `json:"code"`
  Data any    `json:"data"`
  Msg  string `json:"msg"`
}

func toJson(data Data) []byte {
  byteData, _ := json.Marshal(data)
  return byteData
}

func gateway(res http.ResponseWriter, req *http.Request) {
  p := req.URL.Path
  regex, _ := regexp.Compile(`/api/(.*?)/`)
  list := regex.FindStringSubmatch(p)
  if len(list) != 2 {
    res.Write(toJson(Data{Code: 7, Msg: "服务错误"}))
    return
  }
  addr, ok := ServiceMap[list[1]]
  if !ok {
    res.Write(toJson(Data{Code: 7, Msg: "服务错误"}))
    return
  }
  // 转发到实际服务上
  url := addr + req.URL.String()

  proxyReq, _ := http.NewRequest(req.Method, url, req.Body)
  proxyReq.Header = req.Header
  remoteAddr := strings.Split(req.RemoteAddr, ":")
  if len(remoteAddr) != 2 {
    res.Write(toJson(Data{Code: 7, Msg: "服务错误"}))
    return
  }
  fmt.Printf("%s %s =>  %s\n", remoteAddr[0], list[1], url)
  proxyReq.Header.Set("X-Forwarded-For", remoteAddr[0])
  proxyResponse, err := http.DefaultClient.Do(proxyReq)
  if err != nil {
    res.Write(toJson(Data{Code: 7, Msg: "服务错误"}))
    return
  }
  io.Copy(res, proxyResponse.Body)
  return
}

func main() {
  // 回调函数
  http.HandleFunc("/", gateway)
  // 绑定服务
  fmt.Printf("fim_gateway 运行在：%s\n", "http://127.0.0.1:9000")
  http.ListenAndServe(":9000", nil)
}