Go http handler 中间件

在http的handler处理中加上中间件，可以进行过滤、记录日志、统计和统一返回结果

 package main import (     "fmt"     "net/http"     "encoding/json" ) func main() {     _ = fmt.Println     http.Handle("/test", FormatReturnHandler(HomeHandler))     http.ListenAndServe(":8000", nil) } type normalFunc func(r *http.Request) interface{} type Response struct {     Code int         `json:"code"`     Data interface{} `json:"data"`     Msg  string      `json:"msg"` } func FormatReturnHandler(f normalFunc) http.Handler {     return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {         fmt.Println(r.URL.Path)         ret := Response{}         ret.Data = f(r)         ret.Code = 0         ret.Msg = ""         jsonRet, _ := json.Marshal(&ret)         w.Write(jsonRet)     }) } func HomeHandler(r *http.Request) interface{} {     return r.Host }