http middleware log

httplog.go

package main

import (
	"log"
	"net/http"
	"os"
)

type Adapter func(http.Handler) http.Handler

func Notify(logger *log.Logger) Adapter {
	return func(h http.Handler) http.Handler {

		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			logger.Println("before")
			h.ServeHTTP(w, r)
			logger.Println("after")
		})
	}
}

func main() {
	l := log.New(os.Stdout, "HTTP | ", log.LstdFlags|log.Lshortfile)
	l2 := log.New(os.Stderr, "", log.LstdFlags)

	f := func(w http.ResponseWriter, _ *http.Request) {
		w.Write([]byte("hello"))
		l2.Println("during")
	}

	http.Handle("/", Notify(l)(http.HandlerFunc(f)))
	http.ListenAndServe(":8888", nil)

}

out.txt

HTTP | 2016/09/19 15:51:55 test.go:15: before
2016/09/19 15:51:55 during
HTTP | 2016/09/19 15:51:55 test.go:17: after
HTTP | 2016/09/19 15:51:55 test.go:15: before
2016/09/19 15:51:55 during
HTTP | 2016/09/19 15:51:55 test.go:17: after