在go文件服务器加入http.StripPrefix的用途介绍

package main
import (
 "flag"
 "fmt"
 "github.com/julienschmidt/httprouter"
 "log"
 "net/http"
 "strings"
 "time"
)
func main() {
 root := flag.String("p", "", "file server root directory")
 flag.Parse()
 if len(*root) == 0 {
 log.Fatalln("file server root directory not set")
 }
 if !strings.HasPrefix(*root, "/") {
 log.Fatalln("file server root directory not begin with '/'")
 }
 if !strings.HasSuffix(*root, "/") {
 log.Fatalln("file server root directory not end with '/'")
 }
 p, h := NewFileHandle(*root)
 r := httprouter.New()
 r.GET(p, LogHandle(h))
 log.Fatalln(http.ListenAndServe(":8080", r))
}
func NewFileHandle(path string) (string, httprouter.Handle) {
 return fmt.Sprintf("%s*files", path), func(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
 http.StripPrefix(path, http.FileServer(http.Dir(path))).ServeHTTP(w, r)
 }
}
func LogHandle(handle httprouter.Handle) httprouter.Handle {
 return func(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
 now := time.Now()
 handle(w, r, p)
 log.Printf("%s %s %s done in %v", r.RemoteAddr, r.Method, r.URL.Path, time.Since(now))
 }
}