server.go

package main

import (
    "fmt"
    "net/http"
)

// localhost:8080/ retrun exec folder
// localhost:8088/.... return same name file
// localhost:8080/handler return url path(from handler function)

func handler(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintf(w, r.URL.Path[1:])
}

func main() {
    http.HandleFunc("/handler", handler)
    http.Handle("/", http.FileServer(http.Dir("./")))
    http.ListenAndServe(":8080", nil)
}