httpExample.go

package main

import (
	"fmt"
	"net/http"
	"strconv"
	"strings"
)

func main() {
	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		pathArray := strings.Split(r.URL.Path, "/")[1:]

		pathHead := pathArray[0]

		if pathHead == "echo" {
			var echoString string
			if len(pathArray) <= 1 {
				echoString = ""
			} else {
				echoString = pathArray[1]
			}
			fmt.Fprint(w, echoString)
		} else if pathHead == "add" && len(pathArray) >= 3 {
			l, lErr := strconv.ParseInt(pathArray[1], 10, 64)
			r, rErr := strconv.ParseInt(pathArray[2], 10, 64)

			if lErr != nil || rErr != nil {
				w.WriteHeader(400)
				fmt.Fprint(w, "Parameter is not a integer.")
			} else {
				fmt.Fprint(w, l+r)
			}
		} else {
			w.WriteHeader(404)
			fmt.Fprint(w, "Not Found")
		}

	})

	http.ListenAndServe(":8080", nil)
}