sample of: http://nesv.blogspot.tw/2012/09/super-easy-json-http-responses-in-go.html

go-json.go

package main

import (
	"fmt"
	"log"
	"net/http"
	"encoding/json"
)

type Response map[string]interface{}

func (r Response) String() (s string) {
	b, err := json.Marshal(r)
	if err != nil {
		s = ""
		return
	}

	s = string(b)
	return
}

func myHandler (w http.ResponseWriter, req *http.Request) {
	w.Header().Set("Content-Type", "application/json")
	fmt.Fprint(w, Response{"success": true, "message": "Hello"})

	return
}

func main() {
	http.HandleFunc("/", myHandler)

	err := http.ListenAndServe(":3000", nil)

	if err != nil {
		log.Fatal("Listen and serve error: ", err)
	}
}