Go Exercise: HTTP Handlers - http://tour.golang.org/methods/14

httpHandler.go

package main

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

// type Hello implements http.Handler
type Hello struct{}

func (this Hello) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	fmt.Fprintf(w, "Hello!")
}

type String string

func (this String) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	fmt.Fprint(w, this)
}

type Struct struct {
	Greeting string
	Punct    string
	Who      string
}

func (this Struct) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	fmt.Fprint(w, this.Greeting, this.Punct, this.Who)
}

func main() {
	http.Handle("/", Hello{})
	http.Handle("/string", String("I'm a frayed knot."))
	http.Handle("/struct", &Struct{"Hello", ":", "Gophers!"})

	if err := http.ListenAndServe("localhost:4000", nil); err != nil {
		log.Fatal(err)
	}
}