问如何在Golang中设置Cookie（net/ HTTP）？

package main

import "io"
import "net/http"
import "time"

func indexHandler(w http.ResponseWriter, req *http.Request) {
    expire := time.Now().AddDate(0, 0, 1)
    cookie := http.Cookie{"test", "tcookie", "/", "www.domain.com", expire, expire.Format(time.UnixDate), 86400, true, true, "test=tcookie", []string{"test=tcookie"}}
    req.AddCookie(&cookie)
    io.WriteString(w, "Hello world!")
}

func main() {
    http.HandleFunc("/", indexHandler)
    http.ListenAndServe(":80", nil)
}