package main
 
import (
    "net/http"
)
 
func SayHello(w http.ResponseWriter, req *http.Request) {
    w.Write([]byte("Hello"))
}
 
func main() {
    http.HandleFunc("/hello", SayHello)
    http.ListenAndServe("localhost:8001", nil)
 
}

go实在是bt，两行就搞定了。