methodmux.go

package main

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

type MethodMux struct {
	GET  http.Handler
	POST http.Handler
	PUT  http.Handler
}

func (mux *MethodMux) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	var methodMux http.Handler
	switch r.Method {
	case "GET":
		methodMux = mux.GET
	case "POST":
		methodMux = mux.POST
	case "PUT":
		methodMux = mux.PUT
	}
	if methodMux == nil {
		methodMux = http.DefaultServeMux
	}
	methodMux.ServeHTTP(w, r)
}

func main() {
	getMux := http.NewServeMux()
	postMux := http.NewServeMux()

	getMux.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {
		io.WriteString(w, "hello world\n")
	})
	postMux.HandleFunc("/foo", func(w http.ResponseWriter, req *http.Request) {
		io.WriteString(w, "post\n")
	})

	log.Fatal(http.ListenAndServe(":8080", &MethodMux{
		GET:  getMux,
		POST: postMux,
	}))
}