http2.go

package main

import (
  "fmt"
  "net/http"
  "golang.org/x/net/http2"
  "golang.org/x/net/http2/h2c"
  "crypto/tls"
  "net"
)

func client() {
    fmt.Println("s1")

    client := &http.Client{}
    client.Transport = &http2.Transport{
        AllowHTTP: true,
        DialTLS: func(netw, addr string, cfg *tls.Config) (net.Conn, error) {
            return net.Dial(netw, addr)
        }}

    resp, err := client.Get("http://localhost:8080/anc")
    fmt.Println(err)
    fmt.Println(resp)
}

func main() {

    handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        fmt.Fprint(w, "Hello world123")
    })
    h2s := &http2.Server{
        // ...
    }
    h1s := &http.Server{
        Addr:    ":8080",
        Handler: h2c.NewHandler(handler, h2s),
    }

    go h1s.ListenAndServe()

    client()
}