http/2 client example in clojure

1. Add [com.squareup.okhttp3/okhttp "3.9.1"] as dependecy in project.clj

2. Download  Jetty's ALPN boot JAR. from here

3. Add jvm options to boot ALPN and optionally truststore to JKS

:jvm-opts ["-Xbootclasspath/p:/opt/libs/alpn-boot-8.1.9.v20160720.jar"
                  "-Djavax.net.ssl.trustStore=test/keystore.jks"
                  "-Djavax.net.ssl.trustStorePassword=SecretPwd"]

4.  Simple http/2 client code looks like this.

(ns test01.core
  (:gen-class)
  (:import (okhttp3 OkHttpClient Request Request$Builder Response)))

(defn -main [& args]
  (let [client (OkHttpClient.)
        request (-> (Request$Builder.)
                    (.url "https://localhost:50443")
                    .build)
        response (-> client (.newCall request) .execute)]
    (println (-> response .body .string))
    (println (-> response .protocol .toString))))



(-main)