简易的HTTP服务器，用于检测各种HTTP Client对KeepAlive的支持

http.clj

(ns me.zzp.http
  (:require [clojure.string :refer [blank?]])
  (:import java.io.PrintStream
           java.net.ServerSocket
           java.util.Scanner
           java.util.concurrent.atomic.AtomicLong)
  (:gen-class))

(defonce generitor (AtomicLong.))

(defn info [id message]
  (println (format "[%d] %s" id message)))

(defn http-read-header [scanner]
  (loop [content-length 0
         headers (StringBuilder.)]
    (let [line (if (.hasNextLine scanner) (.nextLine scanner) "")]
      (if (blank? line)
        [content-length (.toString headers)]
        (recur (if-let [[_ length] (re-matches #"Content-Length: (\d+)" line)]
                 (Long/parseLong length)
                 content-length)
               (.. headers
	         (append "\n  ")
	         (append line)))))))

(defn http-read [scanner]
  (let [[length headers] (http-read-header scanner)]
    (if (zero? length)
      headers
      (apply str headers "\n  "
        (for [_ (range length)]
          (if (.hasNext scanner "(?s).")
            (.next scanner "(?s).")
            ""))))))

(defn http-write [stream message]
  (. stream print
    (format "HTTP/1.1 200 OK\r\nContent-Type: text/plain; charset=utf-8\r\nContent-Length: %d\r\n\r\n%s" (alength (.getBytes message)) message)))

(defn process [logger client]
  (logger "open")
  (let [scanner (.useDelimiter (Scanner. (.getInputStream client)) "")
        stream (PrintStream. (.getOutputStream client))]
    (while (.hasNextLine scanner)
      (logger "receive request")
      (logger (http-read scanner))
      (logger "send response")
      (http-write stream "OK")
      (logger "done")))
  (.close client)
  (logger "close"))

(defn -main [& args]
  (let [server (ServerSocket. (int 8000))]
    (println "server start @ 8000")
    (loop []
      (let [client (.accept server)]
        (future (process (partial info (.incrementAndGet generitor)) client))
        (recur)))))