minimal scala HTTP server (proof of concept, for courses)

Minimal_HTTP_FolderHelper

object FolderHelper {

  def list_files(item: File): Stream[File] = {
    item match {
      case file if (file.isFile()) => Stream(file)
      case dir if (dir.isDirectory()) =>
        Stream(dir) ++ dir.listFiles().toStream.flatMap { el => list_files(el) }
    }
  }

}

MinimalHTTPServer.scala

package scala.examples.web

import java.net.InetSocketAddress
import java.util.concurrent.Executors
import com.sun.net.httpserver.HttpExchange
import com.sun.net.httpserver.HttpHandler
import com.sun.net.httpserver.HttpServer
import java.io.BufferedReader
import java.io.InputStreamReader
import java.net.InetAddress
import java.net.URLDecoder
import scala.util.parsing.json.JSONObject
import scala.collection.JavaConversions._
import scala.collection.JavaConverters._
import scala.util.parsing.json.JSONArray
import java.util.logging.Logger
import java.util.logging.Level
import com.sun.net.httpserver.Headers

object MinimalHTTPServer extends App {

  val logger = Logger.getLogger(MinimalHTTPServer.getClass.toString())

  var hits = 0

  val executor = Executors.newSingleThreadExecutor()

  val server = HttpServer.create(new InetSocketAddress(8888), 0)
  server.createContext("/test", new HttpHandler() {

    def parseParams(exchange: HttpExchange) = {
      exchange.getRequestURI().getQuery
        .split("&").toList
        .foldRight(Map.empty[String, String])((qp, map) => {
          val p = qp.split("=").map { x => URLDecoder.decode(x, "UTF-8") }
          map + (p(0) -> p(1))
        })
    }

    def parseHeaders(exchange: HttpExchange) = {
      exchange.getRequestHeaders
        .map { h =>
          val values = h._2.toList
          if (values.size > 1)
            (h._1, JSONArray(values))
          else
            (h._1, values(0))
        }
        .toMap
    }

    override def handle(exchange: HttpExchange) {

      val uri = exchange.getRequestURI()
      val msg = s"REQUEST[$hits]: $uri"
      val query = uri.getQuery
      val params = parseParams(exchange)
      val headers = parseHeaders(exchange)

      val json = JSONObject(Map(
        "msg" -> msg,
        "query" -> query,
        "params" -> JSONObject(params),
        "headers" -> JSONObject(headers)))

      logger.log(Level.INFO, json.toString())

      exchange.sendResponseHeaders(200, json.toString().length())
      val os = exchange.getResponseBody()
      os.write(json.toString().getBytes())
      os.flush()
      os.close()

      hits = hits + 1
    }

  })

  server.setExecutor(executor); // creates a default executor
  server.start();

}

MinimalHTTPServer_with_HTML.scala

package scala.examples.web

import java.net.InetSocketAddress
import java.util.concurrent.Executors
import com.sun.net.httpserver.HttpExchange
import com.sun.net.httpserver.HttpHandler
import com.sun.net.httpserver.HttpServer
import java.io.BufferedReader
import java.io.InputStreamReader
import java.net.InetAddress
import java.net.URLDecoder
import scala.util.parsing.json.JSONObject
import scala.collection.JavaConversions._
import scala.collection.JavaConverters._
import scala.util.parsing.json.JSONArray
import java.util.logging.Logger
import java.util.logging.Level
import com.sun.net.httpserver.Headers
import java.awt.Color
import scala.util.parsing.json.JSONObject

object MinimalHTTPServer_with_HTML extends App {

  val logger = Logger.getLogger(MinimalHTTPServer.getClass.toString())

  var hits = 0

  val executor = Executors.newSingleThreadExecutor()

  val server = HttpServer.create(new InetSocketAddress(8888), 0)
  server.createContext("/test", new HttpHandler() {

    def parseParams(exchange: HttpExchange) = {
      exchange.getRequestURI().getQuery
        .split("&").toList
        .foldRight(Map.empty[String, String])((qp, map) => {
          val p = qp.split("=").map { x => URLDecoder.decode(x, "UTF-8") }
          map + (p(0) -> p(1))
        })
    }

    def parseHeaders(exchange: HttpExchange) = {
      exchange.getRequestHeaders
        .map { h =>
          val values = h._2.toList
          if (values.size > 1)
            (h._1, JSONArray(values))
          else
            (h._1, values(0))
        }
        .toMap
    }

    override def handle(exchange: HttpExchange) {

      val uri = exchange.getRequestURI()
      val msg = s"REQUEST[$hits]: $uri"
      val query = uri.getQuery
      val params = parseParams(exchange)
      val headers = parseHeaders(exchange)

      val map = Map(
        "msg" -> msg,
        "query" -> query,
        "params" -> params,
        "headers" -> headers)

      logger.log(Level.INFO, map.toString())

      val user = params.get("user").get
      val color = params.get("color").get

      val html = HTMLPage(
        "this is the example page! :-)",
        user,
        color,
        map.mkString("\n"))
        .html.toString()

      exchange.sendResponseHeaders(200, html.length())
      val os = exchange.getResponseBody()

      os.write(html.getBytes)

      os.flush()
      os.close()

      hits = hits + 1
    }

  })

  server.setExecutor(executor); // creates a default executor
  server.start();

}

case class HTMLPage(title: String, user: String, bgcolor: String = "#FFF", json: String = "{}") {

  val css = """
  #json{
    width: 60%; height: auto;
    padding: 2em 1em;
    overflow: scroll;
  }  
  """

  def message = s"Welcome <b>$user</b>! :-)"

  val html =
    <html>
      <head>
        <meta charset="utf-8"/>
        <style>{ css }</style>
      </head>
      <body>
        <p style={ "background-color: " + bgcolor }>{ message }</p>
        <script src="//d3js.org/d3.v3.min.js"></script>
        <script>
          d3.select('body').append('span').text('Hello, world!').style('background-color', '#FF0');
        </script>
        <pre id="json">{ json.toString() }</pre>
      </body>
    </html>

}