FakeHTTP.rb

require 'java'
# java.io.IOException
# java.net.InetSocketAddress
# net.fiorix.niosted.Factory
# net.fiorix.niostedi.TCPServer
# net.fiorix.niosted.protocols.LineReceiver
#
require 'niosted.jar'
import "net.fiorix.niosted.protocols.LineReceiver"
import "net.fiorix.niosted.Factory"
import "net.fiorix.niosted.TCPServer"

class FakeProtocol < LineReceiver
  def lineReceived(line)
    if line.nil?
      puts "Got header #{line}"
    else
      self.transport.write "HTTP/1.1 200 OK\r\n"+
                            "Etag: \"b32ffe9242ccde98d6e19ed4c9dbc053d4a18155\"\r\n"+
                            "Content-Length: 14\r\n"+
                            "Content-Type: text/html; charset=UTF-8\r\n"+
                            "Server: CycloneServer/0.1\r\n\r\n"+
                            "Hello, world\r\n"
      self.transport.loseConnection()
    end 
  end 

  def connectionMade()
   cl = self.transport.getPeer()
   puts "new client connected: #{cl}"  
  end 

  def connectionLost(reason)
    puts "connection lost: #{reason}"
  end 
end

class FakeFactory
  include Factory

  def makeProtocol()
    return FakeProtocol.new
  end
end

addr = java.net.InetSocketAddress.new("0.0.0.0", 8888)
c = TCPServer.new(addr, FakeFactory.new)
c.run()

já sacou o null ali né malandragem :)