Communiquer directement avec un socket

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.InetSocketAddress;
import java.net.MalformedURLException;
import java.net.Socket;
import java.net.URL;
import java.util.logging.Level;
import java.util.logging.Logger;
 
/**
 * Communiquer directement avec un socket
 * @author Fobec 2013
 * @see http://www.fobec.com/java/1130/communiquer-directement-avec-socket.html
 */
public class HttpRawSocket {
 
    private String request = ""; //commande envoye
    private String header=""; //reponse header
    private String html=""; //reponse html
    private String ua = null; //user agent
    private boolean gzip=false; //compression demande
 
    /**
     * Ouvrir un socket et envoyer une commande
     * @param aURL
     * @throws MalformedURLException
     * @throws IOException 
     */
    public void connect(String aURL) throws MalformedURLException, IOException {
        Socket socket = new Socket();
        URL url = new URL(aURL);
        socket.connect(new InetSocketAddress(url.getHost(), 80));
        try {
            InputStreamReader inputreader=new InputStreamReader(socket.getInputStream());
            BufferedReader reader = new BufferedReader(inputreader);
            PrintWriter writer = new PrintWriter(socket.getOutputStream(), true);
            //envoyer la requete
            this.request=this.buildCommand(url);
            writer.println(this.request);
            //receptionner la réponse
            String line;
            StringBuilder sb = new StringBuilder();
            while ((line = reader.readLine()) != null) {
                sb.append(line).append(System.getProperty("line.separator"));
            }
            //Séparer le header du code html
            String response = sb.toString();
            String tag=System.getProperty("line.separator")+System.getProperty("line.separator");
            int idx=response.indexOf(tag);       
            this.header = response.substring(0,idx);
            this.html = response.substring(idx+1);
        } finally {
            socket.close();
        }
    }
 
    /**
     * Fixer le UserAgent
     * @param useragent 
     */
    public void setUserAgent(String useragent) {
        this.ua = useragent;
    }
    //Fixer la compression
    public void setEncoding(boolean acceptGzip) {
        this.gzip = acceptGzip;
    }
    //Retourner la requete envoyé au serveur
    public String getRequest() {
        return this.request;
    }
    //Retourner le header de la réponse
    public String getHeader() {
        return this.header;
    }
    //retourner le code html
    public String getHtml() {
        return this.html;
    }
    /**
     * Assembler la requete à envoyer au serveur
     * @param url
     * @return 
     */
    private String buildCommand(URL url) {
        String cmd = "GET " + url.getPath() + " HTTP/1.1rn";
        cmd += "Host: " + url.getHost() + "rn";
        if (this.ua != null) {
            cmd += "User-Agent: "+this.ua+"rn";
        }
        if (this.gzip == true) {
            cmd += "Accept-Encoding: gzip, deflatern";
        }
 
        //Close
        cmd+="rn";        
 
        return cmd;
    }
}

public class HttpRawSocket {
 
    public static void main(String[] args) {
        HttpRawSocket httpSocket = new HttpRawSocket();
        try {
            httpSocket.setUserAgent("Exemple java de Fobec.com");
            httpSocket.connect("http://ubuntu-fr.org/telechargement");
 
            System.out.println(httpSocket.getRequest());
            System.out.println(httpSocket.getHeader());
            System.out.println(httpSocket.getHtml());
        } catch (MalformedURLException ex) {
            Logger.getLogger(HttpRawSocket.class.getName()).log(Level.SEVERE, null, ex);
        } catch (IOException ex) {
            Logger.getLogger(HttpRawSocket.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
}