package serveur_mt;

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;

public class Serveur {
    public final static int DEFAULT_PORT = 6789;
    protected static int port;


    public static void main(String[] args) {
        ServerSocket listen_socket=null;
        if(args.length>0) {
            try {
            port=Integer.parseInt(args[0]);
            }catch(NumberFormatException nfe) {
                usage();
                System.out.println(nfe);
                System.exit(-1);
            }

        }else {
            port=DEFAULT_PORT;
        }

    //création de la socket d'écoute du serveur
        try {
            listen_socket=new ServerSocket(port);

        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        //boucle infinie du serveur
        //on attend des connexions clientes
        while(true) {

            try {
                Socket client=listen_socket.accept();
                Service s=new Service(client);
                s.start(); //démarrage du thread de service



            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }


    }

    private static void usage() {
        System.out.println("Syntaxe: java Serveur [numéro de port]");

    }



}


package serveur_mt;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.net.Socket;

public class Service extends Thread{

    private Socket socket;
    private BufferedReader sin;
    private PrintStream sout;


    public Service(Socket client) {
        socket=client;
        try {
         sin = new
                BufferedReader(new
                InputStreamReader(socket.getInputStream()));
         sout = new PrintStream(socket.getOutputStream());
       //début du traitement du client
         while(true) {
            String message=sin.readLine();
            if(message==""){
                break;
            }
            String reponse=inversion(message);
            sout.println(reponse);
         }



        }catch(IOException ioe) {

        }
        finally {

                try {
                    sin.close();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                sout.close();
        }
    }

    @Override
    public void run() {

        super.run();
    }

static String inversion(String str) {

        return "123456789";
    }

}