MTEchoServer

import java.net.*;
import java.io.*;

public class MTEchoServer {
    public static void main(String[] args) throws IOException {

        int port = 9999;
        ServerSocket serverSocket = null;
        Socket clientSocket = null;
    EchoSlave slave = null;

        try {
            serverSocket = new ServerSocket(port);
        } catch (IOException e) {
            System.err.println("Could not listen on port: " + port + ".");
            System.exit(1);
        }

    try {
        while (true) {
        try {
            clientSocket = serverSocket.accept();
        } catch (IOException e) {
            System.err.println("Accept failed.");
            System.exit(1);
        }

        slave = new EchoSlave (clientSocket);
        slave.start ();
        }
    } finally {
        serverSocket.close();
    }
    }
}

class EchoSlave extends Thread {

    Socket clientSocket = null;

    public EchoSlave (Socket clientSocket) {
    this.clientSocket = clientSocket;
    }
    //gives this thread a new port so the server can still listen on the original port

    public void run () {
    OutputStream cout = null;
    InputStream cin = null;
    int aByte;

    try {
        cout = clientSocket.getOutputStream();
        cin = clientSocket.getInputStream();
        while ((aByte = cin.read()) >= 0)
        {
            cout.write (aByte);
        }
    } catch (IOException e) {
    } finally {
        try {
        cin.close();
        cout.close();
        clientSocket.close();
        } catch (IOException e) { }
    }
    }

}