Untitled

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

public class TestServer {
    // We do no nice exception handling! Very bad!!!
    // But the idea is to have a very short code.
    public static void main(String[] args) throws Exception{
        // We are listening to port 4321
        ServerSocket server = new ServerSocket(4321);

        while(true){
            Socket connection = server.accept();
            ConnectionHandler connectionHandler = new ConnectionHandler(connection);
            new Thread(connectionHandler).start();
        }

    }
}

class ConnectionHandler implements Runnable{

    private Socket connection;
    private static int bufsize = 512;

    ConnectionHandler(Socket connection){
        this.connection = connection;
    }

    public void run(){
        try{
            InputStream ins = connection.getInputStream();
            OutputStream outs = connection.getOutputStream();
    
            // We will read one byte at a time.
            byte[] buffer = new byte[bufsize];
            try {
                do {
                    int bytesread = ins.read(buffer);
                    if (bytesread == -1){
                        // We have the end of the input stream.
                        // So the other side is done. We can
                        // close the connection safely
                        break;
                    }
                    String str = new String(buffer, 0, bytesread);
                    System.out.print(str);
                    outs.write(buffer,0,bytesread);
                } while (true);
            } finally {
                connection.close();
            }
        }catch(IOException e){
            e.printStackTrace();
        }
    }
}