Tcp socket 통신

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

public class Server extends Thread {
    final static int SERVER_PORT = 1225;
    final static String MESSAGE_TO_SERVER = "Hello world!!! receive message from Client";

    public static void main(String[] args) {

        ServerSocket serverSocket = null;

        try {
            serverSocket = new ServerSocket(SERVER_PORT);


        } catch (IOException e) {
            e.printStackTrace();
        }

        try {
            while (true) {
                Socket socket = serverSocket.accept();

                /**    Server에서 보낸 값을 받기 위한 통로 */
                InputStream is = socket.getInputStream();
                /**    Server에서 Client로 보내기 위한 통로 */
                OutputStream os = socket.getOutputStream();

                byte[] data = new byte[16];
                int n = is.read(data);
                final String messageFromClient = new String(data,0,n);

                System.out.println(messageFromClient);

                os.write( MESSAGE_TO_SERVER.getBytes() );
                os.flush();

                is.close();
                os.close();
                socket.close();
            }

        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

class SocketRun implements Runnable {

    private Socket socket = null;

    SocketRun( Socket socket ){
        this.socket = socket;
    }

    @Override
    public void run() {

    }
}

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;
import java.net.UnknownHostException;

public class Client {
    private static final String SERVER_IP = "127.0.0.1";
    private static int SERVER_PORT = 1225;
    private static final String MESSAGE_TO_SERVER = "Hellow world!!! send message to Server";

    public static void main(String[] args) {
        Socket socket = null;

        try {
            socket = new Socket(SERVER_IP, SERVER_PORT);
            System.out.println("socket 연결");
            OutputStream os = socket.getOutputStream();
            InputStream is = socket.getInputStream();
            os.write(MESSAGE_TO_SERVER.getBytes());
            os.flush();

            byte[] bytes = new byte[16];
            int n = is.read(bytes);
            final String resultFromServer = new String(bytes,0,n);
            System.out.println(resultFromServer);
            socket.close();

        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch(IOException e) {
            e.printStackTrace();
        }
    }
}