TestClient.java
<code java>
package kr.appcreator.client;

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

import kr.appcreator.net.PacketMaker;

public class TestClient {
	
	public static void main(String args[]){
		
	
		PacketMaker packet= new PacketMaker();
		packet.setCommand(1000);
		packet.putString("재밋는 프로그래밍 시그");
		
		byte[] data= packet.build();
		System.out.println("send Data: " + data.length);
		int port= 7787;
		
		TestClient t= new TestClient();
		t.send( data, port );
		
	}

	private void send(byte[] data, int port) {
		
		Socket s;
		try {
			s = new Socket("210.118.73.202", port);
			
			OutputStream out= s.getOutputStream();
			out.write(data);
			
			s.close();
			try {
				Thread.sleep(1000);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
			
		} catch (UnknownHostException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

</code>

PacketMaker.java
<code java>
package kr.appcreator.net;

public class PacketMaker {

	private static final int INIT_POSITION = 4;

	private int command_;
	
	private byte[] buffer_= new byte[1024];

	private int position_= INIT_POSITION;
	
	public PacketMaker(byte[] readData) {
		position_= INIT_POSITION;
		buffer_= readData;
	}

	public PacketMaker() {
		position_= INIT_POSITION;
	}

	public void setCommand(int command) {
		
		// something code..
	}

	public void putString(String string) {
		
		// something code..
		
	}

	public byte[] build() {

		byte[] resultData= new byte[position_];
		
		// something code .. or new code?
		
		return resultData;
	}

	public int getCommand() {

                // something code .. or new code ?

		return 0;
	}

	public String getString() {
		
		
                 return null;
	}

	public void putInt(int value) {

		buffer_[position_++]= (byte)((value >> 24) & 0xFF);		
		buffer_[position_++]= (byte)((value >> 16) & 0xFF);
		buffer_[position_++]= (byte)((value >> 8) & 0xFF);
		buffer_[position_++]= (byte)(value & 0xFF);
	}

	public int getInt() {
	
		int value= (get() << 24 & 0xFF000000);
		value = value | ((get() << 16) & 0x00FF0000);
		value = value | ((get() << 8) & 0x0000FF00);
		value = value | (get() & 0x000000FF);
		
		return value;
	}

	private int get() {
                 // something code ..
		return 0;
	}
	
	private void put(byte data) {
		// something code..
	}

}
</code>