Object 타입 클래스 -> byte[] 변환 함수

public byte[] getBytes(Object obj) throws java.io.IOException{
       ByteArrayOutputStream bos = new ByteArrayOutputStream();
       ObjectOutputStream oos = new ObjectOutputStream(bos);
       oos.writeObject(obj);
       oos.flush();
       oos.close();
       bos.close();
       byte [] data = bos.toByteArray();
       return data;
   }

참고하세요...^^