Trabalhar com bytes alguem sabe?

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		System.out.println("teste");
		boolean isMultiPart = ServletFileUpload.isMultipartContent(request);
		if (isMultiPart) {
			FileItemFactory factory = new DiskFileItemFactory();
			ServletFileUpload upload = new ServletFileUpload(factory);
			try {
				List items = upload.parseRequest(request);
				Iterator iter = items.iterator();
				while (iter.hasNext()) {
					FileItem fileItem = (FileItem) iter.next();
					if (!fileItem.isFormField()) {
						if (fileItem.getName().length() > 0) {
							fileItem.getInputStream();
							System.out.println("kkkkkkkkkkkkkkkk");
							salvarComJdbc(fileItem);						
						}
					}

				}
			} 
			catch (FileUploadException ex) {
				ex.printStackTrace();
			} 
			catch (Exception ex) {
				ex.printStackTrace();
			}
		}
	}

	public void salvarComHibernate(FileItem fileItem){
		Session sessao = HibernateUtil.getSessionFactory().getCurrentSession();
		sessao.beginTransaction();
		br.com.jdevelopers.model.Arquivo arquivo = new br.com.jdevelopers.model.Arquivo(); 
		try {
			arquivo.setArquivo(Hibernate.createBlob( fileItem.get()));
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		arquivo.setMimeArquivo(fileItem.getContentType());
		arquivo.setNomeArquivo(fileItem.getName());
		sessao.save(arquivo);
		sessao.getTransaction().commit();
	}

	public void salvarComJdbc(FileItem fileItem){
		Connection conn = new ConectaBanco().canecta();
		PreparedStatement ps = null;
		System.out.println("teste0");
		try {
			ps = conn.prepareStatement("insert into arquivo values (null, ?, ?, ?)",PreparedStatement.RETURN_GENERATED_KEYS);
			try {
				System.out.println("teste1");
				ps.setBinaryStream(1, byteToInputStream(fileItem.get()),fileItem.get().length);
				System.out.println("teste2");
			} catch (Exception e) {
				// TODO Auto-generated catch block
				System.out.println("teste3..: " + e);
				e.printStackTrace();
			}
			ps.setString(2,fileItem.getContentType());
			ps.setString(3,fileItem.getName());
			ps.execute();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	public static InputStream byteToInputStream(byte[] bytes)throws Exception{ 
		ByteArrayInputStream bais = new ByteArrayInputStream (bytes); 
		return bais; 
	}

	public void salvarEmDisco(FileItem fileItem){
		FileOutputStream fis = null;
		try {
			fis = new FileOutputStream("C:/"+fileItem.getName());
			fis.write(fileItem.get());
		} catch (FileNotFoundException e1) {
			e1.printStackTrace();
		}catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}