/**
* This filter open and close HibernateTransaction
*/
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
		throws IOException, ServletException {
	Session session = HibernateSessionFactory.getSession();
	Transaction tx = null;
	try {
		logger.debug("Starting a database transaction");
		tx = session.beginTransaction();

		// Call the next filter (continue request processing)
		chain.doFilter(request, response);
		if (tx.isActive()) {
			// Commit if needed and cleanup
			logger.debug("Committing the database transaction");
			tx.commit();
		}

	} catch (Throwable ex) {
		logger.debug("failed to process the request!", ex);
		if ((tx != null) && tx.isActive())
			tx.rollback();
		if (session.isOpen())
			session.close();
		ex.printStackTrace();
	}
}

/**
 * Create if necessary, and return the singleton Hibernate SessionFactory.
 */
public static SessionFactory getSessionFactory() {
	try {
		if (sessionFactory == null) {
			// configuration settings from hibernate.cfg.xml
			Configuration configuration = new Configuration().configure(CONFIG_FILE_LOCATION);

			StandardServiceRegistryBuilder serviceRegistryBuilder = new StandardServiceRegistryBuilder();
			serviceRegistryBuilder.applySettings(configuration.getProperties());
			ServiceRegistry serviceRegistry = serviceRegistryBuilder.build();

			sessionFactory = configuration.buildSessionFactory(serviceRegistry);
		}
		return sessionFactory;
	} catch (Throwable ex) {
		System.err.println("Initial SessionFactory creation failed." + ex);
		throw new ExceptionInInitializerError(ex);
	}
}

/**
* This method use sessionFactory to get current session
*/
@Override
public T getById(PK pk) {
	T entity = (T) getSessionFactory.getSession().get(getTypeClass(), pk);
	logger.info("getById loaded successfully, Entity details=" + entity + " / PK=" + pk);
	return entity;
}

/**
*	This method get object and set a new value into property [used].
*/
@Override
public Downloader setUsedById(Long id) {
	Downloader down = getById(id);
	down.setUsed(1);
	return down;
}