EDIT

package eu.etaxonomy.cdm.persistence.hibernate;

import org.apache.log4j.Logger;

import org.hibernate.HibernateException;

import org.hibernate.event.SaveOrUpdateEvent;

import org.hibernate.event.SaveOrUpdateEventListener;

import org.joda.time.DateTime;

import org.springframework.security.Authentication;

import org.springframework.security.context.SecurityContextHolder;

import eu.etaxonomy.cdm.model.common.User;

import eu.etaxonomy.cdm.model.common.VersionableEntity;

public class UpdateEntityListener implements SaveOrUpdateEventListener {

	private static final long serialVersionUID = -3295612929556041686L;

	@SuppressWarnings("unused")

	private static final Logger logger = Logger.getLogger(UpdateEntityListener.class);

	public void onSaveOrUpdate(SaveOrUpdateEvent event)

			throws HibernateException {

		Object entity = event.getObject();

		if(entity != null && VersionableEntity.class.isAssignableFrom(entity.getClass())) {

			VersionableEntity versionableEntity = (VersionableEntity)entity;

			versionableEntity.setUpdated(new DateTime());

			Authentication authentication = SecurityContextHolder.getContext().getAuthentication();

			if(authentication != null && authentication.getPrincipal() != null && authentication.getPrincipal() instanceof User) {

			  User user = (User)authentication.getPrincipal();

			  versionableEntity.setUpdatedBy(user);

			} 

		}

	}

}