[Hibernate] Could not initialize class HibernateUtil / org.slf4j.LoggerFactory not found

출처: http://liferay-portlets.blogspot.com/2009/03/problem-could-not-initialize-class.html  

Could not initialize class HibernateUtil / org.slf4j.LoggerFactory not found

 www.slf4j.org 

여기에 가서 최신 버전의

slf4-api-1.5.6.jar
slf4-simple-1.5.6.jar

를 다운받아서 classpath에 추가해준다.