Erro ao acessar banco via Hibernate ...Erro ao conectar ao banco de dados...java.lang.NoClassDefFoun

278 [main] INFO org.hibernate.annotations.common.Version - Hibernate Commons Annotations 3.2.0.Final
293 [main] INFO org.hibernate.cfg.Environment - Hibernate 3.6.0.Final
297 [main] INFO org.hibernate.cfg.Environment - hibernate.properties not found
304 [main] INFO org.hibernate.cfg.Environment - Bytecode provider name : javassist
313 [main] INFO org.hibernate.cfg.Environment - using JDK 1.4 java.sql.Timestamp handling
464 [main] INFO org.hibernate.cfg.Configuration - configuring from resource: hibernate.cfg.xml
464 [main] INFO org.hibernate.cfg.Configuration - Configuration resource: hibernate.cfg.xml
586 [main] WARN org.hibernate.util.DTDEntityResolver - recognized obsolete hibernate namespace http://hibernate.sourceforge.net/. Use namespace http://www.hibernate.org/dtd/ instead. Refer to Hibernate 3.6 Migration Guide!
644 [main] INFO org.hibernate.cfg.Configuration - Configured SessionFactory: null
Erro ao conectar ao banco de dados...javax/persistence/EntityListeners
Erro ao conectar ao banco de dados...java.lang.NoClassDefFoundError: javax/persistence/EntityListeners
Exception in thread "main" java.lang.NullPointerException
	at com.livro.capitulo3.conexao.ConectaHibernateMysql.main(ConectaHibernateMysql.java:20)

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
	<session-factory>
		<!--Database connection setting -->
		<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
		<property name="connection.url">jdbc:mysql://127.0.0.1/agenda</property>
		<property name="connection.username">root</property>
		<property name="connection.password">paulo</property>
		
		<!--JDBC connection pool(use built-in)-->
		<property name="connection.pool_size">1</property>
		<!--SQL dialect -->
		<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
		<!-- Enable Hibernate's automatic session context management -->
		<property name="current_session_context_class">thread</property>
		<!-- Disable the second-level cache -->
		<property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
		<!-- Echo all execute SQL to stdout-->
		<property name="show_sql">false</property>
	</session-factory>
</hibernate-configuration>

import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.exception.Configurable;

public class HibernateUtil {

	private static final SessionFactory sessionFactory = buildSessionFactory();
	private static SessionFactory buildSessionFactory(){
		try {
			Configuration cfg = new Configuration();
			cfg.configure("hibernate.cfg.xml");
			return cfg.buildSessionFactory();
		} catch (Exception e) {
			System.out.println("Criação Inicial do objeto SessionFactory falhou .Erro :"+e);
		}
		return getSessionfactory();
	}
	
	public static SessionFactory getSessionfactory(){
		return sessionFactory;
	}
}

import org.hibernate.Session;

public class ConectaHibernateMysql {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Session sessao=null;
		try {
			 sessao=HibernateUtil.getSessionfactory().openSession();
			 System.out.println("Conectou....");
		} catch (Throwable e) {
			 System.out.println("Erro ao conectar ao banco de dados..."+e.getMessage());
			 System.out.println("Erro ao conectar ao banco de dados..."+e);
		}finally{
			sessao.close();
		}

	}

}