<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
    <class name="model.beans.Rooster" table="ROOSTERS" schema="PUBLIC">
        <id name="roosterId" type="java.lang.Long">
            <column name="ROOSTER_ID" />
            <generator class="assigned"></generator>
        </id>
        <property name="fieldNum" type="java.lang.Integer">
           <column name="FIELDNUM" not-null="false"></column>
        </property>
        <property name="dayNum" type="java.lang.Integer">
            <column name="DAY_NUM" not-null="true" />
        </property>
        <property name="startTime" type="java.util.Calendar">
            <column name="START_TIME" length="6" not-null="true" />
        </property>
        <property name="endTime" type="java.util.Calendar">
            <column name="END_TIME" length="6" not-null="true" />
        </property>
        <set name="matchPlannings" inverse="true">
            <key>
                <column name="FK_ROOSTERID" />
            </key>
            <one-to-many class="model.beans.MatchPlanning" />
        </set>
    </class>
</hibernate-mapping>

   public void saveOrUpdate(Rooster obj) {
      
       log.debug("saving Roosters instance");
           try {
              HibernateSessionFactory.getSession().saveOrUpdate(obj);
              System.out.println("Saving rooster with id"+obj.getRoosterId() + " ok");
               log.debug("save successful");
           } catch (RuntimeException re) {
               log.error("save failed", re);
               throw re;
           }
   }

package model.beans;

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.cfg.Configuration;

/**
* Configures and provides access to Hibernate sessions, tied to the
* current thread of execution.  Follows the Thread Local Session
* pattern, see {@link http://hibernate.org/42.html }.
*/
public class HibernateSessionFactory {

    /**
     * Location of hibernate.cfg.xml file.
     * Location should be on the classpath as Hibernate uses 
     * #resourceAsStream style lookup for its configuration file.
     * The default classpath location of the hibernate config file is
     * in the default package. Use #setConfigFile() to update
     * the location of the configuration file for the current session.   
     */
    private static String CONFIG_FILE_LOCATION = "/hibernate.cfg.xml";
   private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>();
    private  static Configuration configuration = new Configuration();
    private static org.hibernate.SessionFactory sessionFactory;
    private static String configFile = CONFIG_FILE_LOCATION;

    private HibernateSessionFactory() {
    }
   
   /**
     * Returns the ThreadLocal Session instance.  Lazy initialize
     * the <code>SessionFactory</code> if needed.
     *
     *  @return Session
     *  @throws HibernateException
     */
    public static Session getSession() throws HibernateException {
        Session session = (Session) threadLocal.get();

      if (session == null || !session.isOpen()) {
         if (sessionFactory == null) {
            rebuildSessionFactory();
         }
         session = (sessionFactory != null) ? sessionFactory.openSession()
               : null;
         threadLocal.set(session);
      }

        return session;
    }

   /**
     *  Rebuild hibernate session factory
     *
     */
   public static void rebuildSessionFactory() {
      try {
         configuration.configure(configFile);
         sessionFactory = configuration.buildSessionFactory();
      } catch (Exception e) {
         System.err
               .println("%%%% Error Creating SessionFactory %%%%");
         e.printStackTrace();
      }
   }

   /**
     *  Close the single hibernate session instance.
     *
     *  @throws HibernateException
     */
    public static void closeSession() throws HibernateException {
        Session session = (Session) threadLocal.get();
        threadLocal.set(null);

        if (session != null) {
            session.close();
        }
    }

   /**
     *  return session factory
     *
     */
   public static org.hibernate.SessionFactory getSessionFactory() {
      return sessionFactory;
   }

   /**
     *  return session factory
     *
     *   session factory will be rebuilded in the next call
     */
   public static void setConfigFile(String configFile) {
      HibernateSessionFactory.configFile = configFile;
      sessionFactory = null;
   }

   /**
     *  return hibernate configuration
     *
     */
   public static Configuration getConfiguration() {
      return configuration;
   }

}

<property name="hibernate.current_session_context_class">
      jta
   </property>

<property name="hibernate.current_session_context_class">
      org.hibernate.context.JTASessionContext
   </property>

Transaction tx = session.beginTransaction();
try {
   session.save( entity );
   session.flush();
   tx.commit();
}
catch(HibernateException e) {
   tx.rollback();
   // log || handle exception
}