<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- Generated 24-oct-2006 10:13:50 by Hibernate Tools 3.2.0.beta8 -->
<hibernate-mapping>
    <class name="com.gmsoft.model.Role" table="ROLE">
        <id name="codi" type="int">
            <column name="CODI" precision="38" scale="0" />
            <generator class="assigned" />
        </id>
        <property name="descripcio" type="string">
            <column name="DESCRIPCIO" length="32" not-null="true" />
        </property>
        <set name="clients" inverse="true">
            <key>
                <column name="ROL" precision="38" scale="0" not-null="true" />
            </key>
            <one-to-many class="com.gmsoft.model.Client" />
        </set>
    </class>
</hibernate-mapping>

package com.gmsoft.model;

// Generated 24-oct-2006 10:13:50 by Hibernate Tools 3.2.0.beta8

import java.util.HashSet;
import java.util.Set;

/**
* Role generated by hbm2java
*/
public class Role implements java.io.Serializable {

   // Fields   

   private int codi;

   private String descripcio;

   private Set<Client> clients = new HashSet<Client>(0);

   // Constructors

   /** default constructor */
   public Role() {
   }

   /** minimal constructor */
   public Role(int codi, String descripcio) {
      this.codi = codi;
      this.descripcio = descripcio;
   }

   /** full constructor */
   public Role(int codi, String descripcio, Set<Client> clients) {
      this.codi = codi;
      this.descripcio = descripcio;
      this.clients = clients;
   }

   // Property accessors
   public int getCodi() {
      return this.codi;
   }

   public void setCodi(int codi) {
      this.codi = codi;
   }

   public String getDescripcio() {
      return this.descripcio;
   }

   public void setDescripcio(String descripcio) {
      this.descripcio = descripcio;
   }

   public Set<Client> getClients() {
      return this.clients;
   }

   public void setClients(Set<Client> clients) {
      this.clients = clients;
   }

}

public class RoleDAO {

...

   public void persist(Role transientInstance) {
      log.debug("persisting Role instance");
      try {
         org.hibernate.Session s = HibernateUtil.currentSession();
         s.save(transientInstance);
         s.flush();   <<---------------

         log.debug("persist successful");
      } catch (RuntimeException re) {
         log.error("persist failed", re);
         throw re;
      }
...
   }

public class HibernateUtil {

    private static Log log = LogFactory.getLog(HibernateUtil.class);

    private static final SessionFactory sessionFactory;

    static {
        try {
            // Create the SessionFactory
            sessionFactory = new Configuration().configure("./webshop/WEB-INF/classes/hibernate.cfg.xml").buildSessionFactory();
        } catch (Throwable ex) {
            log.error("Initial SessionFactory creation failed.", ex);
            throw new ExceptionInInitializerError(ex);
        }
    }

    public static final ThreadLocal session = new ThreadLocal();

    public static Session currentSession() throws HibernateException {
        Session s = (Session) session.get();
        // Open a new Session, if this Thread has none yet
        if (s == null) {
            s = sessionFactory.openSession();
            session.set(s);
        }
        return s;
    }

    public static void closeSession() throws HibernateException {
        Session s = (Session) session.get();
        session.set(null);
        if (s != null)
            s.close();
    }
}

<?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 name="GeneralSessionFactory">
        <property name="hibernate.bytecode.use_reflection_optimizer">false</property>
        <property name="hibernate.connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
        <property name="hibernate.connection.password">password</property>
        <property name="hibernate.connection.url">jdbc:oracle:thin:@192.168.1.2:1500:webshop</property>
        <property name="hibernate.connection.username">user</property>
        <property name="hibernate.default_schema">APP</property>
        <property name="hibernate.dialect">org.hibernate.dialect.OracleDialect</property>
        <mapping resource="com/gmsoft/model/Role.hbm.xml" />
        <mapping resource="com/gmsoft/model/Client.hbm.xml" />
    </session-factory>
</hibernate-configuration>

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
      try {
         response.getWriter().println("Intentant guardar role...");
         com.gmsoft.model.Role rol = new Role();
         rol.setCodi(60);
         rol.setDescripcio("Hibernate");
         com.gmsoft.model.RoleHome roleDAO = new RoleHome();
         roleDAO.persist(rol);
         response.getWriter().println("Role guardat flush!!!");
      }catch (Exception ex) {
         response.getWriter().println(ex.getMessage());
         ex.printStackTrace(response.getWriter());
      }
   }