ZK + Hibernate + MySQL + ClassDAO

package ClasesDominio;
public class Cargo {
 
	     private Double idCargo;
	     private String descripcion;
	     
	     public Cargo() {
		}
	     
		//SETTERS
         public void setIdCargo(Double idCargo) {
	         this.idCargo = idCargo;
	     }
         public void setDescripcion(String descripcion) {
	         this.descripcion = descripcion;
         }
	     //GETTERS
         public Double getIdCargo() {
    	             return idCargo;
    	     }
         public String getDescripcion() {
	         return descripcion;
	     }
}

package ClasesDAO;
import java.util.List;
import org.hibernate.Session;
import org.zkoss.zkplus.hibernate.HibernateUtil;

public class CargoDAO {

    Session currentSession() {
        return HibernateUtil.currentSession();
    }
  
    public void guardar(ClasesDominio.Cargo unCargo, String descripcion) {
        Session sess =  currentSession();
        unCargo.setDescripcion(descripcion);
        sess.saveOrUpdate(unCargo);
    }
    public void eliminar(ClasesDominio.Cargo unCargo) {
        Session sess =  currentSession();
        sess.delete(unCargo);
    }
    public ClasesDominio.Cargo buscar(Double idCargo) {
        Session sess =  currentSession();
        return (ClasesDominio.Cargo) sess.load(ClasesDominio.Cargo.class, idCargo);
    }
    @SuppressWarnings("unchecked")
	public List buscarTodo() {
        Session sess =  currentSession();
        return sess.createQuery("from Cargo").list();
    }
}

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
	"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
	"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
	
<hibernate-mapping>

  <class name="ClasesDominio.Cargo" table="mm_Cargo">
  	<id name="idCargo" column="PK_IdCargo">
  		<generator class="increment"/>
  	</id>
  		<property name="descripcion" type="String" column="descripcion" length="50"></property>  
  </class>
</hibernate-mapping>

<?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>
    
     <!-- Configuración de conexión a la Base de Datos -->
        <property name="connection.driver_class">org.gjt.mm.mysql.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost:3306/PortalWeb</property>
        <property name="connection.username">root</property>
        <property name="connection.password">root</property>
        <property name="dialect">org.hibernate.dialect.MySQLInnoDBDialect</property>
        
     <!-- JDBC connection pool (use the built-in) -->
        <property name="connection.pool_size">1</property>
     <!-- Enable Hibernate's automatic session context management -->
        <property name="current_session_context_class">thread</property>
     <!-- Drop and re-create the database schema on startup -->
        <property name="hbm2ddl.auto">create</property>
     <!-- Disable the second-level cache  -->
        <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
		<property name="transaction.factory_class">net.sf.hibernate.transaction.JDBCTransactionFactory</property> 
    	<property name="show_sql">true</property> 
	    <property name="use_outer_join">true</property>
	
     <!-- Mapping files --> 
		
		<mapping resource="Configuracion/Cargo.hbm.xml" />

    </session-factory>
</hibernate-configuration>

<?page title="Registro de Cargo" contentType="text/html;charset=UTF-8"?>
<zk>
<zscript><![CDATA[
import ClasesDAO.CargoDAO;
//fetch all allEvents from database
	List allCargos = new ClasesDAO.CargoDAO().buscarTodo();
]]></zscript>
<separator height="20px"/>
<grid width="600px" height="50px" visible="true" align="center" tooltiptext="Grid">
	<columns>
		<column width="100%" valign="top"/>
	</columns>
	<rows>
		<row>
			<hbox>
				<label value="Descripción " style="font-size:15px;font-weight:bold;color:darkblue;"/>
				<space width="25px"/><textbox id="txtDescripcion" width="450px"/>
			</hbox>
		</row>
	</rows>
</grid>
<space/>
<div align="center" width="600px" tooltiptext="Div">
	<button image="/Imagenes/grabar.png" id="btnGuardar" tooltiptext="Guardar"/>
	<button image="/Imagenes/eliminar.png" id="btnEliminar" tooltiptext="Eliminar"/>
	<button image="/Imagenes/cancelar.png" id="btnCancelar" tooltiptext="Cancelar"/>
	<button image="/Imagenes/salir.png" id="btnSalir" tooltiptext="Salir"/>
</div>
</zk>