Save checkbox state After ReLoadThe Page in JSF Primefaces - primefaces

Question

Im using a "DataTable - Selection",(http://www.primefaces.org/showcase/ui/data/datatable/selection.xhtml) in primefaces 5 to check the selected rows, but when I reload the page, the checkboxes are unchecked, How can i keep the state of the checkboxes in session?
**
*********DataTable****************
**
<p:dataTable var="var" value="#{vistaBean.listaFichero}" rowKey="#{var.nombre}" paginator="true" rows="10"
selection="#{vistaBean.selectFichero}">
<f:facet name="header">
Votar ProductBox
</f:facet>
<p:column headerText="Votar" selectionMode="multiple"/>
<p:column headerText="Nombre del Fichero">
<h:outputText value="#{var.nombre}" />
</p:column>
<p:column headerText="Ver/Descargar">
<h:commandLink id="pdf" action="#{vistaBean.downLoad}">
<f:setPropertyActionListener target="#{vistaBean.ruta}" value="#{var.ruta}" />
<h:graphicImage library="images" name="pdf.png" />
</h:commandLink>
</p:column>
</p:dataTable>
<p:commandButton value="Guardar Votos" action="#{vistaBean.addVoto()}" update="msgs"/>
<p:commandButton value="Ver Votos" update="display" oncomplete="PF('dlg').show()" icon="ui-icon-check" inmediate="true"/>
<p:dialog header="Product Box Seleccionados" modal="true" showEffect="clip" widgetVar="dlg" resizable="false">
<p:outputPanel id="display">
<p:dataList value="#{vistaBean.selectFichero}" var="v">
#{v.nombre}
</p:dataList>
</p:outputPanel>
</p:dialog>

Answer 1

I solve the issue by installing a newer version of Primefaces, 5.2, i had the 5.1 and it had that bug.

Answer 2

This is how you set a session variable:
FacesContext facesContext = FacesContext.getCurrentInstance();
HttpSession session = (HttpSession) facesContext.getExternalContext().getSession(true);
session.setAttribute("foo", "bar");
This is how you can get session variables:
FacesContext facesContext = FacesContext.getCurrentInstance();
HttpSession session = (HttpSession) facesContext.getExternalContext().getSession(false);
Enumeration e = session.getAttributeNames();
while (e.hasMoreElements())
{
String attr = (String)e.nextElement();
System.err.println(" attr = "+ attr);
Object value = session.getValue(attr);
System.err.println(" value = "+ value);
}
Your only task is to save the state of your checkboxes into the session and then load it.