Java Reference
In-Depth Information
when the value-change event occurs. The
ValueChangeEvent
instance stores the old
and the new values of the component that fired the event.
In the Duke's Bookstore case study, the
NameChanged
listener implementation is re-
gistered on the
name UIInput
component on the
bookcashier.xhtml
page. This
listener stores into session scope the name the user entered in the text field corresponding
to the name component.
The
bookreceipt.xhtml
subsequently retrieves the name from the session scope:
<h:outputFormat title="thanks"
value="#{bundle.ThankYouParam}">
<f:param value="#{sessionScope.name}"/>
</h:outputFormat>
When the
bookreceipt.xhtml
page is loaded, it displays the name inside the mes-
sage:
"Thank you, {0}, for purchasing your books from us."
Here is part of the
NameChanged
listener implementation:
public class NameChanged extends Object implements
ValueChangeListener {
@Override
public void processValueChange(ValueChangeEvent event)
throws AbortProcessingException {
if (null != event.getNewValue()) {
FacesContext.getCurrentInstance().getExternalContext().
getSessionMap().put("name", event.getNewValue());
}
}
}
When the user enters the name in the text field, a value-change event is generated, and
the
processValueChange(ValueChangeEvent)
method of the
NameChanged
listener implementation is invoked. This method first gets the ID of the component that
fired the event from the
ValueChangeEvent
object, and it puts the value, along with
an attribute name, into the session map of the
FacesContext
instance.
