I'm using Glassfish 3.1.2.2 and JSF Mojarra 2.1.6.
I have the following Facelets page:
<h:form>
<h:commandLink value="link">
<f:actionListener binding="#{backingBean.someMethod(1)}"/>
</h:commandLink>
</h:form>
And the following backing-bean:
@RequestScoped
@ManagedBean
public class BackingBean {
public void someMethod(int i) {
System.out.println("It was called: " + i);
}
}
When I click the link, "Info: It was called: 1" appears in the console.
The documentation for binding
reads:
Library: http://xmlns.jcp.org/jsf/core, http://java.sun.com/jsf/core (Jsf Core)
Tag: actionListener
binding
Value binding expression that evaluates to an object that implements javax.faces.event.ActionListener. [emphasis mine]
Also, the accepted answer to this question states that it's not possible for an f:actionListener
to call an arbitrary method.
Why is the backing bean method called if this isn't supported?
This is the consequence of the new EL 2.2 feature of calling a method in a value expression via the
#{bean.method()}
syntax instead of only referencing a property via the#{bean.property}
syntax (which should indeed be of the exact typeActionListener
). It wouldn't have worked in EL 2.1 or older and it would also not work when you remove the arguments and the parentheses. That document was written when EL 2.2 didn't exist (it's actually not modified as compared to JSF 1.2 version from May 2006; EL 2.2 was introduced December 2009). I however do agree that it needs an update on that part as it's confusing to starters.The answer you found made its points based on the document, but the answerer however didn't seem to realize based on the question that while
binding="#{testController.nodeListener}"
failed, thebinding="#{testController.nodeListener(event)}"
actually worked. This only doesn't give you the opportunity to pass theActionEvent
. The answer was better if it suggested to just usebinding="#{testController.nodeListener()}"
instead and grab the event information in other way, such as by callingUIComponent#getCurrentComponent()
or even by passing#{component}
as argument. Only if you really need to have a hand of it, of course.See also: