java - Seam centralized exceptions -

i'm using seam 2.2, primefaces view presentation layer. write kind of infrastructure in order capture exceptions. example put in facelets following piece of code:

<p:commandbutton actionlistener="#{myseamcontroller.amethod()}" 

in myseamcontroller class, above method:

public void amethod() {     throw new nullpointerexception(); } 

in controller write method:

 @observer("myapp.exceptions.exception")  public void onsystemexception(exception e)  {     system.out.println("a exception occurred");   } 

i write class catch exceptions:

@scope(scopetype.application) @bypassinterceptors @install( precedence = install.mock, classdependencies = "javax.faces.context.facescontext") @name("org.jboss.seam.exception.exceptions") public class exceptionhandler extends org.jboss.seam.exception.exceptions{    private static final long serialversionuid = 1l;  @logger     log log;   public void handle(exception e) throws exception   {               events.instance().raiseevent("myapp.exceptions.exception", e);   super.handle(e);   } } 

but i've noticed taht when use actionlistener

<p:commandbutton actionlistener="#{myseamcontroller.amethod()}" 

instead of action

<p:commandbutton action="#{myseamcontroller.amethod()}" 

no exception observed exceptionhandler class. why? can help? best regards

create interceptor, , can catch need.