Question

I am using a phase listener to manage things like logon and conversation scope. In some situations I want to redirect. The most obvious is when the user is not logged on and they are attempting to access a protected page.

Currently my PhaseListener runs After Restore View. This is sometimes too late. When the user logs off the page is disposed and they are redirected back to the logon page. That page disposal causes some AJAX events in IceFaces – only I’ve destroyed the session so beans are missing state. This causes exceptions during Restore View, which appears to access the backing bean through EL in the page.

If I move my phase listener to Before Restore View and attempt to redirect using the ExternalContext I end up with a NullPointerException.

java.lang.NullPointerException
com.sun.faces.lifecycle.RestoreViewPhase.notifyAfter(RestoreViewPhase.java:301)
com.sun.faces.lifecycle.RestoreViewPhase.doPhase(RestoreViewPhase.java:114)
com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
javax.faces.webapp.FacesServlet.service(FacesServlet.java:312)
org.jboss.weld.servlet.ConversationPropagationFilter.doFilter(ConversationPropagationFilter.java:67)
com.ocpsoft.pretty.PrettyFilter.doFilter(PrettyFilter.java:118)

One option I could use would be use use a Servlet Filter for this work. It would also cover non-JSF requests. I don’t know how much of JSF will be available (and how much I actually need) in this case and it is not immediately clear how I cam make my filter happen after things like the ConversationPropagationFilter and before PrettyFilter.

Thanks
– Richard

Answer 1

java.lang.NullPointerException
  com.sun.faces.lifecycle.RestoreViewPhase.notifyAfter(RestoreViewPhase.java:301)

That’s an old bug which is already been fixed in Mojarra 2.1 . The source of RestoreViewPhase#notifyAfter() method of for example Mojarra 2.0.2 says the following:

299  private void notifyAfter(FacesContext context, Lifecycle lifecycle) {
300      UIViewRoot viewRoot = context.getViewRoot();
301      MethodExpression afterPhase = viewRoot.getAfterPhaseListener();

which means that viewRoot is null. That can happen if FacesContext#responseComplete() is been called before that point, which in turn is implicitly done by ExternalContext#rediect(). After Mojarra 2.1, a nullcheck on viewRoot is been added which fixes this bug.

So, upgrade to at least Mojarra 2.1. It’s currently already at 2.1.4.

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As to your (unrelated) note:

One option I could use would be use use a Servlet Filter for this work. It would also cover non-JSF requests. I don’t know how much of JSF will be available (and how much I actually need) in this case and it is not immediately clear how I cam make my filter happen after things like the ConversationPropagationFilter and before PrettyFilter.

JSF stores managed beans and a lot of other information as attributes of HttpSession and ServletContext, all which are available in the Filter. So that should be doable. As to the filter invocation order; that’s just controllable by the <filter-mapping> order in web.xml.