How to Generate an ELContext without an active FacesContext?

Question

I need to get access to EL functionality in a Servlet Filter, but... that means I am not within the FacesServlet lifecycle.

Thus, I need to instantiate an ELContext. I do not want to go down the road of instantiating a FacesContext, since that may cause issues when the application does forward to FacesServlet.

Suggestions? Thanks!

Answer 1

Better use a PhaseListener instead of a Filter.

Answer 2

I'm not sure it makes sense to do this. Within a JSP context, you would be able to resolve JSP artefacts; within a JSF context, you would be able to resolve JSF artefacts. In a Filter, these artefacts are not going to be available to you.

If you just want to resolve expressions against objects you define, it is possible to create your own context (you may need to know the platform's ExpressionFactory class if you also want to create expressions).

There is probably a better way to achieve whatever it is you are doing, such as BalusC's suggestion of a PhaseListener.

Answer 3

Since I am writing a web-framework, there is no way to use a PhaseListener, this must be done inside the Servlet Filter.

However, I did find the solution in the Seam Solder (WeldX) CDI module - this only works when running on CDI.

http://docs.jboss.org/weld/extensions/reference/latest/en-US/html/elextensions.html