The Jakarta Commons Team is pleased to announce the first official release
of Commons EL from the Apache Software Foundation. Commons EL provides
an interpreter for the Expression Language that is part of the
JavaServer Pages(TM) specification, version 2.0.
For more details see the
release notes.
Source and
binary distributions
are available from the mirrors. Please remember to verify the signatures
of the distribution using the keys found on the
main apache site
when downloading from a mirror.
For more information on Commons EL, see the
EL
web site.
Hmmm, I wonder if this means we can add EL support to the display tag library without including JSTL?
With a little prodding from Erik Hatcher today, I took another look at Struts' Declared Exceptions feature. At the end of last year, I was wishing I could use declared exceptions to do chained exceptions for my Action classes. Basically, in each of my Actions, I have a try/catch wrapped around a call to the Business Delegate (example: UserAction.java). You'll notice that all the CRUD methods have the same catch block for exception handling:
} catch (Exception e) {
e.printStackTrace();
errors.add(ActionErrors.GLOBAL_ERROR,
new ActionError("errors.general"));
while (e != null) {
errors.add(ActionErrors.GLOBAL_ERROR,
new ActionError("errors.detail", e.getMessage()));
e = (Exception) e.getCause();
}
saveErrors(request, errors);
return mapping.getInputForward();
}
After talking with Erik this morning, I decided to create an ActionExceptionHandler for java.lang.Exception. In my struts-config.xml, I added:
<exception type="java.lang.Exception" key="errors.general"
handler="org.appfuse.webapp.action.ActionExceptionHandler"/>
I have "errors.general=The process did not complete. Details should follow." Here is the code for ActionExceptionHandler:
public final class ActionExceptionHandler extends ExceptionHandler {
public ActionForward execute(Exception ex, ExceptionConfig ae,
ActionMapping mapping,
ActionForm formInstance,
HttpServletRequest request,
HttpServletResponse response)
throws ServletException {
ActionForward forward = null;
ActionError error = null;
ActionErrors errors = new ActionErrors();
String property = null;
// Build the forward from the exception mapping if it exists
// or from the form input
if (ae.getPath() != null) {
forward = new ActionForward(ae.getPath());
} else {
forward = mapping.getInputForward();
}
ex.printStackTrace();
errors.add(ActionErrors.GLOBAL_ERROR, new ActionError(error.getKey()));
while (ex != null) {
errors.add(ActionErrors.GLOBAL_ERROR,
new ActionError("errors.detail", ex.getMessage()));
ex = (Exception) ex.getCause();
}
// Store the errors and exception
request.setAttribute(Globals.ERROR_KEY, errors);
return forward;
}
}
This allows me to remove my generic try/catches from my action classes - very slick IMO (or at least better than the code smell I had)! Of course, I still have some catch blocks that catch specific exceptions, but I can either (1) leave those intact, or (2) create another declared exception for that particular action/exception. I dig it and will be adding it (in short order) to AppFuse.
Update (June 23, 2003): Here's a more thoroughly tested code sample of this same class.
