Question

For exceptions thrown while handling a request, Spring has a number of different ways to register exception handlers. Is there a way to apply similar exception handling when the exception is thrown while rendering a view? At a minimum I’d like the ability to perform some logging.

Answer 1

The problem is that exceptions thrown during View rendering cannot do an awful lot. In particular, they typically can’t render a HTML page containing an error report … or even send a 5xx response … because the response will typically have “committed” before the exception is thrown.

So the best you can do (probably) is:

• create a wrapper for the View object that catches and logs the exception, or
• do the logging in a servlet filter,

But the chances are that the web container can be configured to log uncaught exceptions anyway.

UPDATES

I just noticed spring’s HandlerInterceptor class exposes an ‘afterCompletion’ method which will be invoked when exceptions are thrown. Any thoughts as to the benefits of using this vs. a filter?

Try it and see. 🙂 But given the following, I doubt that it will work.

Using a filter or interceptor does not work for exceptions thrown while rendering a jsp. It does print to err out:

Dec 16, 2012 12:18:03 PM org.apache.catalina.core.ApplicationDispatcher 
    invoke SEVERE: Servlet.service() for servlet jsp threw exception
    javax.el.PropertyNotFoundException: Property 'fooo' not found on 
    type java.lang.String" 

Unfortunately the exception is not propagated upwards to the filter. I’d like to add my own logging which sends out error notifications and logs additional information about the failed request. Keeping an eye on log files to spot errors isn’t a good option.

1. The chances are that the log message is actually produced using the logging subsystem. If it is, you can use the logging configuration to add your own handler for JSP engine logging events and send out special notifications.

2. The fact that the exceptions are 1) being thrown during JSP view rendering, and 2) the JSP engine is not propagating them means that (IMO) it is unlikely there is a way for you to catch them.

3. The other option is to set up a scanner for the log files … as part of your general system monitoring.