Tomcat, Spring Web MVC, and Exceptions
I've been doing some server side development lately and using Spring 2.5.5 with Tomcat 6.0.18. One of the features built in is intelligent exception handling through implementations of HandlerExceptionResolver. In particular there is easy support to "fix" the HTTP response code for errors to be 200 so that Flash doesn't croak. I got my configuration setup but no matter what I did I kept getting back the default Tomcat 500 error page. A little code tracing showed that my configuration was valid and my Velocity based error page was getting picked up and processed but not reflected in the response. Turns out that Spring 2.5.5 and Tomcat 6.0.18 (and earlier versions) don't play well together. A bug has been logged against Spring so that if it generates an error response it clears out the Servlet error request attributes that Tomcat examines to determine if it should return its own built in error page. Alas as of today you'll have to grab a nightly snapshot of Spring to pickup the fix or manually patch DispatcherServlet.java.