JavaServer Pages, 3rd Edition

Using a Common JSP Error Page

Before we end the exploration of the combination of JSP and servlets, I’d like to give you one more useful tip, namely how to use a JSP error page that displays a user-friendly error page for all runtime errors, no matter if they originate in a JSP page, a servlet, or a filter.

In Chapter 9, I showed you how to use the page directive’s errorPage attribute to specify a JSP page that is invoked in case an exception is thrown while processing the page. I also mentioned that an alternative is to declare an error page in the deployment descriptor (the WEB-INF/web.xml file). It’s then used for exceptions thrown by a servlet, a filter, or a JSP page that doesn’t declare an error page:

<error-page>
  <exception-type>java.lang.Throwable</exception-type>
  <location>/errorpage.jsp</location>
</error-page>

To recap, the <exception-type> element contains the fully qualified name of the type of exception you want to handle with the servlet, JSP page, or static page specified by the <location> element. The <location> value must be a context-relative path (starting with a slash). You can use multiple <error-page> elements to use different pages for different exceptions, and the container picks the one with the <exception-type> element that most closely matches the type of the exception thrown.

You can also define a custom handler for response status codes other than 200 (i.e., status codes that signal some kind of problem):

<error-page> <error-code>404</error-code> <location>/notfound.jsp</location> ...