Web applications can
sometimes show a number of errors that you don't
want users to see. If a user who expects to be served an
information-rich page is instead greeted with an ugly and
incomprehensible announcement of an "HTTP Status
500" in her web browser, you can bet this visit to
the site will be her last! All web sites handle unexpected
codes (such as the "404 Not Found"
or "403 Forbidden") with a friendly
and informative error message, but you'll want to
hide these messages from your users. Tools to handle both Java
runtime exceptions and these unanticipated HTTP status codes are
available to developers, and the recipes in this chapter show you how
to use them effectively.