JavaServer Pages, 3rd Edition

Declaring a File as a JSP Page

If a request matches a URL pattern defined within any <jsp-property-group> element, it’s implicitly defined to be a JSP page, i.e., a file the JSP container must process. A potential use for this feature is to define additional extensions that should be treated as JSP pages:

<web-app ...>
  ...
  <jsp-config>
    <jsp-property-group>
      <url-pattern>*.html</url-pattern>
    </jsp-property-grop>
  </jsp-config>
  ...
</web-app>

A deployment descriptor like this tells the container to process all requests with an .html extension as JSP pages; this might be used to add a piece of dynamic content to a previously static web site without having to rename all files.