A web server is not a file server. What happens when you "request a directory" via HTTP is totally unlike what happens when you use a File I/O call to list a directory.
In Tomcat, if you make a URL request that doesn't match any of the servlet URL patterns in the web.xml file for that particular web application context, the URL request - and the URL - are passed to Tomcat's Default Servlet, which is built into Tomcat itself. This servlet first attempts to match the URL against a JSP, and if that doesn't work, determines if the tail-end of the URL matches a relative resource path within the application WAR. If so, then the Default Servlet determines whether this resource is a data resource ("file") or a container resource ("directory"). I'm using the names in quotes because an actual WAR is not a filesystem directory, it's a ZIP file and the server's filesystem cannot read ZIP members directly, but Tomcat can.
In the case of a "directory" resource, there's logic in the Default Servlet that constructs an HTTP page, enumerates the members of that "directory", and formats the enumeration in tabular format, giving a "directory listing" in the client's view (browser).
In order to override that behavior, you are going to have to create the equivalent of the Default Servlet, map it to a suitable URL path(s) and handle those URLs in whatever format you prefer.
"privilege" comes from the Latin words for "private" and "law" (legal) and dates to feudal times. To "claim privilege" meant that you were above the laws that applied to the common people.
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Building a Better World in your Backyard by Paul Wheaton and Shawn Klassen-Koop