Servlet URL pattern case sensitivity

Question

I have the following code

@WebFilter(urlPatterns = "/path/to/directory/*")
public class PageFilter extends MyBaseFilter {
}

It works as expected if I do "http://localhost/path/to/directory", but if I do http://localhost/PATH/to/directory" or any other combination the filter does not work. It appears to be case sensitive. Is there a way to make this case insensitive so it matches any permutation of the url?

• Nikos Paraskevopoulos: Servlet paths are generally case-sensitive, so this should be expected. And it should not harm since, if a web resource listens to /path, it should not respond to /PATH unless specifically configured to do so. That said, I have seen in the past cases where a servlet container deployed on a case-insensitive file system (read: Windows), would accept case-insensitive URIs for the resources that exist in the file system. If you really want a case insensitive filter, catch the root path and decide programmatically whether to apply the filter logic or not. No JEE-native way.

Answer 1

Is there a way to make this case insensitive so it matches any permutation of the url?

No.

But you can add another filter which sends a 301 (Permanent) redirect to a lowercased URI when the URI contains an uppercased character.

E.g.

@WebFilter("/*")
public class LowerCasedUriFilter extends HttpFilter {
 @Override
 public void doFilter(HttpServletRequest request, HttpServletResponse response, FilterChain chain) throws ServletException, IOException {
 var uri = request.getRequestURI();
 var lowerCasedUri = uri.toLowerCase();
 if (uri.equals(lowerCasedUri)) {
 chain.doFilter(request, response);
 }
 else {
 response.setStatus(HttpServletResponse.SC_MOVED_PERMANENTLY);
 response.setHeader("Location", lowerCasedUri);
 }
 }
}

Make sure this filter is registered before yours.