J2EP is a reverse proxy running on a J2EE engine. The proxy is written in java and was originally designed with Tomcat in mind, but any engine should work fine. A set of basic mapping rules are included but they can easily be extended to your own needs.
jRevProxy is a lightweight reverse proxy server fully written in Java. jRevProxy accepts HTTP and HTTPS requests and translates these into new requests based on a set of rules. HTTPS with client side authentication (X509 certificates) is supported.