Please have a look at How to capture SOAP messages from a Tomcat Java app to an external server? for information on setting the proxy for Tomcat.
The correct JVM parameters should look like: -Dhttps.proxyHost=127.0.0.1 -Dhttps.proxyPort=8888 -DproxySet=true -DproxyHost=127.0.0.1 -DproxyPort=8888