If you’ve just started using JBoss, this question should have nagged you to search in google.
It’s simple. If you generally deploy mywebapp.war in JBOSS_HOME/server/default/deploy/ (or deploy directory in all/ or minimal/) to get your app working, just do this to deploy it as an exploded archive: Unzip it, rename the directory ‘mywebapp’ to mywebapp.war and deploy it instead of war file. That’s it! It works with JBoss 4.2.2 GA and hopefully should work in the recent versions too.