Are you deploying a war file or a folder of your project.Deploying folders is generally not recommended esp for non static projects.Hot deployments are the way to go.You could also explore JRebel
There was a bug in 7.1.1.Final which caused this problem for JSPs. You'll have to use a recently released version instead.
Finally I have found the solution:
1. Please make sure to add
in standalone.xml under <subsystem xmlns="urn:jboss:domain:web:1.1" default-virtual-server="default-host" native="false">
2. Go to jboss-as-7.1.1.Final/modules/org/jboss/as/web/main
Place the jboss-as-web-7.1.1.Final-RECOMPILE.jar in there. You can download from http://www.datafilehost.com/download-2cb9ff04.html
3. Open module.xml (jboss-as-7.1.1.Final/modules/org/jboss/as/web/main) and add the following line
Thanks to all for the help.