the real problem is
JBoss can't find the common jar
There are two way to fix
1.copy all the common*.jar and struts.jar to
if any classloader exception appear again,
check the lib depedn on struts all copy to server/lib
2.change the jboss config
add classpath finder to your webapps directory..
But I haven't successed!
it is a class not found problem
If you put all the lib on your webapps/lib
JBoss still not to load it
You have to put all the jar(struts.jar common*.jar etc)
to the catalina_home/server/lib
I don't know why..
But it works for me..