JBoss4.2.3 did you add this part to jboss-web.xml file? <loader-repository> test.classloader:loader=ear1.ear <loader-repository-config>java2ParentDelegation=false</loader-repository-config> </loader-repository> And I found that test.jsp will use the A.jar that is in the application that is deployed firstly. in this case, war2 will be deployed before ear1.ear, so it use a.class in war2.war. if I modify the file org.jboss.deployment.MainDeployer-xmbean.xml in D:\jboss-4.2.3\server\default\conf\xmdesc, ==> we let jboss deploy ear file firstly, then test.jsp will use a.class that is in the ear1.ear\war1.war\WEB-INF\A.jar View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4171179#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...