Just learnt EJB for half month. Just learnt how to create Entity class. When deploys, JBOSS always give me error. Now I found a solution, The problem is sometimes persistence.xml lost the XML Schema, the full persistence.xml can be like this:
<?xml version=”1.0″ encoding=”UTF-8″?>
<persistence
xmlns=”http://java.sun.com/xml/ns/persistence”
xmlns:xsi=”http://www.w3.org/2001/XMLSchema-instance”
xsi:schemaLocation=”http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd”
version=”1.0″>
<persistence-unit name=”calculator”>
<jta-data-source>java:/DefaultDS</jta-data-source>
<properties>
<property name=”hibernate.hbm2ddl.auto” value=”create-drop” />
</properties>
</persistence-unit>
</persistence>
Hope anyone who faced this problem can solve your problem.