Java GUI链接sqlserver的问题

run: Exception in thread "AWT-EventQueue-0" javax.persistence.PersistenceException: No Persistence provider for EntityManager named localhost:1433;DatabaseName=OSPU: Provider named oracle.toplink.essentials.PersistenceProvider threw unexpe... run: Exception in thread "AWT-EventQueue-0" javax.persistence.PersistenceException: No Persistence provider for EntityManager named localhost:1433;DatabaseName=OSPU: Provider named oracle.toplink.essentials.PersistenceProvider threw unexpected exception at create EntityManagerFactory: oracle.toplink.essentials.exceptions.PersistenceUnitLoadingException Local Exception Stack: ) at java.awt.EventDispatchThread.run(EventDispatchThread.java:121) Caused by: javax.persistence.PersistenceException: Exception [TOPLINK-28018] (Oracle TopLink Essentials - 2.0.1 (Build b09d-fcs (12/06/2007))): oracle.toplink.essentials.exceptions.EntityManagerSetupException Exception Description: predeploy for PersistenceUnit [localhost:1433;DatabaseName=OSPU] failed. Internal Exception: Exception [TOPLINK-30007] (Oracle TopLink Essentials - 2.0.1 (Build b09d-fcs (12/06/2007))): oracle.toplink.essentials.exceptions.PersistenceUnitLoadingException Exception Description: An exception was thrown while loading class: Base.Car to check whether it implements @Entity， @Embeddable， or @MappedSuperclass. Internal Exception: java.lang.ClassNotFoundException: Base.Car 我的sqlserver已经在Netbean成功连接了，可以在NetBeans查看到了数据库的信息。。 可是还是显示Exception Description: predeploy for PersistenceUnit [localhost:1433;DatabaseName=OSPU] failed. Z主要的是Caused by: java.lang.ClassNotFoundException: Base.Car ，这个Base.car文件已经被我删除了，怎么还显示不能生成类啊。。跪求高手解答