Question

创建java桌面数据库应用程序出错

按照官网的讲解一步步做的，数据库可以连接，但是程序运行的时候会报错，官网地址是http://netbeans.org/kb/docs/java/gui-db_zh_CN.html，报错的内容如下：
2011-4-17 13:33:22 org.jdesktop.application.Application$1 run
严重: Application class carsapp.CarsApp failed to launch
javax.persistence.PersistenceException: No Persistence provider for EntityManager named WebExtractPU: The following providers:
oracle.toplink.essentials.PersistenceProvider
oracle.toplink.essentials.ejb.cmp3.EntityManagerFactoryProvider
Returned null to createEntityManagerFactory.

at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:154)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:83)
at carsapp.CarsView.initComponents(CarsView.java:289)
at carsapp.CarsView.<init>(CarsView.java:36)
at carsapp.CarsApp.startup(CarsApp.java:19)
at org.jdesktop.application.Application$1.run(Application.java:171)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
Exception in thread "AWT-EventQueue-0" java.lang.Error: Application class carsapp.CarsApp failed to launch
at org.jdesktop.application.Application$1.run(Application.java:177)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
Caused by: javax.persistence.PersistenceException: No Persistence provider for

Answer 1

缺少这个WebExtractPU对象 ，也有可能这个类没有实现Serializable接口