hibernate求助,谢谢+谢谢

log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
%%%% Error Creating SessionFactory %%%%
org.hibernate.MappingException: Association references unmapped class: Account
at org.hibernate.cfg.HbmBinder.bindCollectionSecondPass(HbmBinder.java:2344)
at org.hibernate.cfg.HbmBinder.bindListSecondPass(HbmBinder.java:2195)
at org.hibernate.cfg.HbmBinder$ListSecondPass.secondPass(HbmBinder.java:2685)
at org.hibernate.cfg.CollectionSecondPass.doSecondPass(CollectionSecondPass.java:35)
at org.hibernate.cfg.Configuration.secondPassCompile(Configuration.java:1012)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1168)
at com.lovo.HibernateSessionFactory.rebuildSessionFactory(HibernateSessionFactory.java:60)
at com.lovo.HibernateSessionFactory.getSession(HibernateSessionFactory.java:43)
at com.lovo.CustomerDao.deleteAll(CustomerDao.java:8)
at com.lovo.CustomerDao.main(CustomerDao.java:22)
Exception in thread "main" java.lang.NullPointerException
at com.lovo.CustomerDao.deleteAll(CustomerDao.java:9)
at com.lovo.CustomerDao.main(CustomerDao.java:22)
运行时,出这个错误,哈哈问题在帖子忘掉了