以下是什么原因?给出解决方法。
log4j:WARN No appenders could be found for logger (org.springframework.context.support.FileSystemXmlApplicationContext).
log4j:WARN Please initialize the log4j system properly.
Exception in thread "main" org.springframework.orm.hibernate3.HibernateSystemException: Unknown entity: com.StudentId; nested exception is org.hibernate.MappingException: Unknown entity: com.StudentId
Caused by: org.hibernate.MappingException: Unknown entity: com.StudentId
at org.hibernate.impl.SessionFactoryImpl.getEntityPersister(SessionFactoryImpl.java:514)
at org.hibernate.impl.SessionImpl.getEntityPersister(SessionImpl.java:1302)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:89)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:186)
at org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:33)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:175)
at org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:27)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:70)
at org.hibernate.impl.SessionImpl.fireSave(SessionImpl.java:530)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:518)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:514)
at org.springframework.orm.hibernate3.HibernateTemplate$12.doInHibernate(HibernateTemplate.java:635)
at org.springframework.orm.hibernate3.HibernateTemplate.execute(HibernateTemplate.java:372)
at org.springframework.orm.hibernate3.HibernateTemplate.save(HibernateTemplate.java:632)
at com.UserDao.save(UserDao.java:19)
at com.UserDao.main(UserDao.java:30)
log4j:WARN No appenders could be found for logger (org.springframework.context.support.FileSystemXmlApplicationContext).
log4j:WARN Please initialize the log4j system properly.
Exception in thread "main" org.springframework.orm.hibernate3.HibernateSystemException: Unknown entity: com.StudentId; nested exception is org.hibernate.MappingException: Unknown entity: com.StudentId
Caused by: org.hibernate.MappingException: Unknown entity: com.StudentId
at org.hibernate.impl.SessionFactoryImpl.getEntityPersister(SessionFactoryImpl.java:514)
at org.hibernate.impl.SessionImpl.getEntityPersister(SessionImpl.java:1302)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:89)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:186)
at org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:33)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:175)
at org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:27)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:70)
at org.hibernate.impl.SessionImpl.fireSave(SessionImpl.java:530)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:518)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:514)
at org.springframework.orm.hibernate3.HibernateTemplate$12.doInHibernate(HibernateTemplate.java:635)
at org.springframework.orm.hibernate3.HibernateTemplate.execute(HibernateTemplate.java:372)
at org.springframework.orm.hibernate3.HibernateTemplate.save(HibernateTemplate.java:632)
at com.UserDao.save(UserDao.java:19)
at com.UserDao.main(UserDao.java:30)
log4j:WARN Please initialize the log4j system properly
上面这个是缺少log4j的jar包..不会影响程序的运行.下面的错可能是你没有数据库表和实体类之间的映射文件(StudentId.hbm.xml),如果有的话就是写错了,顺便问一句,你是不是用hql去操作数据库了??????