org.hibernate.TransientObjectException: The given object has a null identifier；

在SSH中当对数据update的时候，主键设置自增时候。不进行管理。不对其赋所修改的值时会报如下错误。

org.hibernate.TransientObjectException: The given object has a null identifier:  

 at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.getUpdateId(DefaultSaveOrUpdateEventListener.java:249)
at org.hibernate.event.def.DefaultUpdateEventListener.getUpdateId(DefaultUpdateEventListener.java:46)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsDetached(DefaultSaveOrUpdateEventListener.java:217)
at org.hibernate.event.def.DefaultUpdateEventListener.performSaveOrUpdate(DefaultUpdateEventListener.java:33)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:70)
at org.hibernate.impl.SessionImpl.fireUpdate(SessionImpl.java:565)
at org.hibernate.impl.SessionImpl.update(SessionImpl.java:552)
at org.hibernate.impl.SessionImpl.update(SessionImpl.java:544)
at com.meeMei.daoImpl.CommodityDaoImpl.update(CommodityDaoImpl.java:87)
at com.meeMei.Behind.service.impl.BehindManageCommodityImpl.virtualUpateCommdity(BehindManageCommodityImpl.java:159)
at com.meeMei.BehindFrame.CommodityInputPanel$6.actionPerformed(CommodityInputPanel.java:374)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
at java.awt.Component.processMouseEvent(Component.java:6038)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3260)
at java.awt.Component.processEvent(Component.java:5803)
at java.awt.Container.processEvent(Container.java:2058)
at java.awt.Component.dispatchEventImpl(Component.java:4410)
at java.awt.Container.dispatchEventImpl(Container.java:2116)
at java.awt.Component.dispatchEvent(Component.java:4240)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4322)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3986)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3916)
at java.awt.Container.dispatchEventImpl(Container.java:2102)
at java.awt.Window.dispatchEventImpl(Window.java:2429)
at java.awt.Component.dispatchEvent(Component.java:4240)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:275)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:172)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)

由于主键是自增长的，在更新用户信息时只是对除了主键外的其他信息进行了显示，可以加上主键属性，然后进行update，主键不会受影响；