org.hibernate.AssertionFailure: null id in cn.allo

[framework] 2008-08-02 13:34:53,046 - org.apache.struts.action.RequestProcessor -10674171 [TP-Processor6] WARN  org.apache.struts.action.RequestProcessor  - Unhandled Exception thrown: class org.hibernate.AssertionFailure
[framework] 2008-08-02 13:35:02,937 - org.hibernate.AssertionFailure -10684062 [TP-Processor6] ERROR org.hibernate.AssertionFailure  - an assertion failure occured (this may indicate a bug in Hibernate, but is more likely due to unsafe use of the session)
org.hibernate.AssertionFailure: null id in cn.allobject.db.AReview entry (don't flush the Session after an exception occurs)
at org.hibernate.event.def.DefaultFlushEntityEventListener.checkId(DefaultFlushEntityEventListener.java:48)
at org.hibernate.event.def.DefaultFlushEntityEventListener.getValues(DefaultFlushEntityEventListener.java:150)
at org.hibernate.event.def.DefaultFlushEntityEventListener.onFlushEntity(DefaultFlushEntityEventListener.java:106)
at org.hibernate.event.def.AbstractFlushingEventListener.flushEntities(AbstractFlushingEventListener.java:195)
at org.hibernate.event.def.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:76)
at org.hibernate.event.def.DefaultAutoFlushEventListener.onAutoFlush(DefaultAutoFlushEventListener.java:35)
at org.hibernate.impl.SessionImpl.autoFlushIfRequired(SessionImpl.java:954)
at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1526)
at org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:283)
at cn.allobject.daoimp.OperateColumnDaoImp.showColumn(OperateColumnDaoImp.java:78)
at cn.allobject.struts.action.ShowArticleAction.execute(ShowArticleAction.java:59)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:419)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:224)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1194)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite(RuleChain.java:164)
at org.tuckey.web.filters.urlrewrite.RuleChain.doRules(RuleChain.java:141)
at org.tuckey.web.filters.urlrewrite.UrlRewriter.processRequest(UrlRewriter.java:90)
at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:417)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at cn.java1995.filter.GZipFilter.doFilter(GZipFilter.java:38)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at cn.allobject.servlet.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:34)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:263)
at org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:190)
at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:283)
at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:767)
at org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:697)
at org.apache.jk.common.ChannelSocket$SocketConnection.runIt(ChannelSocket.java:889)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:690)
at java.lang.Thread.run(Unknown Source)

很是奇怪的问题..
这个报AReview类的错误.
有人说这是因为保存对象的时候,数据库默认为空的字段,在hibernate的配置文件中设置了not-null="true"

但我的没有这个问题