我试图坚持上课时遇到问题......
Hibernate抛出此异常：
Root cause:
java.lang.NullPointerException: null entities are not supported by org.hibernate.event.def.EventCache
at org.hibernate.event.def.EventCache.containsKey(EventCache.java:80)
at org.hibernate.event.def.DefaultMergeEventListener.mergeTransientEntity(DefaultMergeEventListener.java:361)
at org.hibernate.event.def.DefaultMergeEventListener.entityIsTransient(DefaultMergeEventListener.java:303)
at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:258)
at org.hibernate.event.def.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:84)
at org.hibernate.impl.SessionImpl.fireMerge(SessionImpl.java:867)
at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:851)
at org.hibernate.impl.SessionImpl.merge(SessionImpl.java:855)
at com.mycompany.myapp.service.data.DataServiceBean.merge(DataServiceBean.java:1337)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:309)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
at $Proxy64.merge(Unknown Source)
at com.mycompany.myapp.web.base.BaseForm.store(BaseForm.java:991)
at com.mycompany.myapp.web.base.BaseForm.store(BaseForm.java:942)
at com.mycompany.myapp.web.forms.therapie.TherapieForm.onSaveFormData(TherapieForm.java:591)
at com.mycompany.myapp.web.base.BaseForm.doSave(BaseForm.java:370)
at com.mycompany.myapp.web.base.BaseForm.saveAndTrigger(BaseForm.java:1137)
at com.mycompany.myapp.web.forms.reason.GrundEingabeForm$5.onSubmit(GrundEingabeForm.java:302)
at com.mycompany.myapp.web.comp.MyAppAjaxButton$1.onSubmit(MyAppAjaxButton.java:65)
at com.mycompany.myapp.web.comp.MyAppAjaxFormSubmitBehavior.onEvent(MyAppAjaxFormSubmitBehavior.java:151)
at org.apache.wicket.ajax.AjaxEventBehavior.respond(AjaxEventBehavior.java:177)
at org.apache.wicket.ajax.AbstractDefaultAjaxBehavior.onRequest(AbstractDefaultAjaxBehavior.java:286)
at org.apache.wicket.request.target.component.listener.BehaviorRequestTarget.processEvents(BehaviorRequestTarget.java:119)
at org.apache.wicket.request.AbstractRequestCycleProcessor.processEvents(AbstractRequestCycleProcessor.java:92)
at org.apache.wicket.RequestCycle.processEventsAndRespond(RequestCycle.java:1250)
at org.apache.wicket.RequestCycle.step(RequestCycle.java:1329)
at org.apache.wicket.RequestCycle.steps(RequestCycle.java:1428)
at org.apache.wicket.RequestCycle.request(RequestCycle.java:545)
at org.apache.wicket.protocol.http.WicketFilter.doGet(WicketFilter.java:479)
at org.apache.wicket.protocol.http.WicketFilter.doFilter(WicketFilter.java:312)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1139)
at org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter.doFilterInternal(OpenEntityManagerInViewFilter.java:113)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1139)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:378)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:417)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:324)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:535)
at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:880)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:747)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:218)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at org.mortbay.jetty.bio.SocketConnector$Connection.run(SocketConnector.java:228)
at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:520)
起初，Therapie类有一个在数据库中不能为null的属性，我认为抛出此异常是因为该属性为null ...但我摆脱了对数据库的约束（现在该属性可以为空的）当属性在被保存时没有值时，异常会被抛出。
如果该属性不为null（它具有值集），则不抛出异常，但如果它没有值（为null）则抛出异常......
发生了什么事？
答案 0 :(得分：1)
好吧，这个类正在扩展另一个有一个标记为不可选的getWeight（）方法......所以我只是愚蠢....