我正在尝试将实体类持久化在数据库中，为此，我尝试了几种针对我的类的实现，但仍然面临错误（但存在不同的错误）。我的实体类现在像这样：
@Entity @Table(name="pagina") public class Pagina extends Entidade { @Id @Column(name = "id") @GeneratedValue(strategy=GenerationType.IDENTITY) private Integer Id; @Column(name = "nome", unique=true) private String nome; @Column(name = "titulo") private String titulo; @Column(name = "descricao") private String descricao; @OneToOne( cascade = {CascadeType.ALL}, fetch = FetchType.EAGER ) @JoinColumn(name="parent_page") @Cascade(org.hibernate.annotations.CascadeType.ALL) private Pagina pagina; @OneToOne( cascade = {CascadeType.ALL}, fetch = FetchType.EAGER ) @JoinColumn(name="parent_product") @Cascade(org.hibernate.annotations.CascadeType.ALL) private Produto produto; }
在我的Dao类中，我为我的方法尝试了这两种实现persist(...)：
persist(...)
@Transactional public boolean persist(E transientInstance) { try { sessionFactory.getCurrentSession().persist(transientInstance); return true; } catch (RuntimeException e) { e.printStackTrace(); return false; } }
和
@Transactional public boolean persist(E transientInstance) { try { sessionFactory.getCurrentSession().save(transientInstance); return true; } catch (RuntimeException e) { e.printStackTrace(); return false; } }
使用这两个选项时，如果我尝试保存没有属性Pagina或Produto的实体，则该实体将毫无问题地存储在数据库中。但是，如果我尝试使用此属性提交数据，则会遇到问题。
在第一个选项中，将org.hibernate.PersistentObjectException: detached entity passed to persist触发异常，在第二个选项中，数据将存储在数据库中，但是会出错，因为数据库中存储了没有值的额外行，并且插入了带有数据的行到那条线。
org.hibernate.PersistentObjectException: detached entity passed to persist
有人知道这里发生了什么吗？因为我不知道。
PS：
我有此视图在该表中插入数据：
<html lang="en"> <head> <title>Pagina</title> </head> <body> <h1>Cadastro de Pagina</h1> <form id="command" role="form" class="form" action="Pagina/cadastra" method="post"> <div class="panel panel-default"> <div class="panel-heading"> </div> <div class="panel-body"> <p> <label for="nome" class="form-control">nome</label> <input id="nome" name="nome" class="form-control" type="text" value=""/> </p> <p> <label for="titulo" class="form-control">titulo</label> <input id="titulo" name="titulo" class="form-control" type="text" value=""/> </p> <p> <label for="descricao" class="form-control">descricao</label> <textarea id="descricao" name="descricao" class="form-control"></textarea> </p> </div> </div> <div class="panel panel-default"> <div class="panel-heading"> Pagina </div> <div class="panel-body"> <input type="checkbox" name="Pagina.id" value="2">two<br> <input type="checkbox" name="Pagina.id" value="1">one<br> </div> </div> <div class="panel panel-default"> <div class="panel-heading"> Produto </div> <div class="panel-body"> </div> </div> <p> <button type="submit" class="btn btn-lg btn-primary">Cadastrar</button> </p> </form> <div id="yes" class="alert alert-success" style="display: none;"> <strong>Pronto!</strong> Solicitação efetuada com sucesso. </div> <div id="not" class="alert alert-danger" style="display: none;"> <strong>Erro!</strong> Não foi possivel efetivar a sua solicitação. </div> </body> </html>
通过以下方法处理：
在控制器类中
@RequestMapping(value="cadastra", method=RequestMethod.POST) @ResponseBody public String cadastra(@ModelAttribute("object") E object, BindingResult result) { if(serv.cadastra(object)) return "yes"; else return "not"; }
在服务等级
@PreAuthorize("hasPermission(#user, 'cadastra_'+#this.this.name)") @Transactional public boolean cadastra(E e) { return dao.persist(e); }
更新
当我尝试插入实体时发生的错误的stacktrace：
org.hibernate.PersistentObjectException: detached entity passed to persist: com.spring.loja.model.pagina.persistence.model.Pagina at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:139) at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:801) at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:794) at org.hibernate.engine.spi.CascadingActions$7.cascade(CascadingActions.java:314) at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:350) at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:293) at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:161) at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:118) at org.hibernate.event.internal.AbstractSaveEventListener.cascadeBeforeSave(AbstractSaveEventListener.java:432) at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:265) at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:194) at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:125) at org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:206) at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:149) at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:75) at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:811) at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:784) at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:789) at com.spring.loja.config.generic.persistence.Dao.persist(Dao.java:33) at com.spring.loja.config.generic.persistence.Dao$$FastClassBySpringCGLIB$$ddbbe880.invoke(<generated>) at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204) at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:711) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157) at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:136) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:98) at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:262) at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:95) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:644) at com.spring.loja.model.pagina.persistence.PaginaHome$$EnhancerBySpringCGLIB$$7cc5cae5.persist(<generated>) at com.spring.loja.config.generic.service.service.cadastra(service.java:28) at com.spring.loja.config.generic.service.service$$FastClassBySpringCGLIB$$c92a3159.invoke(<generated>) at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204) at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:711) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157) at org.springframework.security.access.intercept.aopalliance.MethodSecurityInterceptor.invoke(MethodSecurityInterceptor.java:64) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:98) at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:262) at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:95) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:644) at com.spring.loja.model.pagina.service.PaginaService$$EnhancerBySpringCGLIB$$71a378e.cadastra(<generated>) at com.spring.loja.config.generic.controller.controller.cadastra(controller.java:69) at com.spring.loja.config.generic.controller.controller$$FastClassBySpringCGLIB$$c8cc444b.invoke(<generated>) at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204) at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:640) at com.spring.loja.model.pagina.controller.PaginaController$$EnhancerBySpringCGLIB$$8679f278_2.cadastra(<generated>) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:606) at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:215) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:745) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:686) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:936) at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:838) at javax.servlet.http.HttpServlet.service(HttpServlet.java:647) at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812) at javax.servlet.http.HttpServlet.service(HttpServlet.java:728) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118) at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:154) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:199) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:110) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:57) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:50) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192) at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160) at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:343) at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:260) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1023) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at java.lang.Thread.run(Thread.java:745) Jul 13, 2014 9:07:48 PM org.hibernate.AssertionFailure <init> ERROR: HHH000099: 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 com.spring.loja.model.pagina.persistence.model.Pagina entry (don't flush the Session after an exception occurs) Jul 13, 2014 9:07:48 PM org.apache.catalina.core.StandardWrapperValve invoke Grave: Servlet.service() for servlet [jsp_dispatcher] in context with path [/loja] threw exception [Request processing failed; nested exception is org.hibernate.AssertionFailure: null id in com.spring.loja.model.pagina.persistence.model.Pagina entry (don't flush the Session after an exception occurs)] with root cause org.hibernate.AssertionFailure: null id in com.spring.loja.model.pagina.persistence.model.Pagina entry (don't flush the Session after an exception occurs) at org.hibernate.event.internal.DefaultFlushEntityEventListener.checkId(DefaultFlushEntityEventListener.java:77) at org.hibernate.event.internal.DefaultFlushEntityEventListener.getValues(DefaultFlushEntityEventListener.java:192) at org.hibernate.event.internal.DefaultFlushEntityEventListener.onFlushEntity(DefaultFlushEntityEventListener.java:152) at org.hibernate.event.internal.AbstractFlushingEventListener.flushEntities(AbstractFlushingEventListener.java:231) at org.hibernate.event.internal.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:102) at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:55) at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1222) at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:425) at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.beforeTransactionCommit(JdbcTransaction.java:101) at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.commit(AbstractTransactionImpl.java:177) at org.springframework.orm.hibernate4.HibernateTransactionManager.doCommit(HibernateTransactionManager.java:555) at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:757) at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:726) at org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:478) at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:272) at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:95) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:644) at com.spring.loja.model.pagina.service.PaginaService$$EnhancerBySpringCGLIB$$71a378e.cadastra(<generated>) at com.spring.loja.config.generic.controller.controller.cadastra(controller.java:69) at com.spring.loja.config.generic.controller.controller$$FastClassBySpringCGLIB$$c8cc444b.invoke(<generated>) at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204) at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:640) at com.spring.loja.model.pagina.controller.PaginaController$$EnhancerBySpringCGLIB$$8679f278_2.cadastra(<generated>) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:606) at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:215) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:745) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:686) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:936) at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:838) at javax.servlet.http.HttpServlet.service(HttpServlet.java:647) at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812) at javax.servlet.http.HttpServlet.service(HttpServlet.java:728) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118) at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:154) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:199) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:110) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:57) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:50) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192) at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160) at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:343) at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:260) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1023) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at java.lang.Thread.run(Thread.java:745)
可以这样解释该错误（ouf，如何在不描述Hibernate / JPA的整个对象生命周期的情况下执行此操作？）：
使用JPA / Hibernate，您可以将类定义为Entity。这意味着该类的对象可以由Hibernate管理，并因此存储在数据库中。
Entity
@Entity public class Entity { /** ... */ }
当创建一个Entity（new Entity()）类的新对象时，Hibernate对此一无所知。它不存储在数据库中，也不以任何方式受到Hibernate的控制。如果我们希望这些事情发生，我们需要persist对象（em.persist(entity)）。当我们这样做时，对象状态存储在数据库中，而且对象本身也由Hibernate管理，这意味着Hibernate将跟踪对象的状态。另外，如果您已将Hibernate分配为生成ID，则将为该对象分配ID。
new Entity()
persist
em.persist(entity)
通过Hibernate从数据库加载对象时，该对象也将由Hibernate管理。一个新持久的对象或一个加载的对象都将具有一个ID，并且都将由Hibernate管理。但是，对象和Hibernate之间的连接可能会断开！发生这种情况时，对象变为detached。一个detached对象实际上只是一个entity具有其ID设置的类的对象，但是不受Hibernate管理。
detached
entity
当涉及到一个detached对象时，我们所拥有的选择不同于我们使用托管对象或新对象所具有的选择。与托管对象不同，detached不允许将对象传递给persist-method，因为它们已经具有ID，这意味着它们必须已经被持久保存了！当想要获取一个detached对象并对其进行管理时，merge-method是一种可以使用的方法。（http://docs.oracle.com/javaee/7/api/javax/persistence/EntityManager.html#merge(T）） 这会将合并的对象的状态与对应于对象ID的数据库状态合并。
merge
merge使用新对象（不带id）进行调用将为其分配一个ID并保存，但要注意，它将对象作为参数传递时它不会做任何事情，而是会返回托管对象。
public Entity saveDetached(final Entity entity) { return em.merge(entity); }
在您的情况下，解决方案将取决于一些因素，但是如果所引用的对象Pagina始终是数据库中已经存在的对象，那么我只需persist从中删除该操作的级联，并继续使用em.persist()（merge有其缺点。）可能是新的，有时您还需要添加一些逻辑来确定是否要持久化（持久化拥有的对象之前）。（我也觉得可能工作加载Pagina并Produto从数据库中，并将它们分配给新的Pagina面前persist。）
Pagina
em.persist()
Produto
TL; DR
将detached对象重新引入持久性上下文时，请使用merge-方法EntityManager，而不要使用persist-方法。
EntityManager
