org.hibernate.AssertionFailure：[域对象]条目中的空 id

Question

我有一个使用 Tomcat、MySQL 和 Hibernate 的 Java EE Web 应用程序。 在我的本地安装（Windows）中，一切都很完美。将导出的 war 文件放到服务器 (Linux Fedora) 上，运行应用程序时出现错误。

运行应用程序，我将尝试获取项目列表。在我的 Dao 实现中，我这样做：

public Set<Project> getAllProjects() {
    SessionFactory sessionFactory = HibernateUtil.getSessionFactory();
    Session sess = sessionFactory.getCurrentSession();
    Transaction tx = sess.beginTransaction();
    @SuppressWarnings("unchecked")
    List<Project> list = sess.createQuery("from Project").list();
    Set<Project> projects = new HashSet<Project>(list);
    tx.commit();
    return projects;
}

但我收到此错误，请参见下文。

此错误行（我看到的最后一行是我自己编写的文件）：

at com.myDomain.myProject.dao.impl.ProjectDaoImplHibernate.getAllProjects(ProjectDaoImplHibernate.java:75)

是这行代码吗：

List<Project> list = sess.createQuery("from Project").list();

那么，这里有什么问题？

非常感谢您的帮助，最好的问候。

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 com.myDomain.myProject.domain.Project entry (don't flush the Session after an exception occurs)
at org.hibernate.event.def.DefaultFlushEntityEventListener.checkId(DefaultFlushEntityEventListener.java:82)
at org.hibernate.event.def.DefaultFlushEntityEventListener.getValues(DefaultFlushEntityEventListener.java:190)
    at org.hibernate.event.def.DefaultFlushEntityEventListener.onFlushEntity(DefaultFlushEntityEventListener.java:147)
    at org.hibernate.event.def.AbstractFlushingEventListener.flushEntities(AbstractFlushingEventListener.java:219)
    at org.hibernate.event.def.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:99)
    at org.hibernate.event.def.DefaultAutoFlushEventListener.onAutoFlush(DefaultAutoFlushEventListener.java:58)
    at org.hibernate.impl.SessionImpl.autoFlushIfRequired(SessionImpl.java:1185)
    at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1261)
    at org.hibernate.impl.QueryImpl.list(QueryImpl.java:102)
    at com.myDomain.myProject.dao.impl.ProjectDaoImplHibernate.getAllProjects(ProjectDaoImplHibernate.java:75)
    at com.myDomain.myProject.service.impl.ProjectServiceImpl.getAllProjects(ProjectServiceImpl.java:47)
    at com.myDomain.myProject.controller.ProjectPersonController.getAllProjects(ProjectPersonController.java:60)
    at sun.reflect.GeneratedMethodAccessor47.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:616)
    at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:176)
    at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:426)
    at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:414)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:790)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:549)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:646)
    at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:436)
    at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:374)
    at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:302)
    at org.tuckey.web.filters.urlrewrite.NormalRewrittenUrl.doRewrite(NormalRewrittenUrl.java:195)
    at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite(RuleChain.java:159)
    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 org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
    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:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    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:298)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    at java.lang.Thread.run(Thread.java:636)

Answer 1

重新启动Tomcat两次，没有出现错误。每次我将新的 .war 文件放入其中时，我都必须这样做。