Hibernate：org.hibernate.LazyInitializationException：无法初始化代理 – 没有会话

对数据库有以下查询：

Session session = EmployeesDAO.getSessionFactory().getCurrentSession(); List employees = new ArrayList(); try { session.beginTransaction(); String hqlQuery = "from Employee emp " + "left join fetch emp.employeesOffices employeesOffice " + "left join fetch employeesOffice.office employeesOfficeOffice " + "left join fetch employeesOfficeOffice.company " + "left join fetch emp.address empAddress " + "left join fetch empAddress.city empAddressCity " + "left join fetch empAddressCity.country"; Query empQuery = session.createQuery(hqlQuery); empQuery.setMaxResults(maxResult); employees = (List) empQuery.list(); session.getTransaction().commit(); } catch (HibernateException e) { session.getTransaction().rollback(); e.printStackTrace(); } 

在获取employee.address.street，employee.address.houseNumber或employee.address.city时，它失败并出现exception：

 org.hibernate.LazyInitializationException: could not initialize proxy - no Session at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:164) at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:285) at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.invoke(JavassistLazyInitializer.java:185) at com.employees.model.Address_$$_javassist_6.getCity(Address_$$_javassist_6.java) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at javax.el.BeanELResolver.getValue(BeanELResolver.java:87) at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:67) at org.apache.el.parser.AstValue.getValue(AstValue.java:169) at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:189) at org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:985) at org.apache.jsp.WEB_002dINF.listEmployees_jsp._jspx_meth_c_005fout_005f3(listEmployees_jsp.java:306) at org.apache.jsp.WEB_002dINF.listEmployees_jsp._jspx_meth_c_005fforEach_005f1(listEmployees_jsp.java:248) at org.apache.jsp.WEB_002dINF.listEmployees_jsp._jspx_meth_c_005fforEach_005f0(listEmployees_jsp.java:155) at org.apache.jsp.WEB_002dINF.listEmployees_jsp._jspService(listEmployees_jsp.java:89) at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432) at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390) at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334) at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:690) at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:477) at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:402) at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:329) at com.employees.controller.EmployeeController.processRequest(EmployeeController.java:69) at com.employees.controller.EmployeeController.doGet(EmployeeController.java:30) at javax.servlet.http.HttpServlet.service(HttpServlet.java:621) at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98) at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1001) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:585) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source) 

员工映射：

       EMP_SEQ            

地址映射：

       ADDRESS_SEQ        

其他课程（办公室，公司等）绝对正常。 如果注释在jsp应用程序中加载地址字段的行没有任何例外。 怎么了？ 顺便说一句，它显示了有关jsp的所有信息，尽管有例外。

Answer 1

employee内部的对象是lazy初始化的。 这意味着，他们只是根据非封闭会话的需求进行初始化。 所以你必须在从DB获取之后在循环内手动初始化它们：

 Query empQuery = session.createQuery(hqlQuery); empQuery.setMaxResults(maxResult); employees = (List) empQuery.list(); for (Employee emp : employees) { Hibernate.initialize(emp.address); } 

Answer 2

Sinche Hibernate 4.2你可以使用

 .setProperty("hibernate.enable_lazy_load_no_trans", "true"); 

这个选项解决了可怕的问题

 org.hibernate.LazyInitializationException: could not initialize proxy - no Session 

这花了很多时间让程序员离开。

Answer 3

与映射无关。 当你在一个对象上提供延迟加载时，你接受一个让ORM世界迷惑了十年的责任：你加载对象的会话将与发出延迟请求时出现的会话相同 。

在您的情况下，看起来会话已完全消失。

您必须有一些方法来维护会话（这通常会导致需要会话范围，这意味着Seam或CDI（在EE 6中））或者您必须使用您拥有的新会话重新同步对象（通常再看一遍）。

Answer 4

将laze=false添加到或者当您从db获取对象时，可以在Hibernate.init（Object）中初始化对象