出现问题： 

SSH整合项目里，项目目录结构如下：

在EmployeeAction.java的list()方法里将employees的list放入到request的Map中。

EmployeeAction.java:

 package com.tt.ssh.actions;

 import java.util.Arrays;

 import java.util.Map;

 import org.apache.struts2.interceptor.RequestAware;

 import com.opensymphony.xwork2.ActionContext;

 import com.opensymphony.xwork2.ActionSupport;

 import com.opensymphony.xwork2.util.ValueStack;

 import com.tt.ssh.service.EmployeeService;

 public class EmployeeAction extends ActionSupport implements RequestAware{

     private static final long serialVersionUID = 1L;

     private EmployeeService employeeService;

     public void setEmployeeService(EmployeeService employeeService) {

         this.employeeService = employeeService;

     }

     Map<String, Object> request;

     public String list(){

         request.put("employees",employeeService.getAll());

         return "list";

     }

     @Override

     public void setRequest(Map<String, Object> arg0) {

         // TODO Auto-generated method stub

         this.request = arg0;

     }

 }

然后到emp-list.jsp页面上进行获取，发现始终都获取不到employees。

emp-list.jsp:

 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

 <title>Insert title here</title>

 </head>

 <body>

        <s:debug></s:debug>

        <center>

            <h4>list页面显示成功！</h4>

            <s:if test="#request.employees == null || #request.employees.size() == 0">

                  没有任何员工信息

            </s:if>

            <s:else>

                 <table border="1" cellpadding="10" cellspacing="0">

                     <s:iterator value="#request.employees" var="employee">

                         <tr>

                           <td>${employee.id }</td>

                           <td>${employee.lastName }</td>

                           <td>${employee.email }</td>

                           <td>${employee.birth }</td>

                           <td>${employee.createTime }</td>

                           <td>${employee.department.deptName }</td>

                         </tr>

                     </s:iterator>

                 </table>

            </s:else>

        </center>

 </body>

 </html>

排除jsp页面问题，于是进入怀疑在EmployeeAction里employees的list压根没放成功。

运行到第25行就报错，同时从ctx获取ContextMap进而获取request的Map时得到的为null,这说明employees的list确实没有放入到request的Map中。

报错如下：

Stacktraces

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

    org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:164)

    org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:285)

    org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.invoke(JavassistLazyInitializer.java:185)

    com.tt.ssh.entities.Department_$$_javassist_1.toString(Department_$$_javassist_1.java)

    java.lang.String.valueOf(String.java:2994)

    java.lang.StringBuilder.append(StringBuilder.java:131)

    com.tt.ssh.entities.Employee.toString(Unknown Source)

    java.lang.String.valueOf(String.java:2994)

    java.lang.StringBuilder.append(StringBuilder.java:131)

    java.util.AbstractCollection.toString(AbstractCollection.java:462)

    com.tt.ssh.actions.EmployeeAction.list(Unknown Source)

    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)

    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

    java.lang.reflect.Method.invoke(Method.java:498)

    ognl.OgnlRuntime.invokeMethod(OgnlRuntime.java:871)

    ognl.OgnlRuntime.callAppropriateMethod(OgnlRuntime.java:1294)

    ognl.ObjectMethodAccessor.callMethod(ObjectMethodAccessor.java:68)

    com.opensymphony.xwork2.ognl.accessor.XWorkMethodAccessor.callMethodWithDebugInfo(XWorkMethodAccessor.java:117)

    com.opensymphony.xwork2.ognl.accessor.XWorkMethodAccessor.callMethod(XWorkMethodAccessor.java:108)

    ognl.OgnlRuntime.callMethod(OgnlRuntime.java:1370)

    ognl.ASTMethod.getValueBody(ASTMethod.java:91)

    ognl.SimpleNode.evaluateGetValueBody(SimpleNode.java:212)

    ognl.SimpleNode.getValue(SimpleNode.java:258)

    ognl.Ognl.getValue(Ognl.java:467)

    ognl.Ognl.getValue(Ognl.java:431)

    com.opensymphony.xwork2.ognl.OgnlUtil$3.execute(OgnlUtil.java:352)

    com.opensymphony.xwork2.ognl.OgnlUtil.compileAndExecuteMethod(OgnlUtil.java:404)

    com.opensymphony.xwork2.ognl.OgnlUtil.callMethod(OgnlUtil.java:350)

    com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:430)

    com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:290)

    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:251)

    org.apache.struts2.interceptor.DeprecationInterceptor.intercept(DeprecationInterceptor.java:41)

    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)

    org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:256)

    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)

    com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:168)

    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)

    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)

    com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:265)

    org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:76)

    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)

    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)

    com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:138)

    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)

    com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:229)

    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)

    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)

    com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:229)

    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)

    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)

    com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:191)

    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)

    org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:73)

    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)

    org.apache.struts2.interceptor.DateTextFieldInterceptor.intercept(DateTextFieldInterceptor.java:125)

    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)

    org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:91)

    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)

    org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:253)

    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)

    com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100)

    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)

    com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141)

    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)

    com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145)

    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)

    com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:171)

    com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)

    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)

    com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:140)

    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)

    org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)

    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)

    com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:193)

    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)

    com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:189)

    com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)

    org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54)

    org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:575)

    org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:81)

    org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:99)

    org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)

    org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)

    org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)

    org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)

    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)

    org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)

    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)

    org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)

    org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)

    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:528)

    org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1100)

    org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:687)

    org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2508)

    org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2497)

    java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)

    java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)

    org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)

    java.lang.Thread.run(Thread.java:745)

 

 分析原因：

  EmployeeService.java:

 package com.tt.ssh.service;

 import java.util.List;

 import com.tt.ssh.dao.EmployeeDao;

 import com.tt.ssh.entities.Employee;

 public class EmployeeService {

     private EmployeeDao employeeDao;

     public void setEmployeeDao(EmployeeDao employeeDao) {

         this.employeeDao = employeeDao;

     }

     public List<Employee> getAll(){

         return employeeDao.getAll();

     }

 }

而EmployeeDao.java:

 package com.tt.ssh.dao;

 import java.util.List;

 import org.hibernate.Session;

 import org.hibernate.SessionFactory;

 import com.tt.ssh.entities.Employee;

 public class EmployeeDao {

     private SessionFactory sessionFactory;

     public void setSessionFactory(SessionFactory sessionFactory) {

         this.sessionFactory = sessionFactory;

     }

     public Session getSession(){

         return this.sessionFactory.getCurrentSession();

     }

     public List<Employee> getAll(){

         String hql = "FROM Employee";

         return getSession().createQuery(hql).list();

     }

 }

可以看到，employee的list是从Hibernate的session里获取的。

报错是一个懒加载异常，意识是在session（hibernate里的session）关闭后使用employee对象的未加载变量，也就是说session已经关闭，然而该实例变量却还没有被初始化，就使用了该实例变量，导致该异常。

applicationContext.xml配置如下：


由于employee是由hibernate进行加载的，可能hibernate本身是以load的方式将该实例变量得到。此时在employeeDao里session获取到的是的employee代理类对象，整个Session范围内，应用程序没有访问过employee对象，那么employee代理类的实例一直不会被初始话。事务是作用在EmployeeService上，导致
List<Employee> getAll( )方法调用之前获取Session、开启事务，这个方法结束之后提交事务、关闭session。session关闭后，在EmployeeAction获取employee时是未初始化的employee代理类对象，未被初始化的代理类对象只有OID其他属性全为null，那么放入request的Map里的是未被初始化的employee代理类对象。一旦在action或者jsp里要获取employee代理类对象，必然会发生懒加载异常。同理，在jsp里获取employee的department时同样存在懒加载的问题。
(关于hiberante的延迟加载，更详细的在我的另一篇博客里：http://www.cnblogs.com/TTTTT/p/6682304.html)

解决办法：

方法1.用openSessionInView 。
方法2.把这个类的延迟加载禁掉，lazy设为false。
方法3.迫切左外连接。

Hibernate和Spring整合出现懒加载异常：org.hibernate.LazyInitializationException: could not initialize proxy - no Session的更多相关文章

  1. SpringBoot JPA懒加载异常 - com.fasterxml.jackson.databind.JsonMappingException: could not initialize proxy

    问题与分析 某日忽然发现在用postman测试数据时报错如下: com.fasterxml.jackson.databind.JsonMappingException: could not initi ...

  2. dubbo序列化hibernate.LazyInitializationException could not initialize proxy - no Session懒加载异常的解决

    dubbo序列化,hibernate.LazyInitializationException could not initialize proxy - no Session懒加载异常的解决 转载声明: ...

  3. 总结懒加载的解决方法(全)org.hibernate.LazyInitializationException: could not initialize proxy - no Session

    如下错误:org.hibernate.LazyInitializationException: could not initialize proxy - no Session 原因是懒加载的问题,因为 ...

  4. Spring Boot JPA 懒加载

    最近在使用spring jpa 的过程中经常遇到懒加载的错误:"` org.hibernate.LazyInitializationException: could not initiali ...

  5. Hibernate第八篇【懒加载】

    前言 前面在使用Hibernate的时候就提及过了懒加载,但没有好好地说明具体的说明究竟是怎么回事-本博文主要讲解懒加载 什么是拦截器以及为什么要使用懒加载? 懒加载就是当使用数据的时候才去获取数据. ...

  6. 在web.xml中添加配置解决hibernate 懒加载异常

    在web.xml添加如下,注意:在配置在struts2的拦截器之前,只能解决请求时出现的懒加载异常:如果没有请求,还需要lazy属性的添加(比如过滤器) <!-- 配置Spring的用于解决懒加 ...

  7. 【转】hibernate懒加载的问题，failed to lazily initialize a collection of role

    hibernate懒加载的问题,failed to lazily initialize a collection of role hibernate懒加载的问题,failed to lazily in ...

  8. jpa懒加载异常

    1.项目背景概述 事情是这样子的,使用了spring data jpa的项目jeesite jeesite的实体中使用了懒加载模式. 并且一个实体类中还不止一个属性设置了懒加载模式. 项目本身已经存在 ...

  9. 关于Web项目出现懒加载异常的解决方案

    manytomany关系中,使用 fetch = FetchType.LAZY 来做懒加载,加快些性能.但是却一直出错,原因是session被关闭,要保持session,需要事务. Hibernate ...

随机推荐

  1. 【TCP/IP详解 卷一：协议】TCP定时器 小结

    前言 在有关TCP的章节中,介绍了四种定时器,它们体现了TCP的可靠性,其中最重要的 就是重传定时器了,剩下的定时器都是为了解决TCP的理解上的一些问题而设置的. 四种定时器: 2MSL定时器,出现在 ...

  2. MVC 枚举绑定 DropDownList

    /// <summary> /// 枚举转化下拉列表数据集 /// </summary> /// <param name="type">类型&l ...

  3. [ios]iOS8 定位

    参考:http://www.2cto.com/kf/201410/342392.html http://blog.csdn.net/yongyinmg/article/details/39521523 ...

  4. 技术分享：SSH实战项目

    1.需求分析 系统概述: 企业人事管理系统. 要求对员工信息进行维护. 后台系统先登录,才能操作员工;添加.修改.删除. 没有登录,只能查看列表,不能操作. 功能分类: 1)[管理员模块] 注册/登录 ...

  5. Unity生成屏幕快照

    public static Texture2D CaptureCamera(Camera camera, Rect rect) { RenderTexture rt = ); RenderTextur ...

  6. Python 爬虫-正则表达式（补）

    2017-08-08 18:37:29 一.Python中正则表达式使用原生字符串的几点说明 原生字符串和普通字符串的不同 相较于普通字符串,原生字符串中的\就是反斜杠,并不表达转义.不过,字符串转成 ...

  7. ubuntu , 笔记本合上盖子时不关机的方法。

    实测ubuntu 14.04 好使 1) 编辑 /etc/systemd/logind.conf 2) 找到 HandleLidSwitch 设置,去掉行头注释#,然后改成下面这样 HandleLid ...

  8. 『TensorFlow』通过代码理解gan网络_中

    『cs231n』通过代码理解gan网络&tensorflow共享变量机制_上 上篇是一个尝试生成minist手写体数据的简单GAN网络,之前有介绍过,图片维度是28*28*1,生成器的上采样使 ...

  9. EBS OAF开发中的错误/异常处理(ErrorHandling) (转)

    原文地址 EBS OAF开发中的错误/异常处理(ErrorHandling) EBS OAF开发中的错误/异常处理(ErrorHandling) (版权声明,本人原创或者翻译的文章如需转载,如转载用于 ...

  10. java keytool详解

    Keytool 是一个Java 数据证书的管理工具 ,Keytool 将密钥(key)和证书(certificates)存在一个称为keystore的文件中. 在keystore里,包含两种数据:(1 ...