Hibernate和Spring整合出现懒加载异常：org.hibernate.LazyInitializationException: could not initialize proxy - no Session
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
- 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 ...
- 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: ...
- 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 ...
- 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 ...
- 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. ...
- 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 ...
- 【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 ...
- 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 ...
- 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
- WPF基础学习笔记整理 （九） 资源
基础知识: WPF的资源是一种保管一系列有用对象的简单方法,方便于重用. WPF UI元素的Resources属性,都是继承自FrameworkElement列,且其类型为ResourceDictio ...
- Python day8常用格式化format类2
format常用格式化 tp1="i am {},age {},{}".format('LittlePage',18,'boy') tp2="i am {},age {} ...
- MongoDB（课时27 消除重复数据）
3.7.2 消除重复数据 在SQL中对于重复的数据可以使用"DISTINCT"消除,在MongoDB中依然支持.(distinct不同的) 范例:查询所有name的信息 本次的操作 ...
- django多对多中间表详解
我们都知道对于ManyToMany字段,Django采用的是第三张中间表的方式.通过这第三张表,来关联ManyToMany的双方.下面我们根据一个具体的例子,详细解说中间表的使用. 一.默认中间表 首 ...
- VC动态调用DLL
1. //函数指针声明 typedef int (_stdcall MYDLLFUN)(char* _pcOut, /*INOUT*/int *_piOutBufLen, char* _pcIn, i ...
- 《剑指offer》第十七题（打印1到最大的n位数）
// 面试题17:打印1到最大的n位数 // 题目:输入数字n,按顺序打印出从1最大的n位十进制数.比如输入3,则 // 打印出1.2.3一直到最大的3位数即999. #include <ios ...
- react notes
jsx 在JSX中嵌入用户输入是安全的,默认情况下, 在渲染之前, React DOM 会格式化(escapes) JSX中的所有值. 从而保证用户无法注入任何应用之外的代码. 在被渲染之前,所有的数 ...
- crond 的注意点
本来在控制台调试的好好的程序,一通过crond运行, 就执行不了. 一般需要注意: 1) 环境变量 当前目录 会变成用户的Home 2) /var/log/messages 可以看出 crond 调 ...
- C# WPF 利用NPOI读写Excel文件
https://blog.csdn.net/a312024054/article/details/70139172 [各种样式] https://www.cnblogs.com/xwgli/archi ...
- JavaScript 和 React，React用了大量语法糖，让JS编写更方便。
https://reactjs.org/docs/higher-order-components.htmlhttps://codepen.io/gaearon/pen/WooRWa?editors=0 ...