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更新struts版本导致的org.hibernate.LazyInitializationException（懒加载异常）原因

程序员文章站 2022-03-02 14:32:31
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报错内容

报错信息如下所示：

org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.xmgrid.bizDo.cd.po.User.role, no session or session was closed
	at org.hibernate.collection.internal.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:393)
	at org.hibernate.collection.internal.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:385)
	at org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:378)
	at org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:112)
	at org.hibernate.collection.internal.PersistentBag.iterator(PersistentBag.java:266)
	at com.xmgrid.view.cd.action.LoginAction.index(LoginAction.java:264)
	at com.xmgrid.view.cd.action.LoginAction.login(LoginAction.java:248)
	at com.xmgrid.view.cd.action.LoginAction.execute(LoginAction.java:57)
	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 ognl.OgnlRuntime.invokeMethod(OgnlRuntime.java:892)
	at ognl.OgnlRuntime.callAppropriateMethod(OgnlRuntime.java:1294)
	at ognl.ObjectMethodAccessor.callMethod(ObjectMethodAccessor.java:68)
	at com.opensymphony.xwork2.ognl.accessor.XWorkMethodAccessor.callMethodWithDebugInfo(XWorkMethodAccessor.java:117)
	at com.opensymphony.xwork2.ognl.accessor.XWorkMethodAccessor.callMethod(XWorkMethodAccessor.java:108)
	at ognl.OgnlRuntime.callMethod(OgnlRuntime.java:1370)
	at ognl.ASTMethod.getValueBody(ASTMethod.java:91)
	at ognl.SimpleNode.evaluateGetValueBody(SimpleNode.java:212)
	at ognl.SimpleNode.getValue(SimpleNode.java:258)
	at ognl.Ognl.getValue(Ognl.java:467)
	at ognl.Ognl.getValue(Ognl.java:431)
	at com.opensymphony.xwork2.ognl.OgnlUtil$3.execute(OgnlUtil.java:352)
	at com.opensymphony.xwork2.ognl.OgnlUtil.compileAndExecuteMethod(OgnlUtil.java:404)
	at com.opensymphony.xwork2.ognl.OgnlUtil.callMethod(OgnlUtil.java:350)
	at com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:430)
	at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:290)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:251)
	at com.xmgrid.view.common.XssIntecepter.intercept(XssIntecepter.java:127)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at com.xmgrid.view.common.LoginIntecepter.intercept(LoginIntecepter.java:29)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at org.apache.struts2.interceptor.DeprecationInterceptor.intercept(DeprecationInterceptor.java:41)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:256)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:168)
	at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:265)
	at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:76)
	at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:138)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:229)
	at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:229)
	at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:191)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:73)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at org.apache.struts2.interceptor.DateTextFieldInterceptor.intercept(DateTextFieldInterceptor.java:125)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:91)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:253)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:171)
	at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:140)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:193)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:189)
	at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:245)
	at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54)
	at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:575)
	at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:81)
	at org.apache.struts2.dispatcher.ng.filter.StrutsExecuteFilter.doFilter(StrutsExecuteFilter.java:93)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
	at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareFilter.doFilter(StrutsPrepareFilter.java:91)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
	at com.xmgrid.view.filter.HttpHostFilter.doFilter(HttpHostFilter.java:29)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
	at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:956)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423)
	at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:625)
	at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:318)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:745)

使用懒加载的好处

当我们要访问的数据量过大时，明显用缓存不太合适，
因为内存容量有限 ，为了减少并发量，减少系统资源的消耗，
我们让数据在需要的时候才进行加载，这时我们就用到了懒加载

解决方法：

亲自尝试过的方法有两种（比较推荐的是第二种）：

1. 去除hibernate懒加载的注解：

（1）注解配置形式

	@ManyToMany(cascade={CascadeType.MERGE,CascadeType.REFRESH},fetch=FetchType.LAZY)
	@JoinTable(name="user_role",inverseJoinColumns={@JoinColumn(name="roleId")},joinColumns={@JoinColumn(name="userId")})
	private List<Role> role = new ArrayList<Role>();//角色

懒加载的两种配置：

FetchType.LAZY：懒加载，加载一个实体时，定义懒加载的属性不会马上从数据库中加载

FetchType.EAGER：急加载，加载一个实体时，定义急加载的属性会立即从数据库中加载

（2）xml配置形式

<hibernate-mapping>
　<class name=”com.neusoft.entity.User” table=”user” lazy=”true”>
   　……
　</class>
</hibernate-mapping>

解决方法：

因此解决这个报错，如果是注解形式的配置我们****可以将项目中的懒加载改为FetchType.EAGER就不会报org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.xmgrid.bizDo.cd.po.User.role, no session or session was closed这个错误。如果是配置的形式，则可以将lazy的值设置为false。因为使用懒加载有提高系统效率的好处，而且在项目中用到懒加载的实体类还是比较多的，所以用这个方法去解决报错有点治标不治本。

2.在过滤器中使用OpenSessionInViewFilter

配置如下所示：

  <filter>
    <filter-name>openSessionInViewFilter</filter-name>
    <filter-class>org.springframework.orm.hibernate4.support.OpenSessionInViewFilter</filter-class>
    <init-param>
      <param-name>sessionFactoryBeanName</param-name>
      <param-value>sessionFactory</param-value>
    </init-param>
  </filter>
  <filter-mapping>
    <filter-name>openSessionInViewFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>

注意事项：
用这个方法特别要注意的是openSessionInViewFilter的配置代码要写在struts配置的前面，否则也会报org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.xmgrid.bizDo.cd.po.User.role, no session or session was closed的错误。

知识扩展：

报错原因：

Hibernate允许对关联的对象，属性进行延迟加载，但是这个前提是必须保证延迟加载在同一个Hibernate Session范围之内进行。在实际开发中，都是采用分层的模式进行开发的，如果要在action层中使用一个由Service层返回的业务对象，延迟加载关联对象事，因加载领域对象的 Hibernate Session 已经关闭，这些导致延迟加载数据的访问异常。

openSessionInViewFilter作用：

OpenSessionInViewFilter的主要功能是用来把一个Hibernate Session和一次完整的请求过程对应的线程相绑定。目的是为了实现"Open Session in View"的模式。例如： 它允许在事务提交之后延迟加载显示所需要的对象。
OpenSessionInViewFilter 过滤器将 Hibernate Session 绑定到请求线程中，它将自动被 Spring 的事务管理器探测到。所以 OpenSessionInViewFilter 适用于 Service 层使用HibernateTransactionManager 或 JtaTransactionManager 进行事务管理的环境，也可以用于非事务只读的数据操作中。

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