Question

我正在尝试使用OpenEntityManageInViewFilter，但我一直在使用LazyInitializationException。将EntityManager初始化两次时，人们遇到了类似的问题 - 但这似乎不是我的情况。在异常日志中我可以看到，过滤器正在正常触发。

的web.xml：

<web-app version="2.4"
    xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="
        http://java.sun.com/xml/ns/j2ee
        http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

    <servlet>
        <servlet-name>web-application</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>web-application</servlet-name>
        <url-pattern>/*</url-pattern>
    </servlet-mapping>

    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>WEB-INF/web-application-servlet.xml</param-value>
    </context-param>

    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

    <filter>
        <filter-name>openEntityManageInViewFilter</filter-name>
        <filter-class>org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter</filter-class>
    </filter>

    <filter-mapping>
        <filter-name>openEntityManageInViewFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

</web-app>

web的应用程序-servlet.xml中

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
            http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
            http://www.springframework.org/schema/context
            http://www.springframework.org/schema/context/spring-context-3.1.xsd
            http://www.springframework.org/schema/tx
            http://www.springframework.org/schema/tx/spring-tx-3.1.xsd">

    <import resource="classpath:applicationContext.xml"/>
    <context:property-placeholder location="classpath:application.properties"/>

    <bean id="viewResolver" class="org.springframework.web.servlet.view.freemarker.FreeMarkerViewResolver">
        <property name="viewNames" value="*" />
        <property name="cache" value="false"/>
        <property name="prefix" value=""/>
        <property name="suffix" value=".ftl"/>
        <property name="exposeSpringMacroHelpers" value="false"/>
    </bean>

    <bean id="handlerAdapter" autowire="byType" class="org.maite.controller.router.HandlerAdapter" />
    <bean id="handlerMapping" autowire="byType" class="org.maite.controller.router.HandlerMapping" />
</beans>

的applicationContext.xml

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
            http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
            http://www.springframework.org/schema/context
            http://www.springframework.org/schema/context/spring-context-3.1.xsd
            http://www.springframework.org/schema/tx
            http://www.springframework.org/schema/tx/spring-tx-3.1.xsd">


    <tx:annotation-driven />
    <context:annotation-config/>
    <context:spring-configured/>

    <bean id="entityManagerFactory"
          class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="persistenceUnitName" value="persistenceUnit"/>
    </bean>

    <bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" />
</beans>

异常（你可以看到OpenEntityManagerInView占用了堆栈跟踪的一部分）：

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: org.goout.model.Event.schedule, no session or session was closed
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:894)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
    org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter.doFilterInternal(OpenEntityManagerInViewFilter.java:147)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
root cause

org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: org.goout.model.Event.schedule, no session or session was closed
    org.hibernate.collection.internal.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:393)
    org.hibernate.collection.internal.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:385)
    org.hibernate.collection.internal.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:378)
    org.hibernate.collection.internal.AbstractPersistentCollection.read(AbstractPersistentCollection.java:112)
    org.hibernate.collection.internal.PersistentSet.toArray(PersistentSet.java:188)
    java.util.ArrayList.<init>(ArrayList.java:151)
    freemarker.template.SimpleSequence.<init>(SimpleSequence.java:162)
    freemarker.template.DefaultObjectWrapper.wrap(DefaultObjectWrapper.java:117)
    freemarker.template.WrappingTemplateModel.wrap(WrappingTemplateModel.java:134)
    freemarker.template.SimpleHash.get(SimpleHash.java:224)
    freemarker.core.Dot._getAsTemplateModel(Dot.java:76)
    freemarker.core.Expression.getAsTemplateModel(Expression.java:89)
    freemarker.core.IteratorBlock.accept(IteratorBlock.java:94)
    freemarker.core.Environment.visit(Environment.java:221)
    freemarker.core.MixedContent.accept(MixedContent.java:92)
    freemarker.core.Environment.visit(Environment.java:221)
    freemarker.core.Environment.visit(Environment.java:310)
    freemarker.core.BlockAssignment.accept(BlockAssignment.java:83)
    freemarker.core.Environment.visit(Environment.java:221)
    freemarker.core.MixedContent.accept(MixedContent.java:92)
    freemarker.core.Environment.visit(Environment.java:221)
    freemarker.core.Environment.process(Environment.java:199)
    freemarker.template.Template.process(Template.java:237)
    org.springframework.web.servlet.view.freemarker.FreeMarkerView.processTemplate(FreeMarkerView.java:366)
    org.springframework.web.servlet.view.freemarker.FreeMarkerView.doRender(FreeMarkerView.java:283)
    org.springframework.web.servlet.view.freemarker.FreeMarkerView.renderMergedTemplateModel(FreeMarkerView.java:233)
    org.springframework.web.servlet.view.AbstractTemplateView.renderMergedOutputModel(AbstractTemplateView.java:167)
    org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:262)
    org.maite.DispatcherServlet.doService(DispatcherServlet.java:38)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
    org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter.doFilterInternal(OpenEntityManagerInViewFilter.java:147)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)

Answer 1

您遇到与this question中描述的问题相同的问题，这意味着您有2个EntityManager bean - 这会引起混淆。

基本上你需要删除

<import resource="classpath:applicationContext.xml"/>

来自web-application-context.ml，对您的bean进行分区，使得Web层和应用程序bean位于单独的上下文文件中，并确保每个组件中的组件扫描都会获取正确的bean。这可能需要将类移到不同的包中，如果没有关于项目结构的更多信息，很难提供建议。

最后从web.xml

引用两个上下文

Answer 2

请您提供无法初始化另一个DAO类集合的DAO类？

尝试将这些参数放在过滤器中的web.xml中。

<init-param>
        <param-name>entityManagerFactoryBeanName</param-name>
        <param-value>entityManagerFactory</param-value>
</init-param>

即使使用OpenEntityManagerInViewFilter也会出现LazyInitializationException

2 个答案: