hibernate - Spring + Hibernate 懒加载

Question

我有 org.hibernate.LazyInitializationException 问题:无法延迟初始化角色集合。

如何使用 gwt + spring + hibernate 实现延迟获取？

这是我的 appContext:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop" 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-3.0.xsd   http://www.springframework.org/schema/context   http://www.springframework.org/schema/context/spring-context-3.0.xsd   http://www.springframework.org/schema/tx   http://www.springframework.org/schema/tx/spring-tx-3.0.xsd   http://www.springframework.org/schema/aop    http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">
    <bean id="hibernateTemplate" class="org.springframework.orm.hibernate3.HibernateTemplate">
        <property name="sessionFactory">
            <ref local="sessionFactory"/>
        </property>
    </bean>
    <context:annotation-config/>
    <context:component-scan base-package="com.yeah.server.*"/>
    <aop:aspectj-autoproxy/>
    <!--Mysql database connection info-->
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://192.168.1.4:3306/YeaH"/>
        <property name="username" value="root"/>
        <property name="password" value=""/>
    </bean>
    <!-- Hibernate -->
    <bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <property name="mappingResources">
            <list>
                <value>com/yeah/shared/model/User.hbm.xml</value>
                <value>com/yeah/shared/model/Comment.hbm.xml</value>
                <value>com/yeah/shared/model/Album.hbm.xml</value>
                <value>com/yeah/shared/model/Picture.hbm.xml</value>
            </list>
        </property>
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
                <prop key="hibernate.show_sql">true</prop>
                <prop key="hibernate.hbm2ddl.auto">update</prop>
            </props>
        </property>
    </bean>
    <!--HIbernate session management
 <bean name="openSessionInViewInterceptor"
     class="org.springframework.orm.hibernate3.support.OpenSessionInViewInterceptor">
 <property name="sessionFactory" ref="sessionFactory"/>
 <property name="singleSession" value="false"/>
 </bean>
 -->
    <!-- a PlatformTransactionManager is still required -->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"/>
    </bean>
</beans>

Answer 1

发生异常是因为您在加载域对象的 hibernate session 关闭后尝试访问域对象上的延迟加载属性。

解决此问题的常用方法是使用 Spring OpenSessonInViewFilter。这实质上将您的 hibernate session 范围限定为您的 HTTP 请求。然后，在该 HTTP 请求/响应周期内发生的任何属性访问都将在该 session 的范围内。

您在 web.xml 中对其进行如下配置:

<filter>
    <filter-name>Spring OpenSessionInViewFilter</filter-name>
    <filter-class>
        org.springframework.orm.hibernate3.support.OpenSessionInViewFilter
    </filter-class>
</filter>

希望这可以帮助。