使用 OpenEntityManagerInViewFilter 进行延迟初始化？

Question

我有一个已经在工作的 JBoss webapp，还有一个延迟初始化问题。 因此建议我在 Spring 进行调查并使用OpenEntityManagerInViewFilter。

但是我仍然收到错误，希望您能帮助我吗？ 为了使用 Spring OEM 过滤器，我还需要在我的应用中进行哪些更改？

我的设置是这样的：

@Entity
class Customer;

@Stateless
@TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)
class DaoService {
  @PersistenceContext
  EntityManager em;
}

@Named
@RequestScoped
class CustomerFacade;

+jsf 的东西。

[javax.enterprise.resource.webcontainer.jsf.context] (http--127.0.0.1-8080-1) org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: domain.Customer.customerList, no session or session was closed

我是这样设置的： web.xml

<filter>
    <filter-name>
        OpenEntityManagerInViewFilter
    </filter-name>
    <filter-class>
        org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter
    </filter-class>
    <init-param>
        <param-name>singleSession</param-name>
        <param-value>true</param-value>
    </init-param>
    <init-param>
        <param-name>flushMode</param-name>
        <param-value>AUTO</param-value>
    </init-param>
</filter>
<!-- Include this if you are using Hibernate -->
<filter-mapping>
    <filter-name>OpenEntityManagerInViewFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

<!-- Spring config -->
<listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<listener>
    <listener-class>org.springframework.web.context.request.RequestContextListener</listener-class>
</listener>

applicationContext.xml：

<bean id="entityManagerFactory"
    class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
    <property name="jpaVendorAdapter">
        <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter" />
    </property>
    <property name="jpaProperties">
        <props>
            <prop key="hibernate.transaction.manager_lookup_class">
                org.hibernate.transaction.JBossTransactionManagerLookup
            </prop>
        </props>
    </property>
</bean>

persistence.xml：

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0"
   xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="
        http://java.sun.com/xml/ns/persistence
        http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
   <persistence-unit name="primary">
      <!-- If you are running in a production environment, add a managed 
         data source, the example data source is just for proofs of concept! -->
      <jta-data-source>java:jboss/datasources/ExampleDS</jta-data-source>
      <properties>
         <!-- Properties for Hibernate -->
         <property name="hibernate.hbm2ddl.auto" value="create-drop" />
         <property name="hibernate.show_sql" value="false" />
      </properties>
   </persistence-unit>
</persistence>

这基本上就是所有的设置。除了延迟加载问题之外，一切正常。

Answer 1

需要在初始化参数EntityManager中注明

<filter>
    <filter-name>
        OpenEntityManagerInViewFilter
    </filter-name>
    <filter-class>
        org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter
    </filter-class>
    <init-param>
        <param-name>entityManagerFactoryBeanName</param-name>
        <param-value>entityManagerFactory</param-value>
    </init-param>
    <init-param>
        <param-name>flushMode</param-name>
        <param-value>AUTO</param-value>
    </init-param>
</filter>

Answer 2

确保您不访问旧实体（例如，之前请求中的会话中的序列化实体）。