java - Spring JPA/Hibernate EmptyInterceptor 不注入(inject) Entitymanager/Spring beans

Question

专家/大师/ friend

我们正在使用 Spring 3.2、JPA 2、Hibernate 4.2 组合，并在尝试将任何带有 Spring 注解的 bean 注入(inject)到实现如下所示的 EmtyInterceptor 时面临这个奇怪的空指针问题。我们尝试过注释这个 bean 以及 spring bean，但没有成功。

非常感谢任何帮助解决这个难题的人。

import javax.inject.Inject;
import javax.inject.Named;
import org.hibernate.EmptyInterceptor;
import org.hibernate.type.Type;
import org.springframework.transaction.annotation.Transactional;
...

@Named
@Transactional
public class AuditEmptyInterceptor extends EmptyInterceptor {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    // Didnt inject - Null
    @PersistenceContext
    private EntityManager entityManager;

    // Didnt inject - Null
    //@PersistenceUnit
    //private EntityManagerFactory entityManagerFactory;

    // Didnt inject - Null
    //@Inject
    //private AuditHelper auditHelper;

    @Override
    public boolean onSave(Object entity, Serializable id, Object[] currentState,
            String[] propertyNames, Type[] types) {

        System.out.println("**********inside OnSave() in Audit Empty Interceptor******************");
        if(entity instanceof xxAuditInterface || entity instanceof xxxCompBranchInterface){
            for (int i = 0; i < propertyNames.length; i++) {
         ...
         ...
         // Null entityManager - NPE here
        javax.persistence.Query query = entityManager.createQuery("Select c From CompanyDO c Where c.companyName =:companyName");
        query.setParameter("companyName", xxx);
        CompanyMasterDO companyMasterDO = (CompanyMasterDO) query.getSingleResult();
         ...
         ...
          }
         }
        }

 }

在应用程序的其他地方，注入(inject)工作就像一个魅力，没有任何问题。这是我们的 applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans default-lazy-init="true" 
xmlns="http://www.springframework.org/schema/beans" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xmlns:p="http://www.springframework.org/schema/p"
xmlns:aop="http://www.springframework.org/schema/aop" 
xmlns:context="http://www.springframework.org/schema/context"
xmlns:jee="http://www.springframework.org/schema/jee" 
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:util="http://www.springframework.org/schema/util"
xmlns:sec="http://www.springframework.org/schema/security"
xmlns:task="http://www.springframework.org/schema/task"
xsi:schemaLocation="
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd
        http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.2.xsd
        http://www.springframework.org/schema/security http://www.springframework.org/schema/security/spring-security-3.1.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd
        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
        http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-3.2.xsd
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.2.xsd">


<context:annotation-config></context:annotation-config> 

<context:component-scan base-package="com" />

<context:property-placeholder location="classpath*:hibernate.properties" />
<tx:annotation-driven />

<bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
    <property name="dataSource" ref="dataSource" />
    <property name="packagesToScan" value="com"/>
 </bean>

<bean id="dataSource"
    class="org.springframework.jdbc.datasource.DriverManagerDataSource"
    p:driverClassName="com.mysql.jdbc.Driver" p:url="jdbc:mysql://localhost/rcent_rel_2"
    p:username="root" p:password="root" />

<bean id="entityManagerFactory"
    class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"
    p:dataSource-ref="dataSource" p:jpaVendorAdapter-ref="jpaAdapter">
    <property name="loadTimeWeaver">
        <bean
            class="org.springframework.instrument.classloading.InstrumentationLoadTimeWeaver" />
    </property>
    <property name="persistenceXmlLocation" value="classpath*:META-INF/spring-persistence.xml" />
</bean>

<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"
    p:entityManagerFactory-ref="entityManagerFactory" />

<bean id="jpaAdapter"
    class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"
    p:database="MYSQL" 
    p:showSql="false" 
    p:databasePlatform="org.hibernate.dialect.MySQL5Dialect"/>

<\beans>

我们的 spring-persistence.xml 如下。请注意，我在这里添加了 Emptyinceptor 属性。

<?xml version="1.0" encoding="UTF-8"?>

<persistence 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" version="2.0">
<persistence-unit name="xxx" transaction-type="RESOURCE_LOCAL">
    <class>com.xxx</class>
         ...
         ...
    <properties>
           <property name="hibernate.ejb.interceptor"
                       value="com.company.demo.audit.AuditEmptyInterceptor" />           
    </properties>
    </persistence-unit>
</persistence>

让我知道您对此的宝贵想法/提示。再次感谢您花时间阅读这篇文章。

我也读过这篇文章Injecting JPA's Entity Manager in Hibernate's EmptyInterceptor 。但看起来他们正在手动尝试找到具有名称的 bean 来解析，我觉得可能还有其他方法。

Answer 1

AuditEmptyInterceptor 不是 Spring 管理的 bean，它是由 Hibernate 实例化的，因此您无法向其中注入(inject)依赖项。

您可以使用静态委托(delegate)来代替:

public class StaticDelegateInterceptor extends EmptyInterceptor {

    private static Interceptor interceptor; 

    public static void setInterceptor(Interceptor interceptor) {
        StaticDelegate.interceptor = interceptor;
    }

    public boolean onSave(Object entity, Serializable id, Object[] state, String[] propertyNames, Type[] types) {
      return StaticDelegate.interceptor.onSave(entity, id, state, propertyNames, types);
    }
    ...
}

在persistence.xml上注册StaticDelegateInterceptor

<persistence>
    <persistence-unit name="xxx" transaction-type="RESOURCE_LOCAL">
       <class>com.xxx</class>
       ...
       ...
       <properties>
          <property name="hibernate.ejb.interceptor"
                   value="com.company.demo.audit.StaticDelegateInterceptor" />           
       </properties>
   </persistence-unit>
</persistence>

修改当前的 AuditEmptyInterceptor 以便它向 StaticDelegateInterceptor 注册自身:

@Named
@Transactional
public class AuditEmptyInterceptor extends EmptyInterceptor {  

     @PostConstruct
     public void init() {
          StaticDelagateInterceptor.setInterceptor(this);
     }
     ...
}

最后通过设置depends-on属性来确保您的entityManagerFactory bean依赖于您的auditEmptyInterceptor:

<bean id="entityManagerFactory"
class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"
p:dataSource-ref="dataSource" p:jpaVendorAdapter-ref="jpaAdapter"
depends-on="auditEmptyInterceptor" >
...
</bean>