Use Spring annotations to automatically apply Hibernate Interceptor?

Question

In my service class I need the hibernate session available. I currently do this in the beans.xml:

<bean id = "userDao" class="org.springframework.aop.framework.ProxyFactoryBean">
 <property name="target">
   <ref bean="userDaoTarget" />
 </property>

 <property name="proxyInterfaces">
   <value>com.app.dao.UserDao</value>
 </property>

 <property name="interceptorNames">
   <list>
     <value>hibernateInterceptor</value>
   </list>
 </property>

 <qualifier value="proxy" />
</bean>

...

<bean id="hibernateInterceptor" 
   class="org.springframework.orm.hibernate3.HibernateInterceptor">
 <property name="sessionFactory">
   <ref bean="sessionFactory" />
 </property>
<bean>

(copied by hand, may be some typos..)

I'm moving to using annotations over XML, I was wondering if there was a way to use them to configure the proxy as I have above including the hibernate interceptor? If not - is there a way that I can reduce the amount of XML (with about 7 DAOs it makes it very cluttered)

Answer 1

Have a look at the @Autowired annotation.

Answer 2

Ok, Let's go. You said

I am moving to using annotations over XML

Enable an aspect as follows

package br.com.ar.aop;

@Aspect
public class HibernateInterceptorAdvice {

     @Autowired
     private HibernateInterceptor hibernateInterceptor;

     /**
       * I suppose your DAO's live in com.app.dao package
       */
     @Around("execution(* com.app.dao.*(..))")
     public Object interceptCall(ProceedingJoinPoint joinPoint) throws Throwable {
         ProxyFactory proxyFactory = new ProxyFactory(joinPoint.getTarget());
         proxyFactory.addAdvice(hibernateInterceptor);

         Class [] classArray = new Class[joinPoint.getArgs().length];
         for (int i = 0; i < classArray.length; i++)
             classArray[i] = joinPoint.getArgs()[i].getClass();

         return
             proxyFactory
                 .getProxy()
                 .getClass()
                 .getDeclaredMethod(joinPoint.getSignature().getName(), classArray)
                 .invoke(proxyFactory.getProxy(), joinPoint.getArgs());
     }

}

But keep in mind It just works if your DAO's implements some interface (For instance, UserDAOImpl implements UserDAO). Spring AOP uses JDK dynamic proxy in this case. If you does not have any interface, you can rely on your IDE To refactor your code by using Extract interface

Declare your xml as follows (Be aware i am using Spring 2.5 xsd schema)

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" 
    xmlns:aop="http://www.springframework.org/schema/aop" 
    xmlns:context="http://www.springframework.org/schema/context" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    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-2.5.xsd 
                        http://www.springframework.org/schema/aop  
                        http://www.springframework.org/schema/aop/spring-aop-2.5.xsd"&gt;
    <!--SessionFactory settings goes here-->
    <bean class="org.springframework.orm.hibernate3.HibernateInterceptor">
        <property name="sessionFactory" ref="sessionFactory"/>
    <bean>
    <!--To enable AspectJ AOP-->
    <aop:aspectj-autoproxy/>
    <!--Your advice-->
    <bean class="br.com.ar.aop.HibernateInterceptorAdvice"/>
    <!--Looks for any annotated Spring bean in com.app.dao package-->
    <context:component-scan base-package="com.app.dao"/>
    <!--Enables @Autowired annotation-->
    <context:annotation-config/>
</beans>

Do not forget To put in the classpath besides Spring libraries

<SPRING_HOME>/lib/asm
<SPRING_HOME>/lib/aopalliance
<SPRING_HOME>/lib/aspectj