Hibernate Interceptor

Hibernate Interceptor
By implementing Hibernate Interceptor interface or by implementing org.hibernate.classic.Validatable or by implementing org.hibernate.classic.Lifecycle , you can receive the various callbacks from a hibernate "session".

Using these callbacks you could inspect persistent objects before they are saved, deleted, updated or loaded.

1. Interceptor Approach
   

• Interceptor could be done at a session scope or at session factory level or at persistent class level.
  
• If its done at session factory level, interceptors must be thread safe, taking care to not store session-specific state since multiple sessions will use this interceptor (potentially) concurrently.
• At session level, one instance per session.
• To implement a Interceptor 2 ways
• Implement interface org.hibernate.Interceptor
• Or extend org.hibernate.EmptyInterceptor
• Once interceptor is implemented register it programatically with session or session factory
• Register the interceptor with Session
  

Session session = sf.openSession( new MyInterceptor());

• Register the interceptor with SessionFactory

new Configuration().setInterceptor( new MyInterceptor() );

• Integration with spring ?
  

<bean id="myInterceptor" class="com.company.MyInterceptor"/>
<bean id="sessionFactory" class="org.springframework.orm.hibernate.LocalSessionFactoryBean">
<property name="entityInterceptor">
<ref bean="myInterceptor">
</ref>
</property></bean>

• Pros & cons

• Gives flexibility to do things at session and/or at entire application level.
• Could be a bottleneck if interceptor is being used at SessionFactory level, code inside interceptor has to be written very-2 carefully to make sure it is efficient. --- Things we may end up doing are logging changes to specific database tables in a database or to a log file(files is not a good idea).
• Would be nice if the interceptors could turned on and off based on configuration files, instead of programatically enabling it.? --- This could be achieved by modifying SPRING configuration file.(applicationContext.xml)
• To log for specific list of persistence entities there is no out of box configuration, one would have to create additional configuration parameters ?