Hooking to bean life cycles

Often, in enterprise application development, developers will want to plug in some extra functionality to be executed just after the construction and before the destruction of a business service. Spring provides multiple methods for interacting with such stages in the life cycle of a bean.

Implementing InitializingBean and DisposableBean

The Spring IoC container invokes the callback methods afterPropertiesSet() of org.springframework.beans.factory.InitializingBean and destroy() of org.springframework.beans.factory.DisposableBean on any Spring bean and implements them:

public class UserServiceImpl implements UserService, InitializingBean, DisposableBean {
...
   @Override
   public void afterPropertiesSet() throws Exception {
      logger.debug(this + ".afterPropertiesSet() invoked!");
      // Your initialization code goes here..
   }

   @Override
   public void destroy() throws Exception {
      logger.debug(this + ".destroy() invoked!");
      // Your cleanup code goes here..
   }
...
}

Annotating @PostConstruct and @PreDestroy on @Components

Spring supports JSR 250 @PostConstruct and @PreDestroy annotations on any Spring bean in an annotation-supported environment, as shown here. Spring encourages this approach over implementing Spring-specific interfaces, as given in the previous section:

@Service
public class AnnotatedTaskService implements TaskService {
...
   @PostConstruct
   public void init() {
      logger.debug(this.getClass().getName() + " started!");
   }

   @PreDestroy
   public void cleanup() {
      logger.debug(this.getClass().getName() + " is about to destroy!");
   }
...
}

The init-method and destroy-method attributes of <bean/>

If you are using XML-only bean configuration metadata, then your best option is to declare init-method and destroy-method attributes on your <bean/> tags:

<bean id="xmlTaskService" class="com...XmlDefinedTaskService" init-method="init" destroy-method="cleanup">
...
</bean>