Spring - How to call a method after bean initialization is complete?

Question

Hi,

I have a use case where I need to call a (non-static) method in the bean only-once at the ApplicationContext load up. Is it ok, if I use MethodInvokingFactoryBean for this? Or we have a some better solution?

As a side note, I use ConfigContextLoaderListener to load the Application Context in web application. And want, that if bean 'A' is instantiated just call methodA() once.

How can this be done nicely?

Answer 1

Have you tried implementing InitializingBean? It sounds like exactly what you're after.

The downside is that your bean becomes Spring-aware, but in most applications that's not so bad.

Answer 2

You could deploy a custom BeanPostProcessor in your application context to do it. Or if you don't mind implementing a Spring interface in your bean, you could use the InitializingBean interface or the "init-method" directive (same link).

Answer 3

You can use something like:

<beans>
    <bean id="myBean" class="..." init-method="init"/>
</beans>

This will call the "init" method when the bean is instantiated.

Answer 4

Three different approaches to consider as described in the reference

(1) Use init-method attribute.

Pros - does not require bean to implement an interface.

(2) Implement InitializingBean.

Cons - more invasive than the init-method approach.

(3) Use JSR-250 @PostConstruct lifecyle annotation.

Pros:

Useful when using component scanning to autodetect beans.

Makes it clear that a specific method is to be used for initialisation

Cons:

Initialisation no longer centrally specified in configuration. Now scattered throughout code.

Answer 5

To expand on the @PostConstruct suggestion in other answers, this really is the best solution, in my opinion.

• It keeps your code decoupled from the Spring API (@PostConstruct is in javax.*)
• It explicitly annotates your init method as something that needs to be called to initialize the bean
• Your class can have as many @PostConstruct and @PreDestroy-annotated methods as you like.
• You don't need to remember to add the init-method attribute to your spring bean definition, spring will automatically call the method (assuming you register the annotation-config option somewhere else in the context, anyway).