CODEWITHSUNDEEP
springinitializationstartupapplicationcontext
peakit
peakit

Reputation: 29349

How to call a method after bean initialization is complete?

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?

Upvotes: 280

Views: 387832

Answers (6)

Jon Skeet
Jon Skeet

Reputation: 1499840

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.

Upvotes: 42

toolkit
toolkit

Reputation: 50227

There are three different approaches to consider, as described in the reference

Use init-method attribute

Pros:

  • Does not require bean to implement an interface.

Cons:

  • No immediate indication in source code that this method is required after construction to ensure the bean is correctly configured.

Implement InitializingBean

Pros:

  • No need to specify init-method, or turn on component scanning / annotation processing.
  • Appropriate for beans supplied with a library, where we don't want the application using this library to concern itself with bean lifecycle.

Cons:

  • More invasive than the init-method approach.

Use JSR-250 @PostConstruct lifecyle annotation

Pros:

  • Useful when using component scanning to autodetect beans.
  • Makes it clearer that a specific method is to be used for initialisation. Intent is closer to the code.

Cons:

  • Initialisation no longer centrally specified in configuration.
  • You must remember to turn on annotation processing (which can sometimes be forgotten)

Upvotes: 116

skaffman
skaffman

Reputation: 403441

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
  • 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).

Upvotes: 359

Ayorinde
Ayorinde

Reputation: 15

To further clear any confusion about the two approach i.e use of

  1. @PostConstruct and
  2. init-method="init"

From personal experience, I realized that using (1) only works in a servlet container, while (2) works in any environment, even in desktop applications. So, if you would be using Spring in a standalone application, you would have to use (2) to carry out that "call this method after initialization.

Upvotes: -9

Mercer Traieste
Mercer Traieste

Reputation: 4678

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.

Upvotes: 209

Rob H
Rob H

Reputation: 14952

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).

Upvotes: 8

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