Spring bean scopes and Spring bean life cycle

Spring Bean scopes

There are six bean scopes in spring. Two scopes are related with normal beans, these are singleton and prototype. Other three related with web-aware beans, these are request, session global session.

Singleton

Spring container creates single object instance for a bean definition.

Prototype

Spring container creates any number of object instances for a bean definition.

Request

Spring container creates bean object instance for a bean definition for each HTTP request. This scope is valid in the web-aware spring context.

Session

Spring container creates one bean object instance for a bean definition for the lifetime of a single HTTP Session. This scope is valid in the web-aware spring context.

Global session

A global Session that is shared amongst all of the various portlets that make up a single portlet web application.

Spring container creates one bean object instance for a bean definition for the lifetime of a single HTTP Session. This scope is valid in the web-aware spring context.

Spring bean life cycle

Bean Instantiation – Instantiating  the bean

Set Bean Name – by using setBeanName method

Populate properties – Injecting  bean  properties

Set Bean Factory – by using setBeanFactory method, if bean implements BeanFactoryAware

Bean Pre Initialization - by postProcesserBeforeInitialization method, if bean implements

                                     BeanFactoryAware

Bean Initalization – by using init method

Bean Post initialization – by using postProcessAfterinitalization method, if bean 
                                          implements BeanFactoryAware

Bean Ready to Use - Now the bean is ready to use

Destroy bean – by using destroy method

Sample Code:

//XML declaration

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
    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-3.0.xsd"
    default-init-method="dInitMethod"
    default-destroy-method="dDestroymethod">
      <bean id="springBean" 
          class="SpringLifeCycleMehodBean" />
</beans>

-------------------------------------------------------------
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.BeanNameAware;

public class SpringBean implements BeanFactoryAware, BeanNameAware,
{

//Member variables declaration
@Override
public void setBeanName(String arg0) {
System.out.println("Method setBeanName...");
}

@Override
public void setBeanFactory(BeanFactory arg0) throws BeansException {
System.out.println("Method setBeanFactory...");
}

@PostConstruct
public void postConstruct() 
{
System.out.println("Method postConstruct...");
}

@PreDestroy
public void preDestroy() 
{
System.out.println("Method pre Destroy...");
}

}