Spring Bean Life Cycleby Pigbrain

Overview of Spring Bean Life Cycle

Java Object
- new operator를 호출함으로써 객체가 생성된다
- gc에 의하여 finalize()가 호출되고 사라진다
Spring Bean
- InitializingBean, DisposableBean
  - Bean 생성 / 삭제시 호출되는 콜백 인터페이스
- BeanNameAware, BeanFactoryAware, ApplicationContextAware Interface
  - 특수한 작업을 위한 인터페이스
- configuration file
  - custom init(), destroy()
- Annotation
  - @PostConstruct, @PreDestroy
Bean의 초기화부터 사용 전까지의 과정

BeanPostProcessor를 구현하게 되면 lazy-init 속성은 무시된다
Bean의 삭제 과정

InitializingBean and DisposbleBean callback interfaces

org.springframework.beans.factory.InitalizingBean
- void afterPropertiesSet() throws Exception;
org.springframework.beans.factory.DisposableBean
- void destroy() throws Exception;

Example

import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;

public class PersonBean implements InitializingBean,DisposableBean{
 
	private String name;

	public PersonBean() {
		System.out.println("Constructor of person bean is called !! ");
	}
	
	@Override
	public void destroy() throws Exception {
		System.out.println("destroy method of person bean is called !! ");
	}

	@Override
	public void afterPropertiesSet() throws Exception {
		System.out.println("afterPropertiesSet method of person bean is called !! ");
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}
}  

Bean Name, Factory, Application context Aware interfaces

org.springframework.beans.factory.BeanFactoryAware
- void setBeanFactory(BeanFactory beanFactory) throws BeansException;
org.springframework.beans.factory.BeanNameAware
- void setBeanName(String name);
org.springframework.context.ApplicationContextAware
- void setApplicationContext(ApplicationContext applicationContext) throws BeansException;

Example

import java.util.Arrays;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.BeanNameAware;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
 
public class AwareBean implements ApplicationContextAware,BeanNameAware,BeanFactoryAware {
	
	@Override
	public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
		System.out.println("setBeanFactory method of Aware bean is called");
		System.out.println("setBeanFactory:: Aware bean singleton="                + beanFactory.isSingleton("awareBean"));
	}

	@Override
	public void setBeanName(String beanName) {
		System.out.println("setBeanName method of Aware bean is called");
		System.out.println("setBeanName:: Bean Name defined in context=" +  beanName);
	}

	@Override
	public void setApplicationContext(ApplicationContext applicationContext)   throws BeansException {
		System.out.println("setApplicationContext method of Aware bean is called");
		System.out.println("setApplicationContext:: Bean Definition Names=" 		+ Arrays.toString(applicationContext.getBeanDefinitionNames()));
	}
}  

Custom init() and destroy() methods in bean configuration file

Attribute
- init-method
- destroy-method

Example

<bean id="customLifeCycleMethodBean" class="CustomLifeCycleMethodBean"
	init-method="customInit" 
	destroy-method="customDestroy">
	<property name="name" value="custom methods bean" ></property>
</bean>

-----------------------------------------------------------------------

public class CustomLifeCycleMethodBean {
	private String name;
     
    public CustomLifeCycleMethodBean() {
		System.out.println("Constructor of  bean is called !! ");
    }
     
    public void customDestroy() throws Exception {
		System.out.println("custom destroy method of  bean is called !! ");
    }
 
    public void customInit() throws Exception {
		System.out.println("custom Init  method of  bean is called !! ");
    }
 
    public String getName() {
		return name;
    }
 
    public void setName(String name) {
		this.name = name;
    }
}  

원문

http://www.wideskills.com/spring/spring-bean-lifecycle

Published 04 March 2016

Spring