Spring中bean注入前后的一些操作：

InitializingBean 和 DisposableBean

init-method 和 destroy-method

@PostConstruct 和 @PreDestroy

In Spring, InitializingBean and DisposableBean are two marker interfaces, a useful way for Spring to perform certain actions upon bean initialization and destruction.

1. For bean implemented InitializingBean, it will run afterPropertiesSet() after all bean properties have been set.
2. For bean implemented DisposableBean, it will run destroy() after Spring container is released the bean.

In Spring, you can use init-method and destroy-method as attribute in bean configuration file for bean to perform certain actions upon initialization and destruction.

Note
The @PostConstruct and @PreDestroy annotation are not belong to Spring, it’s located in the J2ee library – common-annotations.jar.

具体的使用

对于第一个：

import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
 
public class CustomerService implements InitializingBean, DisposableBean
{
	String message;
 
	public String getMessage() {
	  return message;
	}
 
	public void setMessage(String message) {
	  this.message = message;
	}
 
	public void afterPropertiesSet() throws Exception {
	  System.out.println("Init method after properties are set : " + message);
	}
 
	public void destroy() throws Exception {
	  System.out.println("Spring Container is destroy! Customer clean up");
	}
 
}

　　下面的例子展示了 init-method and destroy-method.

public class CustomerService
{
	String message;
 
	public String getMessage() {
	  return message;
	}
 
	public void setMessage(String message) {
	  this.message = message;
	}
 
	public void initIt() throws Exception {
	  System.out.println("Init method after properties are set : " + message);
	}
 
	public void cleanUp() throws Exception {
	  System.out.println("Spring Container is destroy! Customer clean up");
	}
 
}

　　

<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-2.5.xsd">
 
	<bean id="customerService" class="com.mkyong.customer.services.CustomerService" 
		init-method="initIt" destroy-method="cleanUp">
 
		<property name="message" value="i'm property message" />
	</bean>
 
</beans>

　　第三种的使用：

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
 
public class CustomerService
{
	String message;
 
	public String getMessage() {
	  return message;
	}
 
	public void setMessage(String message) {
	  this.message = message;
	}
 
	@PostConstruct
	public void initIt() throws Exception {
	  System.out.println("Init method after properties are set : " + message);
	}
 
	@PreDestroy
	public void cleanUp() throws Exception {
	  System.out.println("Spring Container is destroy! Customer clean up");
	}
 
}

　　By default, Spring will not aware of the @PostConstruct and @PreDestroy annotation. To enable it, you have to either register ‘CommonAnnotationBeanPostProcessor‘ or specify the ‘<context:annotation-config />‘ in bean configuration file,

1. CommonAnnotationBeanPostProcessor

<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-2.5.xsd">
 
	<bean class="org.springframework.context.annotation.CommonAnnotationBeanPostProcessor" />
 
	<bean id="customerService" class="com.mkyong.customer.services.CustomerService">
		<property name="message" value="i'm property message" />
	</bean>
 
</beans>

　　

2. <context:annotation-config />

<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="http://www.springframework.org/schema/beans
	http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
	http://www.springframework.org/schema/context
	http://www.springframework.org/schema/context/spring-context-2.5.xsd">
 
	<context:annotation-config />
 
	<bean id="customerService" class="com.mkyong.customer.services.CustomerService">
		<property name="message" value="i'm property message" />
	</bean>
 
</beans>