在Spring中，既可以实现InitializingBean和DisposableBean接口或在bean配置文件中指定 init-method 和 destroy-method 在初始化和销毁回调函数。在这篇文章中，我们将介绍如何使用 @PostConstruct 和 @PreDestroy 注解来做同样的事情。
注：@PostConstruct和@PreDestroy 标注不属于 Spring，它是在J2EE库- common-annotations.jar。
@PostConstruct 和 @PreDestroy
一个 CustomerService Bean使用 @PostConstruct 和 @PreDestroy 注释
package com.yiibai.customer.services; 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");
} }
默认情况下，Spring不会意识到@PostConstruct和@PreDestroy注解。要启用它，要么注册“CommonAnnotationBeanPostProcessor”，要么在bean配置文件的<context:annotation-config />‘ 指定，
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.yiibai.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.yiibai.customer.services.CustomerService">
<property name="message" value="i'm property message" />
</bean> </beans>
执行结果
package com.yiibai.common; import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext; import com.yiibai.customer.services.CustomerService; public class App
{
public static void main( String[] args )
{
ConfigurableApplicationContext context =
new ClassPathXmlApplicationContext(new String[] {"Spring-Customer.xml"}); CustomerService cust = (CustomerService)context.getBean("customerService"); System.out.println(cust); context.close();
}
}
输出结果
Init method after properties are set : im property message
com.yiibai.customer.services.CustomerService@47393f
...
INFO: Destroying singletons in org.springframework.beans.factory.
support.DefaultListableBeanFactory@77158a:
defining beans [customerService]; root of factory hierarchy
Spring Container is destroy! Customer clean up
initIt()方法(@PostConstruct)被调用时，消息属性设置后 cleanUp() 方法(@PreDestroy)是在context.close()执行后被调用;