Spring 允许在 Bean 在初始化完成后以及 Bean 销毁前执行特定的操作,常用的设定方式有以下三种:
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通过Bean实现 InitializingBean/DisposableBean 接口来定制初始化之后/销毁之前的操作方法;【缺点:要依赖Spring】
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通过 <bean> 元素的 init-method/destroy-method属性指定初始化之后 /销毁之前调用的操作方法;(也可以不是xml配置,而是在@Bean上注解,效果相同)【优点:不依赖于Spring的接口】
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在指定方法上加上@PostConstruct 或@PreDestroy 注解来制定该方法是在初始化之后还是销毁之前调用【在servlet中,要考虑的执行流程是:servlet构造函数 > PostConstruct > init() > service() > destory() > PreDestroy】
注意:子类实例化过程中会调用父类中的@PostConstruct方法!
但他们之前并不等价。即使3个方法都用上了,也有先后顺序.
Bean在实例化的过程中:Constructor > @PostConstruct >InitializingBean > init-method
Bean在销毁的过程中:@PreDestroy > DisposableBean > destroy-method
import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class InitAndDestroySeqBean implements InitializingBean,DisposableBean {
public InitAndDestroySeqBean(){
System.out.println("执行InitAndDestroySeqBean: 构造方法");
}
@PostConstruct
public void postConstruct() {
System.out.println("执行InitAndDestroySeqBean: postConstruct");
}
@Override
public void afterPropertiesSet() throws Exception {
System.out.println("执行InitAndDestroySeqBean: afterPropertiesSet");
}
public void initMethod() {
System.out.println("执行InitAndDestroySeqBean: init-method");
}
@PreDestroy
public void preDestroy() {
System.out.println("执行InitAndDestroySeqBean: preDestroy");
}
@Override
public void destroy() throws Exception {
System.out.println("执行InitAndDestroySeqBean: destroy");
}
public void destroyMethod() {
System.out.println("执行InitAndDestroySeqBean: destroy-method");
}
public static void main(String[] args) {
ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("com/chj/spring/bean.xml");
context.close();
}
}
<?xml version="1.0" encoding="UTF-8"?>
<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="initAndDestroySeqBean" class="com.chj.spring.InitAndDestroySeqBean" init-method="initMethod" destroy-method="destroyMethod"/>
</beans>
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