Spring注解@PostConstruct与@PreDestroy
关于在spring 容器初始化 bean 和销毁前所做的操作定义方式有三种:
第一种:通过@PostConstruct 和 @PreDestroy 方法 实现初始化和销毁bean之前进行的操作 第二种是:通过 在xml中定义init-method 和 destory-method方法 第三种是: 通过bean实现InitializingBean和 DisposableBean接口
下面演示通过 @PostConstruct 和 @PreDestory
第一种:
1:定义相关的实现类:
package com.myapp.core.annotation.init; import javax.annotation.PostConstruct; import javax.annotation.PreDestroy; public class PersonService { private String message; public String getMessage() { return message; } public void setMessage(String message) { this.message = message; } @PostConstruct public void init(){ System.out.println("I'm init method using @PostConstrut...."+message); } @PreDestroy public void dostory(){ System.out.println("I'm destory method using @PreDestroy....."+message); } }
2:定义相关的配置文件:
<?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-3.1.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd"> <!-- <context:component-scan base-package="com.myapp.core.jsr330"/> --> <context:annotation-config /> <bean id="personService" class="com.myapp.core.annotation.init.PersonService"> <property name="message" value="123"></property> </bean> </beans>
其中<context:annotation-config />告诉spring 容器采用注解配置:扫描注解配置;
测试类:
package com.myapp.core.annotation.init; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class MainTest { public static void main(String[] args) { ApplicationContext context = new ClassPathXmlApplicationContext("resource/annotation.xml"); PersonService personService = (PersonService)context.getBean("personService"); personService.dostory(); } }
测试结果:
I'm init method using @PostConstrut....123 I'm destory method using @PreDestroy.....123
其中也可以通过申明加载org.springframework.context.annotation.CommonAnnotationBeanPostProcessor
类来告诉Spring容器采用的 常用 注解配置的方式:
只需要修改配置文件为:
<?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-3.1.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd"> <!-- <context:component-scan base-package="com.myapp.core.jsr330"/> --> <!-- <context:annotation-config /> --> <bean class="org.springframework.context.annotation.CommonAnnotationBeanPostProcessor" /> <bean id="personService" class="com.myapp.core.annotation.init.PersonService"> <property name="message" value="123"></property> </bean> </beans>
同样可以得到以上测试的输出结果。
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第二种:
1:在xml中配置 init-method和 destory-method方法
只是定义spring 容器在初始化bean 和容器销毁之前的所做的操作基于xml的配置只是一种方式:
直接上xml中配置文件:
<bean id="personService" class="com.myapp.core.beanscope.PersonService" scope="singleton" init-method="init" destroy-method="cleanUp"> </bean>
定义PersonService类:
package com.myapp.core.beanscope; public class PersonService { private String message; public String getMessage() { return message; } public void setMessage(String message) { this.message = message; } public void init(){ System.out.println("init"); } // how validate the destory method is a question public void cleanUp(){ System.out.println("cleanUp"); } }
相应的测试类:
package com.myapp.core.beanscope; import org.springframework.context.support.AbstractApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class MainTest { public static void main(String[] args) { AbstractApplicationContext context =new ClassPathXmlApplicationContext("SpringBeans.xml"); PersonService person = (PersonService)context.getBean("personService"); person.setMessage("hello spring"); PersonService person_new = (PersonService)context.getBean("personService"); System.out.println(person.getMessage()); System.out.println(person_new.getMessage()); context.registerShutdownHook(); } }
测试结果:
init
hello spring
hello spring
cleanUp
可以看出 init 方法和 clean up方法都已经执行了。
context.registerShutdownHook(); 是一个钩子方法,当jvm关闭退出的时候会调用这个钩子方法,在设计模式之 模板模式中 通过在抽象类中定义这样的钩子方法由实现类进行实现,这里的实现类是AbstractApplicationContext,这是spring 容器优雅关闭的方法。
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第三种:
1:定义相应类实现InitializingBean ,DisposableBean 接口
package com.myapp.core.annotation.init; import javax.annotation.PostConstruct; import javax.annotation.PreDestroy; import org.springframework.beans.factory.DisposableBean; import org.springframework.beans.factory.InitializingBean; public class PersonService implements InitializingBean,DisposableBean{ private String message; public String getMessage() { return message; } public void setMessage(String message) { this.message = message; } @Override public void destroy() throws Exception { // TODO Auto-generated method stub System.out.println("I'm init method using implements InitializingBean interface...."+message); } @Override public void afterPropertiesSet() throws Exception { // TODO Auto-generated method stub System.out.println("I'm init method using implements DisposableBean interface...."+message); } }
2:定义相应的配置文件:
<?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-3.1.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd"> <!-- <context:component-scan base-package="com.myapp.core.jsr330"/> --> <!-- <context:annotation-config /> --> <!-- <bean class="org.springframework.context.annotation.CommonAnnotationBeanPostProcessor" /> <bean id="personService" class="com.myapp.core.annotation.init.PersonService"> <property name="message" value="123"></property> </bean> --> <bean id="personService" class="com.myapp.core.annotation.init.PersonService"> <property name="message" value="123"></property> </bean> </beans>
3:测试类:
package com.myapp.core.annotation.init; import org.springframework.context.ApplicationContext; import org.springframework.context.support.AbstractApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class MainTest { public static void main(String[] args) { AbstractApplicationContext context = new ClassPathXmlApplicationContext("resource/annotation.xml"); PersonService personService = (PersonService)context.getBean("personService"); context.registerShutdownHook(); } }
4:输出测试结果:
I'm init method using implements DisposableBean interface....123 三月 16, 2013 5:06:34 下午 org.springframework.context.support.AbstractApplicationContext doClose INFO: Closing org.springframework.context.support.ClassPathXmlApplicationContext@205756: startup date [Sat Mar 16 17:06:30 CST 2013]; root of context hierarchy I'm init method using implements InitializingBean interface....123
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