Spring生命周期主要是指创建、初始化和销毁。 Bean的生命周期主要由容器管理,并且可以定制Bean的初始化和销毁方式。 容器将Bean推进到其生命周期中的特定时间点,并调用定制初始化和销毁方法。
代码示例地址: https://gitee.com/coding ee/day-ST/tree/sping _ cycle life /
一初始化和销毁方式1.1指定初始化前方法和容器销毁后方法init-method destory-method
在单实例bean下定制bean的初始化和销毁方法。 容器关闭时,将调用当前bean的initMethod和destoryMethod方法。 仅在调用getBean(name )时初始化多实例bean,容器不管理多实例bean,因此在容器关闭时不会调用bean的定制初始化和销毁importorg.spring framework.beans.factory.annotation.auto wired;/* ** createdwithintellijidea.** @ author : wucj ** @ date 33602020/9/1612:58 * * @ description 3360 */@ sl F4 jpublicclasscycleone { publicclasscycleone () } { log.info ) ({}.constructor . ',this.getets。 } public void destory () (log.info ) ) }.destory . ',this.getClass ) ).getSimpleName ); }使}1.2bean实现初始化bean、分布式bean接口package com.ST.spring.cycle.bean; import lombok.extern.slf4j.slf4j; importorg.spring framework.beans.factory.disposable bean; importorg.spring framework.beans.factory.initializing bean;/* ** createdwithintellijidea.** @ author : wucj ** @ date 33602020/9/1612:58 * * @ description 3360//@ sl F4 jpublicclasscycletwoimplementsinitializingbean,disposable bean { publiccycletwo () } { log.infinficlascleticled //容器删除对象后,单击@Override public void destroy () throwsexception ) log.info ) ({}.destroy . ', this.getClass ).getsiiist ) (//对象创建和赋值完成后,@ overridepublicvoidafterpropertiesset ) throwsexception ) thi info }使用在1.3 JSR 250规则(java规范)中定义的两个注释,填充package com.ST.spring.cycle.bean; import lombok.extern.slf4j.slf4j; import javax.annotation.post construct; import javax.annotation.pre destroy;/* ** createdwithintellijidea.** @ author : wucj ** @ date 33602020/9/1612:58 * * @ description 3360//@ sl F4 jpublicclasscyclethree (publiccyclethree ) (log.info ) )…constructor…),this.getClass
this.getClass().getSimpleName()); } // 对象创建并赋值完成之后调用 @PostConstruct public void methord2() { log.info("{}...afterPropertiesSet...", this.getClass().getSimpleName()); }}bean注入到容器中:
package com.st.spring.cycle.config;import com.st.spring.cycle.bean.CycleOne;import com.st.spring.cycle.bean.CycleThree;import com.st.spring.cycle.bean.CycleTwo;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Configuration;/** * * Created with IntelliJ IDEA. * * @author: wucj * * @date: 2020/9/16 12:57 * * @description: * */@Configuration// 扫描指定包路径下的所有bean@ComponentScan("com.st.spring.cycle.bean")public class CycleConfig { /** * 自定义bean的初始化和销毁方法,在容器关闭时会调用当前bean的initMethod和destoryMethod方法 * 注意1:单实例下可以调用实例的initMethod和destoryMethod方法,多实例无法调用。 * 注意2: * @return */ @Bean(initMethod = "init",destroyMethod = "destory") // 多实例不能调用initMethod和destoryMetod方法 // @Scope("prototype") public CycleOne cycleOne(){ return new CycleOne(); } @Bean public CycleTwo cycleTwo(){ return new CycleTwo(); } @Bean public CycleThree cycleThree(){ return new CycleThree(); }}容器启动和销毁:
package com.st.spring;import com.st.spring.cycle.config.CycleConfig;import org.springframework.context.annotation.AnnotationConfigApplicationContext;/** * * Created with IntelliJ IDEA. * * @author: wucj * * @date: 2020/9/16 13:01 * * @description: bean生命周期源码跟踪与学习 * */public class CycleConfigTest { public static void main(String[] args) { // 启动容器 AnnotationConfigApplicationContext app = new AnnotationConfigApplicationContext(CycleConfig.class); /** * 注意1:单实例下自定义bean的初始化和销毁方法,在容器关闭时会调用当前bean的initMethod和destoryMethod方法 * 注意2:多实例bean 只有在调用getBean(name)时才会初始化bean,并且容器不会管理多实例bean,所以容器关闭时,不会调用bean的自定义初始化和销毁bean * @return */ // 关闭容器 app.close(); }}只有以上三种可以实现bean的自定义初始化和销毁调用;
二 后置处理器后置处理器负责在初始化方法前后调用;
接口BeanPostProcessor是bean的后置处理器,在bean初始化前、后进行方法拦截;方法1:
default Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { return bean;}调用时机:在任何初始化方法调用之前进行后置处理工作(initMethod之前、initializingBean的afterPropertiesSet初始化之前)
方法2:
default Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException { return bean;}调用时机:在任何初始化方法调用之后进行后置处理工作(initMethod之后、initializingBean的afterPropertiesSet初始化之后)
总结:单实例bean的整个生命周期都可以进行控制;
三 容器启动及BeanPostProcessor源码分析针对CycleConfigTest进行debug:以下所有断点位置都是源码的位置,请使用示例源码项目断点:下载
断点1:org/springframework/context/annotation/AnnotationConfigApplicationContext.java:89
refresh();断点2:org/springframework/context/support/AbstractApplicationContext.java:551
// Instantiate all remaining (non-lazy-init) singletons. 实例化非懒加载单例beanfinishBeanFactoryInitialization(beanFactory);断点3:org/springframework/context/support/AbstractApplicationContext.java:879
// Instantiate all remaining (non-lazy-init) singletons.beanFactory.preInstantiateSingletons();断点4:org/springframework/beans/factory/support/DefaultListableBeanFactory.java:864
getBean(beanName);断点5:org/springframework/beans/factory/support/DefaultListableBeanFactory.java:897
return doGetBean(name, null, null, false);断点6:org/springframework/beans/factory/support/AbstractBeanFactory.java:201
断点7:org/springframework/beans/factory/support/AbstractBeanFactory.java:244
断点8:org/springframework/beans/factory/support/AbstractBeanFactory.java:324
return createBean(beanName, mbd, args);断点9:org/springframework/beans/factory/support/AbstractAutowireCapableBeanFactory.java:478
断点10:org/springframework/beans/factory/support/AbstractAutowireCapableBeanFactory.java:516
Object beanInstance = doCreateBean(beanName, mbdToUse, args);断点11:org/springframework/beans/factory/support/AbstractAutowireCapableBeanFactory.java:548
断点12:org/springframework/beans/factory/support/AbstractAutowireCapableBeanFactory.java:593
populateBean(beanName, mbd, instanceWrapper); // 属性赋值exposedObject = initializeBean(beanName, exposedObject, mbd); // 初始化 断点13:org/springframework/beans/factory/support/AbstractAutowireCapableBeanFactory.java:1786 // 初始化方法调用之前wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);断点14:org/springframework/beans/factory/support/AbstractAutowireCapableBeanFactory.java:1790
// 初始化invokeInitMethods(beanName, wrappedBean, mbd);断点15:org/springframework/beans/factory/support/AbstractAutowireCapableBeanFactory.java:1798
// 初始化方法调用后wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);