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* bean的生命周期： * bean創(chuàng)建---初始化----銷毀的過程 * 容器管理bean的生命周期； * 我們可以自定義初始化和銷毀方法；容器在bean進行到當(dāng)前生命周期的時候來調(diào)用我們自定義的初始化和銷毀方法 * * 構(gòu)造（對象創(chuàng)建） * 單實例：在容器啟動的時候創(chuàng)建對象 * 多實例：在每次獲取的時候創(chuàng)建對象\ * * BeanPostProcessor.postProcessBeforeInitialization * 初始化： * 對象創(chuàng)建完成，并賦值好，調(diào)用初始化方法。。。 * BeanPostProcessor.postProcessAfterInitialization* 銷毀： * 單實例：容器關(guān)閉的時候 * 多實例：容器不會管理這個bean；容器不會調(diào)用銷毀方法；

Car.java

package com.dym.bean;public class Car {public Car(){System.out.println("car constructor...");}public void init(){System.out.println("car ... init...");}public void destroy(){System.out.println("car ... destroy...");}}

MainConfigOfLifeCycle.class

package com.dym.config;import org.springframework.context.ApplicationListener; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.Configuration; import org.springframework.context.annotation.Scope;import com.dym.bean.Car;@Configuration public class MainConfigOfLifeCycle {//@Scope("prototype")@Bean(initMethod="init",destroyMethod="destroy")public Car car(){return new Car();}}

IOCTest_LifeCycle.class

package com.dym.test;import org.junit.Test; import org.springframework.context.annotation.AnnotationConfigApplicationContext;import com.dym.config.MainConfigOfLifeCycle;public class IOCTest_LifeCycle {@Testpublic void test01(){//1、創(chuàng)建ioc容器AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(MainConfigOfLifeCycle.class);System.out.println("容器創(chuàng)建完成...");applicationContext.getBean("car");//關(guān)閉容器applicationContext.close();}}

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* 1）、指定初始化和銷毀方法； * 通過@Bean指定init-method和destroy-method；* 2）、通過讓Bean實現(xiàn)InitializingBean（定義初始化邏輯）， * DisposableBean（定義銷毀邏輯）;* 3）、可以使用JSR250； * @PostConstruct：在bean創(chuàng)建完成并且屬性賦值完成；來執(zhí)行初始化方法 * @PreDestroy：在容器銷毀bean之前通知我們進行清理工作* 4）、BeanPostProcessor【interface】：bean的后置處理器； * 在bean初始化前后進行一些處理工作； * postProcessBeforeInitialization:在初始化之前工作 * postProcessAfterInitialization:在初始化之后工作

Cat.class

package com.dym.bean.dd;import org.springframework.beans.factory.DisposableBean; import org.springframework.beans.factory.InitializingBean; import org.springframework.stereotype.Component;@Component public class Cat implements InitializingBean,DisposableBean {public Cat(){System.out.println("cat constructor...");}@Overridepublic void destroy() throws Exception {// TODO Auto-generated method stubSystem.out.println("cat...destroy...");}@Overridepublic void afterPropertiesSet() throws Exception {// TODO Auto-generated method stubSystem.out.println("cat...afterPropertiesSet...");} }

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Dog.class

package com.dym.bean.dd;import javax.annotation.PostConstruct; import javax.annotation.PreDestroy;import org.springframework.beans.BeansException; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.context.ApplicationContext; import org.springframework.context.ApplicationContextAware; import org.springframework.stereotype.Component;@Component public class Dog implements ApplicationContextAware {//@Autowiredprivate ApplicationContext applicationContext;public Dog() {System.out.println("dog constructor...");}//對象創(chuàng)建并賦值之后調(diào)用@PostConstructpublic void init() {System.out.println("Dog....@PostConstruct...");}//容器移除對象之前@PreDestroypublic void detory() {System.out.println("Dog....@PreDestroy...");}@Overridepublic void setApplicationContext(ApplicationContext applicationContext) throws BeansException {// TODO Auto-generated method stubthis.applicationContext = applicationContext;} }

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MyBeanPostProcessor.class

package com.dym.bean.dd;import org.springframework.beans.BeansException; import org.springframework.beans.factory.config.BeanPostProcessor; import org.springframework.stereotype.Component;/*** 后置處理器：初始化前后進行處理工作* 將后置處理器加入到容器中*/ @Component public class MyBeanPostProcessor implements BeanPostProcessor {@Overridepublic Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {// TODO Auto-generated method stubSystem.out.println("postProcessBeforeInitialization..."+beanName+"=>"+bean);return bean;}@Overridepublic Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {// TODO Auto-generated method stubSystem.out.println("postProcessAfterInitialization..."+beanName+"=>"+bean);return bean;} }

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BeanPostProcessor原理

* 遍歷得到容器中所有的BeanPostProcessor；挨個執(zhí)行beforeInitialization， * 一旦返回null，跳出for循環(huán)，不會執(zhí)行后面的BeanPostProcessor.postProcessorsBeforeInitialization * * BeanPostProcessor原理 * populateBean(beanName, mbd, instanceWrapper);給bean進行屬性賦值 * initializeBean * { * applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName); * invokeInitMethods(beanName, wrappedBean, mbd);執(zhí)行自定義初始化 * applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName); *} * Spring底層對 BeanPostProcessor 的使用； * bean賦值，注入其他組件，@Autowired，生命周期注解功能，@Async,xxx BeanPostProcessor;

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總結(jié)

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