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从BeanFactory源码看Bean的生命周期( 七 )

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所以，看起来 ， 整个Bean的销毁步骤都是这哥们儿一个人完成的喽 。

从BeanFactory源码看Bean的生命周期

文章插图
不过这个图应该画错了，它把DestructionAwareBeanPostProcessors写成了InstantiationAwareBeanPostProcessor 。
看看它被调用的构造方法里写了啥：
public DisposableBeanAdapter(Object bean, String beanName, RootBeanDefinition beanDefinition,List<DestructionAwareBeanPostProcessor> postProcessors, @Nullable AccessControlContext acc) {this.bean = bean;this.beanName = beanName;this.nonPublicAccessAllowed = beanDefinition.isNonPublicAccessAllowed();// 该Bean是不是可调用的DisposableBeanthis.invokeDisposableBean = (bean instanceof DisposableBean &&!beanDefinition.hasAnyExternallyManagedDestroyMethod(DESTROY_METHOD_NAME));// destroy方法名String destroyMethodName = inferDestroyMethodIfNecessary(bean, beanDefinition);// 和初始化哪里一样，防止destroy方法名和DisposableBean的方法名一样，重复调用if (destroyMethodName != null &&!(this.invokeDisposableBean && DESTROY_METHOD_NAME.equals(destroyMethodName)) &&!beanDefinition.hasAnyExternallyManagedDestroyMethod(destroyMethodName)) {// 如果Bean是一个AutoClosable并且自定义的销毁方法名也是close的话this.invokeAutoCloseable = (bean instanceof AutoCloseable && CLOSE_METHOD_NAME.equals(destroyMethodName));if (!this.invokeAutoCloseable) {// 如果不是 ， destroyMethodName就使用用户指定的并解析对应方法this.destroyMethodName = destroyMethodName;Method destroyMethod = determineDestroyMethod(destroyMethodName);// 省略一些destroy method参数设置相关的代码this.destroyMethod = destroyMethod;}}// 获取beanPostProcessors（filterPostProcessors会过滤掉所有非DestructionAwareBeanPostProcessor的类）this.beanPostProcessors = filterPostProcessors(postProcessors, bean);this.acc = acc;}这里就是做了一些初始化工作，把需要的成员变量都解析出来，方便后面destroy时使用 。
然后我们看看destroy方法：
public void destroy() {// 调用所有DestructionAwareBeanPostProcessor的postProcessBeforeDestructionif (!CollectionUtils.isEmpty(this.beanPostProcessors)) {for (DestructionAwareBeanPostProcessor processor : this.beanPostProcessors) {processor.postProcessBeforeDestruction(this.bean, this.beanName);}}// 如果是一个disposableBean，调用它的destroyif (this.invokeDisposableBean) {((DisposableBean) this.bean).destroy();}// 如果是AutoCloseable（并且自定义销毁方法名也是close） ， 直接调用closeif (this.invokeAutoCloseable) {((AutoCloseable) this.bean).close();}// 否则去调用自定义方法else if (this.destroyMethod != null) {invokeCustomDestroyMethod(this.destroyMethod);}// 有可能存在destroyMethod没解析，但是destroyMethodName有了的情况，解析并调用else if (this.destroyMethodName != null) {Method destroyMethod = determineDestroyMethod(this.destroyMethodName);if (destroyMethod != null) {invokeCustomDestroyMethod(ClassUtils.getInterfaceMethodIfPossible(destroyMethod, this.bean.getClass()));}}}实战DestructionAwareBeanPostProcessor#创建DestructionAwareBeanPostProcessor
public class MyDestructionProcessor implements DestructionAwareBeanPostProcessor {@Overridepublic void postProcessBeforeDestruction(Object bean, String beanName) throws BeansException {System.out.println("[+] DestructionProcessor : " + beanName);}}向工厂中添加BeanPostProcessor，并销毁Bean：
factory.addBeanPostProcessor(new MyDestructionProcessor());factory.destroyBean("workbench", workbench);结果：
Workbench(operator=Person(name=Yudoge))[+] DestructionProcessor : top.yudoge.springserials.basic.beanfactory.beans.Workbench实战DisposableBean#让Bean实现DisposableBean
@Datapublic class Workbench implements DisposableBean {@Autowiredprivate Person operator;@Overridepublic void destroy() throws Exception {System.out.println("DisposableBean destroy");}}结果：
Workbench(operator=Person(name=Yudoge))[+] DestructionProcessor : top.yudoge.springserials.basic.beanfactory.beans.WorkbenchDisposableBean destroy实战CustomDestroyMethod#添加自定义销毁方法
@Datapublic class Workbench implements DisposableBean {@Autowiredprivate Person operator;@Overridepublic void destroy() throws Exception {System.out.println("DisposableBean destroy");}public void customDestroyMethod() {System.out.println("Custom destroy method...");}}在BeanDefinition中定义：
workbenchRbd.setDestroyMethodName("customDestroyMethod");结果：
Workbench(operator=Person(name=Yudoge))[+] DestructionProcessor : workbenchDisposableBean destroyCustom destroy method...

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