Spring-Bean的销毁

Bean的销毁

public abstract class AbstractBeanFactory extends FactoryBeanRegistrySupport implements ConfigurableBeanFactory {/*** Add the given bean to the list of disposable beans in this factory,* registering its DisposableBean interface and/or the given destroy method* to be called on factory shutdown (if applicable). Only applies to singletons.* @param beanName the name of the bean* @param bean the bean instance* @param mbd the bean definition for the bean* @see RootBeanDefinition#isSingleton* @see RootBeanDefinition#getDependsOn* @see #registerDisposableBean* @see #registerDependentBean*/protected void registerDisposableBeanIfNecessary(String beanName, Object bean, RootBeanDefinition mbd) {AccessControlContext acc = (System.getSecurityManager() != null ? getAccessControlContext() : null);if (!mbd.isPrototype() && requiresDestruction(bean, mbd)) {if (mbd.isSingleton()) {// Register a DisposableBean implementation that performs all destruction// work for the given bean: DestructionAwareBeanPostProcessors,// DisposableBean interface, custom destroy method.// 销毁的Bean就是这里存进Map中的registerDisposableBean(beanName, new DisposableBeanAdapter(bean, beanName, mbd, getBeanPostProcessorCache().destructionAware, acc));}else {// A bean with a custom scope...Scope scope = this.scopes.get(mbd.getScope());if (scope == null) {throw new IllegalStateException("No Scope registered for scope name '" + mbd.getScope() + "'");}scope.registerDestructionCallback(beanName, new DisposableBeanAdapter(bean, beanName, mbd, getBeanPostProcessorCache().destructionAware, acc));}}}/*** Determine whether the given bean requires destruction on shutdown.* <p>The default implementation checks the DisposableBean interface as well as* a specified destroy method and registered DestructionAwareBeanPostProcessors.* @param bean the bean instance to check* @param mbd the corresponding bean definition* @see org.springframework.beans.factory.DisposableBean* @see AbstractBeanDefinition#getDestroyMethodName()* @see org.springframework.beans.factory.config.DestructionAwareBeanPostProcessor*/protected boolean requiresDestruction(Object bean, RootBeanDefinition mbd) {// 有没有销毁方法，有没有指定销毁方法return (bean.getClass() != NullBean.class && (DisposableBeanAdapter.hasDestroyMethod(bean, mbd) ||(hasDestructionAwareBeanPostProcessors() && DisposableBeanAdapter.hasApplicableProcessors(bean, getBeanPostProcessorCache().destructionAware))));}
}class DisposableBeanAdapter implements DisposableBean, Runnable, Serializable {/*** Check whether the given bean has any kind of destroy method to call.* @param bean the bean instance* @param beanDefinition the corresponding bean definition*/public static boolean hasDestroyMethod(Object bean, RootBeanDefinition beanDefinition) {// 实现接口DisposableBean或者AutoCloseable，有销毁的方法if (bean instanceof DisposableBean || bean instanceof AutoCloseable) {return true;}return inferDestroyMethodIfNecessary(bean, beanDefinition) != null;}/*** If the current value of the given beanDefinition's "destroyMethodName" property is* {@link AbstractBeanDefinition#INFER_METHOD}, then attempt to infer a destroy method.* Candidate methods are currently limited to public, no-arg methods named "close" or* "shutdown" (whether declared locally or inherited). The given BeanDefinition's* "destroyMethodName" is updated to be null if no such method is found, otherwise set* to the name of the inferred method. This constant serves as the default for the* {@code @Bean#destroyMethod} attribute and the value of the constant may also be* used in XML within the {@code <bean destroy-method="">} or {@code* <beans default-destroy-method="">} attributes.* <p>Also processes the {@link java.io.Closeable} and {@link java.lang.AutoCloseable}* interfaces, reflectively calling the "close" method on implementing beans as well.*/@Nullableprivate static String inferDestroyMethodIfNecessary(Object bean, RootBeanDefinition beanDefinition) {String destroyMethodName = beanDefinition.resolvedDestroyMethodName;if (destroyMethodName == null) {destroyMethodName = beanDefinition.getDestroyMethodName(); // INFER_METHOD = "(inferred)"; 特定情况使用类内部的close和shntdown方法if (AbstractBeanDefinition.INFER_METHOD.equals(destroyMethodName) ||(destroyMethodName == null && bean instanceof AutoCloseable)) {// Only perform destroy method inference or Closeable detection// in case of the bean not explicitly implementing DisposableBeandestroyMethodName = null;if (!(bean instanceof DisposableBean)) {try {destroyMethodName = bean.getClass().getMethod(CLOSE_METHOD_NAME).getName();}catch (NoSuchMethodException ex) {try {destroyMethodName = bean.getClass().getMethod(SHUTDOWN_METHOD_NAME).getName();}catch (NoSuchMethodException ex2) {// no candidate destroy method found}}}}beanDefinition.resolvedDestroyMethodName = (destroyMethodName != null ? destroyMethodName : "");}return (StringUtils.hasLength(destroyMethodName) ? destroyMethodName : null);}/*** Check whether the given bean has destruction-aware post-processors applying to it.* @param bean the bean instance* @param postProcessors the post-processor candidates*/public static boolean hasApplicableProcessors(Object bean, List<DestructionAwareBeanPostProcessor> postProcessors) {if (!CollectionUtils.isEmpty(postProcessors)) {for (DestructionAwareBeanPostProcessor processor : postProcessors) {if (processor.requiresDestruction(bean)) {return true;}}}return false;}
}

执行销毁的逻辑：

AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(AppConfig.class);
// 方案一: 注册关闭钩子，进程正常关闭的时候会去调用销毁方法
applicationContext.registerShutdownHook();
// 方案二: 调用容器的close方法
applicationContext.close();/*** Register a shutdown hook {@linkplain Thread#getName() named}* {@code SpringContextShutdownHook} with the JVM runtime, closing this* context on JVM shutdown unless it has already been closed at that time.* <p>Delegates to {@code doClose()} for the actual closing procedure.* @see Runtime#addShutdownHook* @see ConfigurableApplicationContext#SHUTDOWN_HOOK_THREAD_NAME* @see #doClose()*/
@Override
public void registerShutdownHook() {if (this.shutdownHook == null) {// No shutdown hook registered yet.this.shutdownHook = new Thread(SHUTDOWN_HOOK_THREAD_NAME) {@Overridepublic void run() {synchronized (startupShutdownMonitor) {doClose();}}};Runtime.getRuntime().addShutdownHook(this.shutdownHook);}
}/*** Actually performs context closing: publishes a ContextClosedEvent and* destroys the singletons in the bean factory of this application context.* <p>Called by both {@code close()} and a JVM shutdown hook, if any.* @see org.springframework.context.event.ContextClosedEvent* @see #destroyBeans()* @see #close()* @see #registerShutdownHook()*/
@SuppressWarnings("deprecation")
protected void doClose() {// Check whether an actual close attempt is necessary...if (this.active.get() && this.closed.compareAndSet(false, true)) {if (logger.isDebugEnabled()) {logger.debug("Closing " + this);}if (!NativeDetector.inNativeImage()) {LiveBeansView.unregisterApplicationContext(this);}try {// Publish shutdown event.publishEvent(new ContextClosedEvent(this));}catch (Throwable ex) {logger.warn("Exception thrown from ApplicationListener handling ContextClosedEvent", ex);}// Stop all Lifecycle beans, to avoid delays during individual destruction.if (this.lifecycleProcessor != null) {try {this.lifecycleProcessor.onClose();}catch (Throwable ex) {logger.warn("Exception thrown from LifecycleProcessor on context close", ex);}}// Destroy all cached singletons in the context's BeanFactory.destroyBeans();// Close the state of this context itself.closeBeanFactory();// Let subclasses do some final clean-up if they wish...onClose();// Reset local application listeners to pre-refresh state.if (this.earlyApplicationListeners != null) {this.applicationListeners.clear();this.applicationListeners.addAll(this.earlyApplicationListeners);}// Switch to inactive.this.active.set(false);}
}

定义销毁逻辑：

// 方案一: 注册钩子或关闭容器执行销毁逻辑
@Component
public class UserService implements DisposableBean
{@Overridepublic void destroy() throws Exception {System.out.println(222);}
}// 方案二: 注册钩子或关闭容器执行销毁逻辑
@Component
public class UserService implements AutoCloseable
{@Overridepublic void close() throws Exception {System.out.println(333);}
}// 方案三: 注册钩子或关闭容器执行销毁逻辑
@Component
public class GaxBeanPostProcessor implements MergedBeanDefinitionPostProcessor
{@Overridepublic void postProcessMergedBeanDefinition(RootBeanDefinition beanDefinition, Class<?> beanType, String beanName){if ("userService".equals(beanName)){// 指定销毁方法的名字，固定字符串beanDefinition.setDestroyMethodName("(inferred)");}}
}@Component
public class UserService
{// 有close方法就执行close销毁public void close(){System.out.println(444);}// 没有close方法，再执行shutdown销毁public void shutdown(){System.out.println(555);}
}