spring 事件模式 源码导读

一,jdk 事件对象基类package java.util;import java.io.Serializable;public class EventObject  implements Serializable{  protected transient Object source;  public Object getSource()  {    return this.source;  }  public EventObject(Object paramObject)  {    if (paramObject == null)      throw new IllegalArgumentException("null source");    this.source = paramObject;  }  public String toString()  {    return getClass().getName() + "[source=" + this.source + "]";  }}2，spring事件基类public abstract class ApplicationEvent extends EventObject {/** use serialVersionUID from Spring 1.2 for interoperability */private static final long serialVersionUID = 7099057708183571937L;/** System time when the event happened */private final long timestamp;/** * Create a new ApplicationEvent. * @param source the component that published the event (never <code>null</code>) */public ApplicationEvent(Object source) {super(source);this.timestamp = System.currentTimeMillis();}/** * Return the system time in milliseconds when the event happened. */public final long getTimestamp() {return this.timestamp;}}3，ApplicationContextEvent基类public abstract class ApplicationContextEvent extends ApplicationEvent {/** * Create a new ContextStartedEvent. * @param source the <code>ApplicationContext</code> that the event is raised for * (must not be <code>null</code>) */public ApplicationContextEvent(ApplicationContext source) {super(source);}/** * Get the <code>ApplicationContext</code> that the event was raised for. */public final ApplicationContext getApplicationContext() {return (ApplicationContext) getSource();}}4，容器关闭事件public class ContextClosedEvent extends ApplicationContextEvent {/** * Creates a new ContextClosedEvent. * @param source the <code>ApplicationContext</code> that has been closed * (must not be <code>null</code>) */public ContextClosedEvent(ApplicationContext source) {super(source);}}5，AbstractApplicationContext中fireclose事件public void publishEvent(ApplicationEvent event) {Assert.notNull(event, "Event must not be null");if (logger.isTraceEnabled()) {logger.trace("Publishing event in " + getDisplayName() + ": " + event);}getApplicationEventMulticaster().multicastEvent(event);if (this.parent != null) {this.parent.publishEvent(event);}}6，事件处理监听器控制器(SimpleApplicationEventMulticaster)@SuppressWarnings("unchecked")public void multicastEvent(final ApplicationEvent event) {for (final ApplicationListener listener : getApplicationListeners(event)) {Executor executor = getTaskExecutor();if (executor != null) {executor.execute(new Runnable() {@SuppressWarnings("unchecked")public void run() {listener.onApplicationEvent(event);}});}else {listener.onApplicationEvent(event);}}}7，AbstractApplicationEventMulticaster获取注册close事件的监听器protected Collection<applicationlistener> getApplicationListeners(ApplicationEvent event) {Class<? extends ApplicationEvent> eventType = event.getClass();Class sourceType = event.getSource().getClass();ListenerCacheKey cacheKey = new ListenerCacheKey(eventType, sourceType);ListenerRetriever retriever = this.retrieverCache.get(cacheKey);if (retriever != null) {return retriever.getApplicationListeners();}else {retriever = new ListenerRetriever(true);LinkedList<applicationlistener> allListeners = new LinkedList<applicationlistener>();synchronized (this.defaultRetriever) {for (ApplicationListener listener : this.defaultRetriever.applicationListeners) {if (supportsEvent(listener, eventType, sourceType)) {retriever.applicationListeners.add(listener);allListeners.add(listener);}}if (!this.defaultRetriever.applicationListenerBeans.isEmpty()) {BeanFactory beanFactory = getBeanFactory();for (String listenerBeanName : this.defaultRetriever.applicationListenerBeans) {ApplicationListener listener = beanFactory.getBean(listenerBeanName, ApplicationListener.class);if (!allListeners.contains(listener) && supportsEvent(listener, eventType, sourceType)) {retriever.applicationListenerBeans.add(listenerBeanName);allListeners.add(listener);}}}OrderComparator.sort(allListeners);this.retrieverCache.put(cacheKey, retriever);}return allListeners;}}二,1，监听器基类public  interface EventListener{}2，spring监听器基类public interface ApplicationListener<e extends="" applicationevent=""> extends EventListener {/** * Handle an application event. * @param event the event to respond to */void onApplicationEvent(E event);}3，AbstractApplicationContext添加监听public void addApplicationListener(ApplicationListener<?> listener) {if (this.applicationEventMulticaster != null) {this.applicationEventMulticaster.addApplicationListener(listener);}else {this.applicationListeners.add(listener);}}4，添加listenner到AbstractApplicationEventMulticasterpublic void addApplicationListener(ApplicationListener listener) {synchronized (this.defaultRetriever) {this.defaultRetriever.applicationListeners.add(listener);this.retrieverCache.clear();}}5，监听处理类注册入口AbstractApplicationContextpublic Object postProcessAfterInitialization(Object bean, String beanName) {if (bean instanceof ApplicationListener) {// potentially not detected as a listener by getBeanNamesForType retrievalBoolean flag = this.singletonNames.get(beanName);if (Boolean.TRUE.equals(flag)) {// singleton bean (top-level or inner): register on the flyaddApplicationListener((ApplicationListener<?>) bean);}else if (flag == null) {if (logger.isWarnEnabled() && !containsBean(beanName)) {// inner bean with other scope - can't reliably process eventslogger.warn("Inner bean '" + beanName + "' implements ApplicationListener interface " +"but is not reachable for event multicasting by its containing ApplicationContext " +"because it does not have singleton scope. Only top-level listener beans are allowed " +"to be of non-singleton scope.");}this.singletonNames.put(beanName, Boolean.FALSE);}}return bean;}</e></applicationlistener></applicationlistener></applicationlistener>