(1). 概述
前面,通过源码剖析,SI会委托给ServiceActivatorParser解析service-activator标签,最终会转换成业务模型:ServiceActivatorFactoryBean,在这一小节,主要是剖析:ServiceActivatorFactoryBean.
(2). 先看下ServiceActivatorFactoryBean类的关系图
org.springframework.integration.config.AbstractSimpleMessageHandlerFactoryBean
org.springframework.integration.config.AbstractStandardMessageHandlerFactoryBean
org.springframework.integration.config.ServiceActivatorFactoryBean
(3). AbstractSimpleMessageHandlerFactoryBean
public abstract class AbstractSimpleMessageHandlerFactoryBean<H extends MessageHandler>
implements
// **********************************************************************************
// FactoryBean固名思义,就是产生Bean的工厂,所以,重点要关注这个类的:getObject方法.
// **********************************************************************************
FactoryBean<MessageHandler>,
ApplicationContextAware,
BeanFactoryAware,
BeanNameAware,
ApplicationEventPublisherAware {
}
(4). AbstractSimpleMessageHandlerFactoryBean
public abstract class AbstractSimpleMessageHandlerFactoryBean<H extends MessageHandler>
implements FactoryBean<MessageHandler>, ApplicationContextAware, BeanFactoryAware, BeanNameAware,
ApplicationEventPublisherAware {
private volatile H handler;
@Override
public H getObject() throws Exception {
if (this.handler == null) {
// *******************************************************************************************
// 1. 委托给了:createHandlerInternal
// *******************************************************************************************
this.handler = this.createHandlerInternal();
Assert.notNull(this.handler, "failed to create MessageHandler");
}
return this.handler;
} // end getObject
protected final H createHandlerInternal() {
synchronized (this.initializationMonitor) {
if (this.initialized) {
// There was a problem when this method was called already
return null;
}
// *******************************************************************************************
// 2. 委托给了子类(AbstractStandardMessageHandlerFactoryBean)的createHandler
// *******************************************************************************************
this.handler = createHandler();
// 余下的信息,都是配置Spring的一些钩子对象(ApplicationContextAware/BeanNameAware/ApplicationEventPublisherAware/MessageProducer/IntegrationObjectSupport/)
if (this.handler instanceof ApplicationContextAware && this.applicationContext != null) {
((ApplicationContextAware) this.handler).setApplicationContext(this.applicationContext);
}
if (this.handler instanceof BeanFactoryAware && getBeanFactory() != null) {
((BeanFactoryAware) this.handler).setBeanFactory(getBeanFactory());
}
if (this.handler instanceof BeanNameAware && this.beanName != null) {
((BeanNameAware) this.handler).setBeanName(this.beanName);
}
if (this.handler instanceof ApplicationEventPublisherAware && this.applicationEventPublisher != null) {
((ApplicationEventPublisherAware) this.handler)
.setApplicationEventPublisher(this.applicationEventPublisher);
}
<<<<<<< HEAD
// ********************************************************************************
// 设置setOutputChannel
// ********************************************************************************
=======
// ***************************************************************************
// 设置:outputChannel
// ***************************************************************************
>>>>>>> b6ab82f117acbb232196bc1220b46d22870d945e
if (this.handler instanceof MessageProducer && this.outputChannel != null) {
((MessageProducer) this.handler).setOutputChannel(this.outputChannel);
}
Object actualHandler = extractTarget(this.handler);
if (actualHandler == null) {
actualHandler = this.handler;
}
if (actualHandler instanceof IntegrationObjectSupport) {
if (this.componentName != null) {
((IntegrationObjectSupport) actualHandler).setComponentName(this.componentName);
}
if (this.channelResolver != null) {
((IntegrationObjectSupport) actualHandler).setChannelResolver(this.channelResolver);
}
}
// 好像还有责任链的功能
if (!CollectionUtils.isEmpty(this.adviceChain)) {
if (actualHandler instanceof AbstractReplyProducingMessageHandler) {
((AbstractReplyProducingMessageHandler) actualHandler).setAdviceChain(this.adviceChain);
}
else if (this.logger.isDebugEnabled()) {
String name = this.componentName;
if (name == null && actualHandler instanceof NamedComponent) {
name = ((NamedComponent) actualHandler).getComponentName();
}
this.logger.debug("adviceChain can only be set on an AbstractReplyProducingMessageHandler"
+ (name == null ? "" : (", " + name)) + ".");
}
}
if (this.async != null) {
if (actualHandler instanceof AbstractReplyProducingMessageHandler) {
((AbstractReplyProducingMessageHandler) actualHandler)
.setAsync(this.async);
}
}
if (this.handler instanceof Orderable && this.order != null) {
((Orderable) this.handler).setOrder(this.order);
}
this.initialized = true;
}
if (this.handler instanceof InitializingBean) {
try {
// ********************************************************************************
// 手动调用:afterPropertiesSet
// ********************************************************************************
((InitializingBean) this.handler).afterPropertiesSet();
}
catch (Exception e) {
throw new BeanInitializationException("failed to initialize MessageHandler", e);
}
}
return this.handler;
} // end createHandlerInternal
}
(5). AbstractStandardMessageHandlerFactoryBean
public abstract class AbstractStandardMessageHandlerFactoryBean
extends AbstractSimpleMessageHandlerFactoryBean<MessageHandler> {
private static final ExpressionParser expressionParser = new SpelExpressionParser(new SpelParserConfiguration(true,
true));
private static final Set<MessageHandler> referencedReplyProducers = new HashSet<MessageHandler>();
// *******************************************************************************************
// 目标对象(org.springframework.integration.samples.helloworld.HelloService)
// *******************************************************************************************
private volatile Object targetObject;
// *******************************************************************************************
// 目标方法(sayHello)
// *******************************************************************************************
private volatile String targetMethodName;
private volatile Expression expression;
// *******************************************************************************************
// 创建:MessageHandler
// *******************************************************************************************
protected MessageHandler createHandler() {
MessageHandler handler;
// 1. 验证targetMethodName是否不为字符串
if (this.targetObject == null) {
Assert.isTrue(!StringUtils.hasText(this.targetMethodName), "The target method is only allowed when a target object (ref or inner bean) is also provided.");
}
if (this.targetObject != null) { // 2. 针对targetObject包装成:MessageHandler
Assert.state(this.expression == null, "The 'targetObject' and 'expression' properties are mutually exclusive.");
// 3. 判断targetObject是否为:AbstractMessageProducingHandler,我这里为null
AbstractMessageProducingHandler actualHandler = this.extractTypeIfPossible(this.targetObject, AbstractMessageProducingHandler.class);
// 4. targetIsDirectReplyProducingHandler = false
boolean targetIsDirectReplyProducingHandler = actualHandler != null && this.canBeUsedDirect(actualHandler) && this.methodIsHandleMessageOrEmpty(this.targetMethodName);
// 5. 判断targetObject(HelloService) 是否为: MessageProcessor
if (this.targetObject instanceof MessageProcessor<?>) { // false
handler = this.createMessageProcessingHandler((MessageProcessor<?>) this.targetObject);
} else if (targetIsDirectReplyProducingHandler) { // false
if (logger.isDebugEnabled()) {
logger.debug("Wiring handler (" + this.targetObject + ") directly into endpoint");
}
this.checkReuse(actualHandler);
this.postProcessReplyProducer(actualHandler);
handler = (MessageHandler) this.targetObject;
} else {
// ***********************************************************************************
// 6. 委托给子类(ServiceActivatorFactoryBean)创建:MessageHandler
// ***********************************************************************************
handler = this.createMethodInvokingHandler(this.targetObject, this.targetMethodName);
}
} else if (this.expression != null) {
// 针对expression包装成:MessageHandler
handler = this.createExpressionEvaluatingHandler(this.expression);
} else {
// 既没指定:targetObject和expression,则,创建默认的:MessageHandler
handler = this.createDefaultHandler();
}
return handler;
} // end createHandler
}
(6). ServiceActivatorFactoryBean
public class ServiceActivatorFactoryBean extends AbstractStandardMessageHandlerFactoryBean {
// *******************************************************************************************
//
// *******************************************************************************************
protected MessageHandler createMethodInvokingHandler(Object targetObject, String targetMethodName) {
MessageHandler handler = null;
// 1. 如果targetObject为MessageHandler并且,targetMethodName为:handleMessage的话,则,返回:MessageHandler
handler = createDirectHandlerIfPossible(targetObject, targetMethodName);
if (handler == null) { // true
handler = configureHandler(
// 判断:targetMethodName(sayHello)是否为字符串.
StringUtils.hasText(targetMethodName)
// ********************************************************************************************
// 2. 创建:ServiceActivatingHandler对象,包裹着:targetObject与targetMethodName
// ********************************************************************************************
? new ServiceActivatingHandler(targetObject, targetMethodName)
//
: new ServiceActivatingHandler(targetObject));
}
return handler;
}// end createMethodInvokingHandler
}
(7). 总结
ServiceActivatorFactoryBean的工厂方法(getObject),最终是创建了:ServiceActivatingHandler(属于MessageHandler的实现)对象包裹我们的业务对象(HelloService)和方法(sayHello).
