本文主要分析spring事务代理的源码，跟踪代码，了解事务代理的生命周期
1.学习资料和书籍
2.代理的生成(原理)
3.代理的使用-使用中遇到的常见问题
涉及的源码类：
org.springframework.aop.config.AopNamespaceUtils
org.springframework.aop.config.AopConfigUtils
org.springframework.aop.framework.autoproxy.InfrastructureAdvisorAutoProxyCreator
org.springframework.aop.framework.ProxyConfig
org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator
org.springframework.aop.support.AopUtils
org.springframework.aop.framework.ProxyFactory
org.springframework.transaction.config.TxNamespaceHandler
org.springframework.transaction.config.AnnotationDrivenBeanDefinitionParser
org.springframework.transaction.annotation.AnnotationTransactionAttributeSource
org.springframework.transaction.interceptor.TransactionInterceptor
org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction
org.springframework.transaction.interceptor.BeanFactoryTransactionAttributeSourceAdvisor
1.学习资料和书籍
grepcode源码及相关博客
2.代理的生成
涉及事务代理的spring元素及特性：
xml配置:
[size=large]2.1 <tx:annotation-driven transaction-manager=”transactionManager” />[/size]
当XML中存在“<tx:annotation-driven/>”时，命名空间为tx。从相关的jar包(如spring-tx.jar)中可查看标签处理类。从配置文件spring.handlers中查找到的NamespaceHandler为org.springframework.transaction.config.TxNamespaceHandler
。由TxNamespaceHandler负责具体的解析tx命名空间
部分代码如下：
static final String TRANSACTION_MANAGER_ATTRIBUTE = "transaction-manager";
static final String DEFAULT_TRANSACTION_MANAGER_BEAN_NAME = "transactionManager";
public void init() {
registerBeanDefinitionParser("advice", new TxAdviceBeanDefinitionParser());
registerBeanDefinitionParser("annotation-driven", new AnnotationDrivenBeanDefinitionParser());
registerBeanDefinitionParser("jta-transaction-manager", new JtaTransactionManagerBeanDefinitionParser());
}解析annotation-driven的类为org.springframework.transaction.config.AnnotationDrivenBeanDefinitionParser，源码可查看如下：
[url]http://grepcode.com/file/repository.springsource.com/org.springframework/org.springframework.transaction/3.2.2/org/springframework/transaction/config/AnnotationDrivenBeanDefinitionParser.java?av=f[/url]
部分源码如下：
public static final String TRANSACTION_ADVISOR_BEAN_NAME =
"org.springframework.transaction.config.internalTransactionAdvisor";
AnnotationDrivenBeanDefinitionParser#parse
public BeanDefinition parse(Element element, ParserContext parserContext) {
String mode = element.getAttribute("mode");
if ("aspectj".equals(mode)) {
// mode="aspectj"
registerTransactionAspect(element, parserContext);
}
else {
// mode="proxy"
AopAutoProxyConfigurer.configureAutoProxyCreator(element, parserContext);
}
return null;
}查看spring-tx-3.0.xsd可知，mode=proxy。内部类AopAutoProxyConfigurer为实际代理模式下引入aop框架，部分代码如下：
[size=large]AopAutoProxyConfigurer.configureAutoProxyCreator方法分析：事务定义的入口[/size]
AnnotationDrivenBeanDefinitionParser.AopAutoProxyConfigurer#configureAutoProxyCreator
public static void configureAutoProxyCreator(Element element, ParserContext parserContext) {
AopNamespaceUtils.registerAutoProxyCreatorIfNecessary(parserContext, element);
String txAdvisorBeanName = TransactionManagementConfigUtils.TRANSACTION_ADVISOR_BEAN_NAME;
if (!parserContext.getRegistry().containsBeanDefinition(txAdvisorBeanName)) {
Object eleSource = parserContext.extractSource(element);
// Create the TransactionAttributeSource definition.
RootBeanDefinition sourceDef = new RootBeanDefinition(AnnotationTransactionAttributeSource.class);
sourceDef.setSource(eleSource);
sourceDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
String sourceName = parserContext.getReaderContext().registerWithGeneratedName(sourceDef);
// Create the TransactionInterceptor definition.
RootBeanDefinition interceptorDef = new RootBeanDefinition(TransactionInterceptor.class);
interceptorDef.setSource(eleSource);
interceptorDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
registerTransactionManager(element, interceptorDef);
interceptorDef.getPropertyValues().add("transactionAttributeSource", new RuntimeBeanReference(sourceName));
String interceptorName = parserContext.getReaderContext().registerWithGeneratedName(interceptorDef);
// Create the TransactionAttributeSourceAdvisor definition.
RootBeanDefinition advisorDef = new RootBeanDefinition(BeanFactoryTransactionAttributeSourceAdvisor.class);
advisorDef.setSource(eleSource);
advisorDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
advisorDef.getPropertyValues().add("transactionAttributeSource", new RuntimeBeanReference(sourceName));
advisorDef.getPropertyValues().add("adviceBeanName", interceptorName);
if (element.hasAttribute("order")) {
advisorDef.getPropertyValues().add("order", element.getAttribute("order"));
}
parserContext.getRegistry().registerBeanDefinition(txAdvisorBeanName, advisorDef);
CompositeComponentDefinition compositeDef = new CompositeComponentDefinition(element.getTagName(), eleSource);
compositeDef.addNestedComponent(new BeanComponentDefinition(sourceDef, sourceName));
compositeDef.addNestedComponent(new BeanComponentDefinition(interceptorDef, interceptorName));
compositeDef.addNestedComponent(new BeanComponentDefinition(advisorDef, txAdvisorBeanName));
parserContext.registerComponent(compositeDef);
}
}[b][size=medium]创建InfrastructureAdvisorAutoProxyCreator的beanDefinition[/size][/b]
a.定义后置处理器(InfrastructureAdvisorAutoProxyCreator)-[b][color=green]根据配置信息，定义生成代理的入口[/color][/b]
AopNamespaceUtils.registerAutoProxyCreatorIfNecessary(parserContext, element); 创建事务代理的后置处理器InfrastructureAdvisorAutoProxyCreator
[img]http://dl2.iteye.com/upload/attachment/0123/9164/e1b6144b-fc73-372a-913d-602ddb64e882.png[/img]
[img]http://dl2.iteye.com/upload/attachment/0123/8459/9742b9ad-1466-3979-9c4e-5d6d6a1826d5.png[/img]
———————-代码直译start———————-
第一行：创建名为AUTO_PROXY_CREATOR_BEAN_NAME=org.springframework.aop.config.internalAutoProxyCreator的后置处理器InfrastructureAdvisorAutoProxyCreator([color=red]实现了BeanPostProcessor[/color])，且名为AUTO_PROXY_CREATOR_BEAN_NAME的后置处理器只有一个
尚未注册，第三行注册
第二行：给AUTO_PROXY_CREATOR_BEAN_NAME设置属性
解析
PROXY_TARGET_CLASS_ATTRIBUTE = “proxy-target-class”
EXPOSE_PROXY_ATTRIBUTE = “expose-proxy”
设置后置处理器相关属性值
proxyTargetClass=true或
exposeProxy=true
（这2个属性在org.springframework.aop.framework.ProxyConfig中）
第三行：注册到容器
———————-代码直译end———————-
InfrastructureAdvisorAutoProxyCreator源码：
[url]http://grepcode.com/file/repository.springsource.com/org.springframework/org.springframework.aop/3.2.2/org/springframework/aop/framework/autoproxy/InfrastructureAdvisorAutoProxyCreator.java#InfrastructureAdvisorAutoProxyCreator[/url]
AbstractAdvisorAutoProxyCreator源码：
[url]http://grepcode.com/file/repository.springsource.com/org.springframework/org.springframework.aop/3.2.2/org/springframework/aop/framework/autoproxy/AbstractAdvisorAutoProxyCreator.java#AbstractAdvisorAutoProxyCreator[/url]
AbstractAutoProxyCreator源码：
[url]http://grepcode.com/file/repository.springsource.com/org.springframework/org.springframework.aop/3.2.2/org/springframework/aop/framework/autoproxy/AbstractAutoProxyCreator.java#AbstractAutoProxyCreator[/url]
[b][size=medium]执行InfrastructureAdvisorAutoProxyCreator[/size][/b]
a.1 AbstractApplicationContext.refresh-[b][color=green]执行生成代理的入口,调用以上定义的入口生成代理[/color][/b]
单一职责原则：[color=red]AbstractAutoProxyCreator[/color].postProcessAfterInitialization(Object bean, String beanName)(有图可知AbstractAutoProxyCreator为InfrastructureAdvisorAutoProxyCreator祖先类，祖先类中定义了模板方法),继续调用wrapIfNecessary方法
[color=red]在实例化bean后，调用初始化方法后执行[/color]
该方法中：
[color=red](1)获取拦截器主要在后置处理器中完成 (2)创建代理委托给ProxyFactory完成[/color]
(1) 首先查找所有符合条件的Advisor类型的类(抽象方法：getAdvicesAndAdvisorsForBean)。
该任务委托由AbstractAdvisorAutoProxyCreator.getAdvicesAndAdvisorsForBean完成(有图可知[color=red]AbstractAdvisorAutoProxyCreator[/color]为AbstractAutoProxyCreator的子类，InfrastructureAdvisorAutoProxyCreator的父类),继续调用findEligibleAdvisors，在该方法中，
(1.1)首先调用findCandidateAdvisors()方法，查找所有advisor类型的类
[size=medium][color=red]abstractAutoProxyCreator[/color].postProcessAfterInitialization->[color=red]abstractAutoProxyCreator[/color].wrapIfNecessary->[color=red]abstractAdvisorAutoProxyCreator[/color].getAdvicesAndAdvisorsForBean->[color=red]abstractAdvisorAutoProxyCreator[/color].findEligibleAdvisors->[color=red]abstractAdvisorAutoProxyCreator[/color].findCandidateAdvisors->[color=red]advisorRetrievalHelper[/color].findAdvisorBeans()->[color=red]BeanFactoryUtils[/color].beanNamesForTypeIncludingAncestors->[color=red]beanFactory[/color].getBean(name, Advisor.class)[/size]
[size=medium][color=red]advisorRetrievalHelper[/color].findAdvisorBeans()[/size]方法中，循环advisorNames
BeanFactoryAdvisorRetrievalHelper源码：
[url]http://grepcode.com/file/repository.springsource.com/org.springframework/org.springframework.aop/3.2.2/org/springframework/aop/framework/autoproxy/BeanFactoryAdvisorRetrievalHelper.java#BeanFactoryAdvisorRetrievalHelper.findAdvisorBeans%28%29[/url]
(1.2)其次调用findAdvisorsThatCanApply()方法，查找所有上一步中符合条件的advisor。
[size=medium][color=red]abstractAutoProxyCreator[/color].postProcessAfterInitialization->[color=red]abstractAutoProxyCreator[/color].wrapIfNecessary->[color=red]abstractAdvisorAutoProxyCreator[/color].getAdvicesAndAdvisorsForBean->[color=red]abstractAdvisorAutoProxyCreator[/color].findEligibleAdvisors->[color=red]abstractAdvisorAutoProxyCreator[/color].findAdvisorsThatCanApply->[color=red]AopUtils[/color].findAdvisorsThatCanApply->[color=red]advisor[/color].getPointCut->[color=red]pointcut[/color].matches->[color=red]tas[/color].getTransactionAttribute 最终返回符合条件的advisor[/size]
[size=medium][color=red]AopUtils[/color].findAdvisorsThatCanApply(candidateAdvisors, beanClass)[/size]方法,
该方法中循环candidateAdvisors，调用canApply(Advisor advisor, Class<?> targetClass, boolean hasIntroductions),根据advisor获取pointcut,继续调用canApply(Pointcut pc, Class<?> targetClass, boolean hasIntroductions)，通过pc.getMethodMatcher（）获取methodMatcher，这个类是真正判断该类或方法适合符合事物,即该类或方法是否有@Transaction注释
如果bean不适合该advisor,即没有@Transaction注释，则返回false,并将该bean放入this.advisedBeans.put(cacheKey, Boolean.FALSE),并最终返回bean
否则创建代理,(1)最终过滤符合条件的拦截器specificInterceptors
对于BeanFactoryTransactionAttributeSourceAdvisor持有对象TransactionAttributeSourcePointcut,具体分析见(d)
(2) 创建代理AopProxy,并通过aopProxy.getProxy返回最终代理bean。
[img]http://dl2.iteye.com/upload/attachment/0123/9283/a36fc802-1a2e-3c78-8f1a-ba040c31c17c.png[/img]
[size=medium][color=red]abstractAutoProxyCreator[/color].postProcessAfterInitialization->[color=red]abstractAutoProxyCreator[/color].wrapIfNecessary->[color=red]abstractAutoProxyCreator[/color].createProxy->[color=red]proxyFactory[/color].getProxy->[color=red]proxyFactory[/color].createAopProxy().getProxy->[color=red]jdkDynamicAopProxy[/color].getProxy或cglibProxy.getProxy->[color=red]java.lang.reflect.Proxy[/color].newProxyInstance(classLoader, proxiedInterfaces, this): 最终返回proxy[/size]
this即为aopProxy（jdkDynamicAopProxy或cglibProxy）其实现了InvocationHandler接口
[color=red]proxy何时调用？[/color]
用户业务对象的代理调用时，最终调用invocationHandler.invoke方法
通过jdkDynamicAopProxy源码了解其invoke方法
[url]http://grepcode.com/file/repository.springsource.com/org.springframework/org.springframework.aop/3.2.2/org/springframework/aop/framework/JdkDynamicAopProxy.java#JdkDynamicAopProxy[/url]
[size=medium][color=red]abstractAutoProxyCreator[/color].createProxy(bean.getClass(), beanName, specificInterceptors, new SingletonTargetSource(bean))[/size]，在该方法中创建[color=red]ProxyFactory[/color],并设置属性
ProxyFactory源码：
[url]http://grepcode.com/file/repository.springsource.com/org.springframework/org.springframework.aop/3.2.2/org/springframework/aop/framework/ProxyFactory.java#ProxyFactory.getProxy%28java.lang.ClassLoader%29[/url]
ProxyFactory proxyFactory = new ProxyFactory();
// Copy our properties (proxyTargetClass etc) inherited from ProxyConfig.
proxyFactory.copyFrom(this);
if (!shouldProxyTargetClass(beanClass, beanName)) {
// Must allow for introductions; can't just set interfaces to
// the target's interfaces only.
Class<?>[] targetInterfaces = ClassUtils.getAllInterfacesForClass(beanClass, this.proxyClassLoader);
for (Class<?> targetInterface : targetInterfaces) {
proxyFactory.addInterface(targetInterface);
}
}
Advisor[] advisors = buildAdvisors(beanName, specificInterceptors);
for (Advisor advisor : advisors) {
proxyFactory.addAdvisor(advisor);
}
proxyFactory.setTargetSource(targetSource);
customizeProxyFactory(proxyFactory);
proxyFactory.setFrozen(this.freezeProxy);
if (advisorsPreFiltered()) {
proxyFactory.setPreFiltered(true);
}
return proxyFactory.getProxy(this.proxyClassLoader);最后一句proxyFactory.getProxy(this.proxyClassLoader);此处创建代理。
public Object getProxy(ClassLoader classLoader) {
return createAopProxy().getProxy(classLoader);
}该方法中createAopProxy()返回AopProxy如下：
[color=red]proxyCreatorSupport[/color].createAopProxy()创建代理
protected final synchronized AopProxy createAopProxy() {
if (!this.active) {
activate();
}
return getAopProxyFactory().createAopProxy(this);
}getAopProxyFactory()方法中获取ProxyCreatorSupport的内置对象aopProxyFactory（[color=red]new DefaultAopProxyFactory()[/color]）。
DefaultAopProxyFactory源码：
[url]http://grepcode.com/file/repository.springsource.com/org.springframework/org.springframework.aop/3.2.2/org/springframework/aop/framework/DefaultAopProxyFactory.java#DefaultAopProxyFactory[/url]
getAopProxyFactory().createAopProxy(this)该方法返回AopProxy
public AopProxy createAopProxy(AdvisedSupport config) throws AopConfigException {
if (config.isOptimize() || config.isProxyTargetClass() || hasNoUserSuppliedProxyInterfaces(config)) {
Class targetClass = config.getTargetClass();
if (targetClass == null) {
throw new AopConfigException("TargetSource cannot determine target class: " +
"Either an interface or a target is required for proxy creation.");
}
if (targetClass.isInterface()) {
return new JdkDynamicAopProxy(config);
}
return CglibProxyFactory.createCglibProxy(config);
}
else {
return new JdkDynamicAopProxy(config);
}
}[img]http://dl2.iteye.com/upload/attachment/0123/9292/22447235-2511-3553-ab46-c039b48652f9.png[/img]
createAopProxy().getProxy(classLoader);以jdk生成代理为例
jdkDynamicAopProxy.getProxy(classLoader)
public Object getProxy(ClassLoader classLoader) {
if (logger.isDebugEnabled()) {
logger.debug("Creating JDK dynamic proxy: target source is " + this.advised.getTargetSource());
}
Class[] proxiedInterfaces = AopProxyUtils.completeProxiedInterfaces(this.advised);
findDefinedEqualsAndHashCodeMethods(proxiedInterfaces);
return Proxy.newProxyInstance(classLoader, proxiedInterfaces, this);
}最终返回代理对象
JdkDynamicAopProxy源码：
[url]http://grepcode.com/file/repository.springsource.com/org.springframework/org.springframework.aop/3.2.2/org/springframework/aop/framework/JdkDynamicAopProxy.java#JdkDynamicAopProxy[/url]
[color=red]此后置处理器处理@Transaction注释的bean,创建aopProxy。其他advisor如何处理，事务代理的外面再加一层代理?[/color]
尝试解释：
该后置处理器可以处理多个advisor(包括事务advisor,即BeanFactoryTransactionAttributeSourceAdvisor）
[color=red]自定义advisor，实现相应接口，看否是可以识别?[/color]
[color=red]自定义beanpostprocess,在此前代理上创建代理或者覆盖原先代理对象?[/color]
ProxyCreatorSupport源码：
[url]http://grepcode.com/file/repository.springsource.com/org.springframework/org.springframework.aop/3.2.2/org/springframework/aop/framework/ProxyCreatorSupport.java#ProxyCreatorSupport.createAopProxy%28%29[/url]
[size=large]断点2[/size]
[b][size=medium]创建AnnotationTransactionAttributeSource的beanDefinition[/size][/b]
b.定义AnnotationTransactionAttributeSource-[b][color=green]事务属性,每个业务类或方法可能不同,大部分是一样的[/color][/b]
// Create the TransactionAttributeSource definition.
RootBeanDefinition sourceDef = new RootBeanDefinition(AnnotationTransactionAttributeSource.class);
sourceDef.setSource(eleSource);
sourceDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
String sourceName = parserContext.getReaderContext().registerWithGeneratedName(sourceDef);
创建[color=red]AnnotationTransactionAttribute[/color]Source定义(事务属性来源于注解@Transactional)
单一职责原则：getTransactionAttribute(Method method, Class<?> targetClass)
判断方法或类是否有@Transactional注释,并解析返回TransactionAttribute或null。其内部调用SpringTransactionAnnotationParser来解析是否有@Transactional注解
AnnotationTransactionAttributeSource源码见：
[url]http://grepcode.com/file/repository.springsource.com/org.springframework/org.springframework.transaction/3.2.2/org/springframework/transaction/annotation/AnnotationTransactionAttributeSource.java?av=f[/url]
[color=red]在哪[/color]调用其getTransactionAttribute(Method method, Class<?> targetClass)方法，以获取事务属性?
(1) 在后置处理器，avvisor->pointcut.matches->getTransactionAttribute,用于判断advisor适合适合此bean
(2) 在TransactionInterceptor的invoke方法中调用，更确切的说是在TransactionAspectSupport的invokeWithinTransaction方法中。用于事务定义TransactionInfo
[color=red]用于判断该方法或类是否可开启事务。[/color]
还有其他的事务属性来源,应用于不同的事务配置方式如：NameMatchTransactionAttributeSource
[b][size=medium]创建TransactionInterceptor的beanDefinition[/size][/b]
c.定义TransactionInterceptor-[b][color=green]事务拦截器,执行事务开始，提交，回滚等操作[/color][/b]
[img]http://dl2.iteye.com/upload/attachment/0123/9311/ebb15fcb-47cb-3588-b411-fbfd0956cdfb.png[/img]
// Create the TransactionInterceptor definition.
RootBeanDefinition interceptorDef = new RootBeanDefinition(TransactionInterceptor.class);
interceptorDef.setSource(eleSource);
interceptorDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
registerTransactionManager(element, interceptorDef);
interceptorDef.getPropertyValues().add("transactionAttributeSource", new RuntimeBeanReference(sourceName));
String interceptorName = parserContext.getReaderContext().registerWithGeneratedName(interceptorDef);
创建TransactionInterceptor定义
单一职责原则：invoke(final MethodInvocation invocation)
invoke中调用TransactionAspectSupport的invokeWithinTransaction(Method method, Class targetClass, final InvocationCallback invocation)方法,执行真正的拦截逻辑。在该方法中会调用transactionAttributeSource判断类或方法是否可开启事务，调用transactionManager执行拦截逻辑，即开启提交事务等。
registerTransactionManager(element, interceptorDef);
这行代码，主要是设置TransactionAspectSupport的transactionManager(注册事务管理器)。调用invoke时，设置到生成的TransactionInfo中并管理事务状态。
TransactionInterceptor(拦截器)本身不保存数据，只是起到传递的作用,把真正的处理过程交给TransactionAspectSupport 去完成
[color=red]在哪调用TransactionInterceptor.invoke(final MethodInvocation invocation)?[/color]
在(a)处后置处理器中，生成代理(jdk或cglib代理),invoke方法中调用
transactionInterceptor是advice，是否包装成advisor何时包装?
创建代理时(a(2))封装成advisor:
abstractAutoProxyCreator.buildAdvisors->advisorAdapterRegistry.wrap
调用代理方法时，执行的是methodInterceptor，advisor何时拆解成methodInterceptor?
执行代理方法invoke时，通过advised.getInterceptorsAndDynamicInterceptionAdvice获取methodInterceptor,其中会调用advisorAdapterRegistry.getInterceptors(advisor);
TransactionAspectSupport源码可见：
[url]http://grepcode.com/file/repository.springsource.com/org.springframework/org.springframework.transaction/3.2.2/org/springframework/transaction/interceptor/TransactionAspectSupport.java#TransactionAspectSupport.TransactionInfo.bindToThread%28%29[/url]
joinpointIdentification
TransactionInterceptor源码见：
[url]http://grepcode.com/file/repository.springsource.com/org.springframework/org.springframework.transaction/3.2.2/org/springframework/transaction/interceptor/TransactionInterceptor.java#TransactionInterceptor[/url]
[b][size=medium]创建BeanFactoryTransactionAttributeSourceAdvisor的beanDefinition[/size][/b]
d.定义BeanFactoryTransactionAttributeSourceAdvisor-[b][color=green]事务集成到业务bean,连接中介类[/color][/b]
[img]http://dl2.iteye.com/upload/attachment/0123/9287/a9f6d1c0-b319-3120-9cf8-e95e300fa823.png[/img]
// Create the TransactionAttributeSourceAdvisor definition.
RootBeanDefinition advisorDef = new RootBeanDefinition(BeanFactoryTransactionAttributeSourceAdvisor.class);
advisorDef.setSource(eleSource);
advisorDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
advisorDef.getPropertyValues().add("transactionAttributeSource", new RuntimeBeanReference(sourceName));
advisorDef.getPropertyValues().add("adviceBeanName", interceptorName);
if (element.hasAttribute("order")) {
advisorDef.getPropertyValues().add("order", element.getAttribute("order"));
}
parserContext.getRegistry().registerBeanDefinition(txAdvisorBeanName, advisorDef);
创建TransactionAttributeSourceAdvisor定义
BeanFactoryTransactionAttributeSourceAdvisor源码：
[url]http://grepcode.com/file/repository.springsource.com/org.springframework/org.springframework.transaction/3.2.2/org/springframework/transaction/interceptor/BeanFactoryTransactionAttributeSourceAdvisor.java?av=f[/url]
BeanFactoryTransactionAttributeSourceAdvisor是一个标识类，使其能够被后置处理器(InfrastructureAdvisorAutoProxyCreator见(a)出分析)识别。
具体分析见：
http://www.cnblogs.com/youzhibing/p/6414780.html
持有对象TransactionAttributeSourcePointcut
[img]http://dl2.iteye.com/upload/attachment/0123/9301/ef7d446c-7ca8-3545-b6ec-411e16afd54e.png[/img]
public boolean matches(Method method, Class targetClass) {
TransactionAttributeSource tas = getTransactionAttributeSource();
return (tas == null || tas.getTransactionAttribute(method, targetClass) != null);
}后置处理器中调用此方法，判断bean或method是否适合此advisor
TransactionAttributeSourcePointcut源码见
[url]http://grepcode.com/file/repository.springsource.com/org.springframework/org.springframework.transaction/3.1.2/org/springframework/transaction/interceptor/TransactionAttributeSourcePointcut.java#TransactionAttributeSourcePointcut[/url]
[b][size=medium]创建CompositeComponentDefinition的beanDefinition[/size][/b]
e.定义组件之间的关系bean
CompositeComponentDefinition compositeDef = new CompositeComponentDefinition(element.getTagName(), eleSource);
compositeDef.addNestedComponent(new BeanComponentDefinition(sourceDef, sourceName));
compositeDef.addNestedComponent(new BeanComponentDefinition(interceptorDef, interceptorName));
compositeDef.addNestedComponent(new BeanComponentDefinition(advisorDef, txAdvisorBeanName));
parserContext.registerComponent(compositeDef);该类的具体作用是什么？
定义事务处理之间的关系？
[size=large]断点4:[/size]
总结：
条件语句里面创建了3个bean定义（TransactionAttributeSource ，TransactionInterceptor，TransactionAttributeSourceAdvisor ）,将3个类组合嵌入compositeDef中,代表整个<tx:annotation-driven transaction-manager=”transactionManager” />
还创建了一个后置处理器，bean实例化后，创建事务代理
创建3个定义或者后置处理器的过程中，多处可以继续跟踪代码，如如何创建aopProxy代理，transactioninterceptor中的invoke方法是如何执行的等等。限于篇幅，这里进一步跟踪，后续补上
[size=large]2.2 @Transactionl[/size]
事务属性来源，主要在TransactionAttributeSource中判断bean或者method中是否有注解
3.代理的使用-使用中遇到的常见问题
参考：
https://www.ibm.com/developerworks/cn/education/opensource/os-cn-spring-trans/
http://www.myexception.cn/open-source/1942796.html
http://www.codeceo.com/article/software-outsourcing-and-lover.html
http://blog.csdn.net/qq418517226/article/details/51282035
http://jinnianshilongnian.iteye.com/blog/1901694
http://www.cnblogs.com/wade-luffy/p/6080183.html Spring事务解析2-标签解析
http://jinnianshilongnian.iteye.com/blog/1508018 TransactionAttributeSource
http://lgbolgger.iteye.com/blog/2180251 Spring事务源码分析（一）Spring事务入门
