【Seata源码学习 】 AT模式 第一阶段 @GlobalTransaction的扫描

源码学习 】 AT模式 第一阶段 @GlobalTransaction的扫描"/>

【Seata源码学习 】 AT模式 第一阶段 @GlobalTransaction的扫描

1. SeataAutoConfiguration 自动配置类的加载

基于SpringBoot的starter机制，在应用上下文启动时，会加载SeataAutoConfiguration自动配置类

# Auto Configure
org.springframework.boot.autoconfigure.EnableAutoConfiguration=io.seata.spring.boot.autoconfigure.SeataAutoConfiguration

此配置类将会往应用上下文中注册四个组件

从名字就知道，此组件负责扫描@GlobalTransaction

此类的继承关系如下图所示

2. @GlobalTransaction注解扫描

父类 AbstractAutoProxyCreator 实现了 SmartInstantiationAwareBeanPostProcessor 接口,重写了 postProcessAfterInitialization 方法

	public Object postProcessAfterInitialization(@Nullable Object bean, String beanName) {if (bean != null) {Object cacheKey = getCacheKey(bean.getClass(), beanName);if (this.earlyProxyReferences.remove(cacheKey) != bean) {return wrapIfNecessary(bean, beanName, cacheKey);}}return bean;}

io.seata.spring.annotation.GlobalTransactionScanner#wrapIfNecessary

protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) {// do checkersif (!doCheckers(bean, beanName)) {return bean;}try {synchronized (PROXYED_SET) {if (PROXYED_SET.contains(beanName)) {return bean;}interceptor = null;//check TCC proxyif (TCCBeanParserUtils.isTccAutoProxy(bean, beanName, applicationContext)) {// init tcc fence clean task if enable useTccFenceTCCBeanParserUtils.initTccFenceCleanTask(TCCBeanParserUtils.getRemotingDesc(beanName), applicationContext);//TCC interceptor, proxy bean of sofa:reference/dubbo:reference, and LocalTCCinterceptor = new TccActionInterceptor(TCCBeanParserUtils.getRemotingDesc(beanName));ConfigurationCache.addConfigListener(ConfigurationKeys.DISABLE_GLOBAL_TRANSACTION,(ConfigurationChangeListener)interceptor);} else {//很实用的两个工具类//查找类的原始类 而非代理类Class<?> serviceInterface = SpringProxyUtils.findTargetClass(bean);//查找类所有实现的接口Class<?>[] interfacesIfJdk = SpringProxyUtils.findInterfaces(bean);// 类上面是否有GlobalTransactional 注解  方法上面是否有标 GlobalTransactional GlobalLock注解if (!existsAnnotation(new Class[]{serviceInterface})// 接口上面是否有GlobalTransactional 注解  方法上面是否有标 GlobalTransactional GlobalLock注解&& !existsAnnotation(interfacesIfJdk)) {return bean;}//如果有 成员变量 MethodInterceptor  interceptor 赋值if (globalTransactionalInterceptor == null) {globalTransactionalInterceptor = new GlobalTransactionalInterceptor(failureHandlerHook);ConfigurationCache.addConfigListener(ConfigurationKeys.DISABLE_GLOBAL_TRANSACTION,(ConfigurationChangeListener)globalTransactionalInterceptor);}interceptor = globalTransactionalInterceptor;}LOGGER.info("Bean[{}] with name [{}] would use interceptor [{}]", bean.getClass().getName(), beanName, interceptor.getClass().getName());if (!AopUtils.isAopProxy(bean)) {//当前类没有被AOP代理过bean = super.wrapIfNecessary(bean, beanName, cacheKey);} else {//当前类被AOP代理过//AdvisedSupport对象是Spring框架中用于支持AOP的核心类之一，它封装了AOP代理的配置信息和运行时状态。// 通过获取AdvisedSupport对象，可以进一步了解和操作代理对象的AOP配置AdvisedSupport advised = SpringProxyUtils.getAdvisedSupport(bean);// AdvisedSupport ：  Advisor 一对多//Spring AOP 中的 Advisor 是一种拦截器，// 它可以拦截特定的方法调用，并在方法调用前、后或异常时执行一些特定的操作//getAdvicesAndAdvisorsForBean 方法将返回我们上一步创建的GlobalTransactionalInterceptor//buildAdvisors 方法 将 MethodInterceptor 构建成一个  Advisor 用于后续创建代理类Advisor[] advisor = buildAdvisors(beanName, getAdvicesAndAdvisorsForBean(null, null, null));int pos;for (Advisor avr : advisor) {// Find the position based on the advisor's order, and add to advisors by pos//调整advisor 的位置pos = findAddSeataAdvisorPosition(advised, avr);advised.addAdvisor(pos, avr);}}//记录已经代理过的beanNamePROXYED_SET.add(beanName);//返回当前beanreturn bean;}} catch (Exception exx) {throw new RuntimeException(exx);}}

创建代理类情况一 ：当前bean已经被AOP代理过

通常@GlobalTransation注解标注在业务层，而业务层的bean大多走到这已经被AOP代理过。如果你项目中使用的是MybatisPlus，那么通常会被org.springframework.transaction.interceptor.BeanFactoryTransactionAttributeSourceAdvisor创建代理类

AdvisedSupport 添加一个Advisor( GlobalTransactionalInterceptor )后，将之前就被代理过的bean返回,你可能会好奇，添加一个 Advisor 就不管了 ？ 最终谁来调用呢 ？

class org.springframework.aop.aspectj.annotation.AnnotationAwareAspectJAutoProxyCreator

继承了 AspectJAwareAdvisorAutoProxyCreator 继承了 AbstractAdvisorAutoProxyCreator 继承了 AbstractAutoProxyCreator 实现了 SmartInstantiationAwareBeanPostProcessor，

将在每个bean实例化后执行 postProcessAfterInitialization 方法，

org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#postProcessAfterInitialization

org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#wrapIfNecessary

org.springframework.aop.framework.autoproxy.AbstractAdvisorAutoProxyCreator#getAdvicesAndAdvisorsForBean

org.springframework.aop.framework.autoproxy.AbstractAdvisorAutoProxyCreator#findEligibleAdvisors

最终将找到 org.springframework.transaction.interceptor.BeanFactoryTransactionAttributeSourceAdvisor:

	protected List<Advisor> findEligibleAdvisors(Class<?> beanClass, String beanName) {//查找所有的AdvisorList<Advisor> candidateAdvisors = findCandidateAdvisors();//判断当前bean是否满足Advisor的拦截要求List<Advisor> eligibleAdvisors = findAdvisorsThatCanApply(candidateAdvisors, beanClass, beanName);extendAdvisors(eligibleAdvisors);if (!eligibleAdvisors.isEmpty()) {eligibleAdvisors = sortAdvisors(eligibleAdvisors);}return eligibleAdvisors;}

Advisor 你可以理解为绑定了ponitcut的Advice 容器 ， BeanFactoryTransactionAttributeSourceAdvisor绑定的为 TransactionAttributeSourcePointcut

方法的匹配规则

@Overridepublic boolean matches(Method method, Class<?> targetClass) {TransactionAttributeSource tas = getTransactionAttributeSource();return (tas == null || tas.getTransactionAttribute(method, targetClass) != null);}

类的匹配规则

org.springframework.transaction.annotation.SpringTransactionAnnotationParser#isCandidateClass

@Overridepublic boolean isCandidateClass(Class<?> targetClass) {//当前类上是否有 Transactional 注解return AnnotationUtils.isCandidateClass(targetClass, Transactional.class);}

而获取方法是的代码如下

org.springframework.aop.support.AopUtils#canApply(org.springframework.aop.Pointcut, java.lang.Class<?>, boolean)

		for (Class<?> clazz : classes) {//getAllDeclaredMethods 获取当前类包括父类的所有方法Method[] methods = ReflectionUtils.getAllDeclaredMethods(clazz);for (Method method : methods) {if (introductionAwareMethodMatcher != null ?introductionAwareMethodMatcher.matches(method, targetClass, hasIntroductions) :methodMatcher.matches(method, targetClass)) {return true;}}}

我们使用的MybatisPlus通常业务层的类会继承ServiceImpl，而ServiceImpl类中有不少方法就是标注了@Transactional注解，因此 BeanFactoryTransactionAttributeSourceAdvisor 对当前的业务层bean来说，是满足匹配规则的

回到

org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#wrapIfNecessary

protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) {if (StringUtils.hasLength(beanName) && this.targetSourcedBeans.contains(beanName)) {return bean;}if (Boolean.FALSE.equals(this.advisedBeans.get(cacheKey))) {return bean;}if (isInfrastructureClass(bean.getClass()) || shouldSkip(bean.getClass(), beanName)) {this.advisedBeans.put(cacheKey, Boolean.FALSE);return bean;}// Create proxy if we have advice.//拿到 BeanFactoryTransactionAttributeSourceAdvisor Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);if (specificInterceptors != DO_NOT_PROXY) {this.advisedBeans.put(cacheKey, Boolean.TRUE);//创建代理类Object proxy = createProxy(bean.getClass(), beanName, specificInterceptors, new SingletonTargetSource(bean));this.proxyTypes.put(cacheKey, proxy.getClass());return proxy;}this.advisedBeans.put(cacheKey, Boolean.FALSE);return bean;}

protected Object createProxy(Class<?> beanClass, @Nullable String beanName,@Nullable Object[] specificInterceptors, TargetSource targetSource) {if (this.beanFactory instanceof ConfigurableListableBeanFactory) {AutoProxyUtils.exposeTargetClass((ConfigurableListableBeanFactory) this.beanFactory, beanName, beanClass);}//创建 ProxyFactory 对象，ProxyFactory proxyFactory = new ProxyFactory();proxyFactory.copyFrom(this);if (!proxyFactory.isProxyTargetClass()) {if (shouldProxyTargetClass(beanClass, beanName)) {proxyFactory.setProxyTargetClass(true);}else {evaluateProxyInterfaces(beanClass, proxyFactory);}}//创建 Advisor 链Advisor[] advisors = buildAdvisors(beanName, specificInterceptors);proxyFactory.addAdvisors(advisors);//设置代理目标类proxyFactory.setTargetSource(targetSource);customizeProxyFactory(proxyFactory);proxyFactory.setFrozen(this.freezeProxy);if (advisorsPreFiltered()) {proxyFactory.setPreFiltered(true);}//创建目标代理类return proxyFactory.getProxy(getProxyClassLoader());}

通常情况下会使用CGLB进行创建代理类

org.springframework.aop.framework.CglibAopProxy#getProxy(java.lang.ClassLoader)

public Object getProxy(@Nullable ClassLoader classLoader) {if (logger.isTraceEnabled()) {logger.trace("Creating CGLIB proxy: " + this.advised.getTargetSource());}try {Class<?> rootClass = this.advised.getTargetClass();Assert.state(rootClass != null, "Target class must be available for creating a CGLIB proxy");Class<?> proxySuperClass = rootClass;if (rootClass.getName().contains(ClassUtils.CGLIB_CLASS_SEPARATOR)) {proxySuperClass = rootClass.getSuperclass();Class<?>[] additionalInterfaces = rootClass.getInterfaces();for (Class<?> additionalInterface : additionalInterfaces) {this.advised.addInterface(additionalInterface);}}// Validate the class, writing log messages as necessary.validateClassIfNecessary(proxySuperClass, classLoader);// Configure CGLIB Enhancer...Enhancer enhancer = createEnhancer();if (classLoader != null) {enhancer.setClassLoader(classLoader);if (classLoader instanceof SmartClassLoader &&((SmartClassLoader) classLoader).isClassReloadable(proxySuperClass)) {enhancer.setUseCache(false);}}enhancer.setSuperclass(proxySuperClass);enhancer.setInterfaces(AopProxyUtilspleteProxiedInterfaces(this.advised));enhancer.setNamingPolicy(SpringNamingPolicy.INSTANCE);enhancer.setStrategy(new ClassLoaderAwareGeneratorStrategy(classLoader));//设置默认回调函数Callback[] callbacks = getCallbacks(rootClass);Class<?>[] types = new Class<?>[callbacks.length];for (int x = 0; x < types.length; x++) {types[x] = callbacks[x].getClass();}// fixedInterceptorMap only populated at this point, after getCallbacks call above//默认回调函数匹配规则enhancer.setCallbackFilter(new ProxyCallbackFilter(this.advised.getConfigurationOnlyCopy(), this.fixedInterceptorMap, this.fixedInterceptorOffset));enhancer.setCallbackTypes(types);// Generate the proxy class and create a proxy instance.//增强目标代理类return createProxyClassAndInstance(enhancer, callbacks);}catch (CodeGenerationException | IllegalArgumentException ex) {throw new AopConfigException("Could not generate CGLIB subclass of " + this.advised.getTargetClass() +": Common causes of this problem include using a final class or a non-visible class",ex);}catch (Throwable ex) {// TargetSource.getTarget() failedthrow new AopConfigException("Unexpected AOP exception", ex);}}

private Callback[] getCallbacks(Class<?> rootClass) throws Exception {// Parameters used for optimization choices...boolean exposeProxy = this.advised.isExposeProxy();boolean isFrozen = this.advised.isFrozen();boolean isStatic = this.advised.getTargetSource().isStatic();// Choose an "aop" interceptor (used for AOP calls).//用于aop的回调函数Callback aopInterceptor = new DynamicAdvisedInterceptor(this.advised);// Choose a "straight to target" interceptor. (used for calls that are// unadvised but can return this). May be required to expose the proxy.Callback targetInterceptor;if (exposeProxy) {targetInterceptor = (isStatic ?new StaticUnadvisedExposedInterceptor(this.advised.getTargetSource().getTarget()) :new DynamicUnadvisedExposedInterceptor(this.advised.getTargetSource()));}else {targetInterceptor = (isStatic ?new StaticUnadvisedInterceptor(this.advised.getTargetSource().getTarget()) :new DynamicUnadvisedInterceptor(this.advised.getTargetSource()));}// Choose a "direct to target" dispatcher (used for// unadvised calls to static targets that cannot return this).Callback targetDispatcher = (isStatic ?new StaticDispatcher(this.advised.getTargetSource().getTarget()) : new SerializableNoOp());//6个默认的回调函数Callback[] mainCallbacks = new Callback[] {aopInterceptor,  // for normal advicetargetInterceptor,  // invoke target without considering advice, if optimizednew SerializableNoOp(),  // no override for methods mapped to thistargetDispatcher, this.advisedDispatcher,new EqualsInterceptor(this.advised),new HashCodeInterceptor(this.advised)};Callback[] callbacks;// If the target is a static one and the advice chain is frozen,// then we can make some optimizations by sending the AOP calls// direct to the target using the fixed chain for that method.if (isStatic && isFrozen) {Method[] methods = rootClass.getMethods();Callback[] fixedCallbacks = new Callback[methods.length];this.fixedInterceptorMap = new HashMap<>(methods.length);// TODO: small memory optimization here (can skip creation for methods with no advice)for (int x = 0; x < methods.length; x++) {Method method = methods[x];//将 advisor集合转化为 MethodInterceptor 集合List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, rootClass);fixedCallbacks[x] = new FixedChainStaticTargetInterceptor(chain, this.advised.getTargetSource().getTarget(), this.advised.getTargetClass());this.fixedInterceptorMap.put(method, x);}// Now copy both the callbacks from mainCallbacks// and fixedCallbacks into the callbacks array.callbacks = new Callback[mainCallbacks.length + fixedCallbacks.length];System.arraycopy(mainCallbacks, 0, callbacks, 0, mainCallbacks.length);System.arraycopy(fixedCallbacks, 0, callbacks, mainCallbacks.length, fixedCallbacks.length);this.fixedInterceptorOffset = mainCallbacks.length;}else {callbacks = mainCallbacks;}return callbacks;}

看一下callbackFilter 设置的 callback回调规则

public int accept(Method method) {if (AopUtils.isFinalizeMethod(method)) {logger.trace("Found finalize() method - using NO_OVERRIDE");return NO_OVERRIDE; //如果是finalize方法，执行targetInterceptor回调函数，相当于什么都没做}//方法是否在Advised接口上声明。如果是，则返回DISPATCH_ADVISED，表示需要回调 advisedDispatcher 函数if (!this.advised.isOpaque() && method.getDeclaringClass().isInterface() &&method.getDeclaringClass().isAssignableFrom(Advised.class)) {if (logger.isTraceEnabled()) {logger.trace("Method is declared on Advised interface: " + method);}return DISPATCH_ADVISED;}// 检查方法是否为equals()方法或hashCode()方法，如果是，则分别返回INVOKE_EQUALS和INVOKE_HASHCODE，表示需要调用EqualsInterceptor 回调函数或 HashCodeInterceptor 回调函数if (AopUtils.isEqualsMethod(method)) {if (logger.isTraceEnabled()) {logger.trace("Found 'equals' method: " + method);}return INVOKE_EQUALS;}// We must always calculate hashCode based on the proxy.if (AopUtils.isHashCodeMethod(method)) {if (logger.isTraceEnabled()) {logger.trace("Found 'hashCode' method: " + method);}return INVOKE_HASHCODE;}//获取目标类Class<?> targetClass = this.advised.getTargetClass();// Proxy is not yet available, but that shouldn't matter.//获取方法拦截器链List<?> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);boolean haveAdvice = !chain.isEmpty();boolean exposeProxy = this.advised.isExposeProxy();boolean isStatic = this.advised.getTargetSource().isStatic();boolean isFrozen = this.advised.isFrozen();//chain  不为空 且未冻结if (haveAdvice || !isFrozen) {// If exposing the proxy, then AOP_PROXY must be used.if (exposeProxy) {if (logger.isTraceEnabled()) {logger.trace("Must expose proxy on advised method: " + method);}return AOP_PROXY; // 使用aopInterceptor 回调函数}// Check to see if we have fixed interceptor to serve this method.// Else use the AOP_PROXY.//方法是静态的、代理已被冻结，并且存在固定的拦截器来处理该方法，则返回固定拦截器的索引加上固定拦截器偏移量。这段代码用于判断是否存在固定的拦截器来处理该方法，并返回相应的处理方式。如果存在固定的拦截器，则返回固定拦截器的索引加上偏移量；否则，返回AOP_PROXY，表示需要使用AOP代理进行处理。if (isStatic && isFrozen && this.fixedInterceptorMap.containsKey(method)) {if (logger.isTraceEnabled()) {logger.trace("Method has advice and optimizations are enabled: " + method);}// We know that we are optimizing so we can use the FixedStaticChainInterceptors.int index = this.fixedInterceptorMap.get(method);return (index + this.fixedInterceptorOffset);}else {if (logger.isTraceEnabled()) {logger.trace("Unable to apply any optimizations to advised method: " + method);}return AOP_PROXY;}}else {// See if the return type of the method is outside the class hierarchy of the target type.// If so we know it never needs to have return type massage and can use a dispatcher.// If the proxy is being exposed, then must use the interceptor the correct one is already// configured. If the target is not static, then we cannot use a dispatcher because the// target needs to be explicitly released after the invocation.if (exposeProxy || !isStatic) {return INVOKE_TARGET;}Class<?> returnType = method.getReturnType();if (targetClass != null && returnType.isAssignableFrom(targetClass)) {if (logger.isTraceEnabled()) {logger.trace("Method return type is assignable from target type and " +"may therefore return 'this' - using INVOKE_TARGET: " + method);}return INVOKE_TARGET;}else {if (logger.isTraceEnabled()) {logger.trace("Method return type ensures 'this' cannot be returned - " +"using DISPATCH_TARGET: " + method);}return DISPATCH_TARGET;}}}

在回到之前那个问题，AdvisedSupport 添加一个Advisor( GlobalTransactionalInterceptor )后，将之前就被代理过的bean返回,当前bean的业务方法在执行时，就会由callbackFilter匹配上 aopInterceptor 回调函数并执行

Callback aopInterceptor = new DynamicAdvisedInterceptor(this.advised);

DynamicAdvisedInterceptor 是 CglibAopProxy 的静态内部类 ，实现了 MethodInterceptor 接口

	private static class DynamicAdvisedInterceptor implements MethodInterceptor, Serializable {private final AdvisedSupport advised;public DynamicAdvisedInterceptor(AdvisedSupport advised) {this.advised = advised;}@Override@Nullablepublic Object intercept(Object proxy, Method method, Object[] args, MethodProxy methodProxy) throws Throwable {Object oldProxy = null;boolean setProxyContext = false;Object target = null;TargetSource targetSource = this.advised.getTargetSource();try {if (this.advised.exposeProxy) {// Make invocation available if necessary.oldProxy = AopContext.setCurrentProxy(proxy);setProxyContext = true;}// Get as late as possible to minimize the time we "own" the target, in case it comes from a pool...target = targetSource.getTarget();Class<?> targetClass = (target != null ? target.getClass() : null);// 获取方法拦截器链List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);Object retVal;// Check whether we only have one InvokerInterceptor: that is,// no real advice, but just reflective invocation of the target.if (chain.isEmpty() && Modifier.isPublic(method.getModifiers())) {// We can skip creating a MethodInvocation: just invoke the target directly.// Note that the final invoker must be an InvokerInterceptor, so we know// it does nothing but a reflective operation on the target, and no hot// swapping or fancy proxying.Object[] argsToUse = AopProxyUtils.adaptArgumentsIfNecessary(method, args);retVal = methodProxy.invoke(target, argsToUse);}else {// We need to create a method invocation...//拦截器链路调用retVal = new CglibMethodInvocation(proxy, target, method, args, targetClass, chain, methodProxy).proceed();}//返回值处理retVal = processReturnType(proxy, target, method, retVal);return retVal;}finally {if (target != null && !targetSource.isStatic()) {targetSource.releaseTarget(target);}if (setProxyContext) {// Restore old proxy.AopContext.setCurrentProxy(oldProxy);}}}@Overridepublic boolean equals(@Nullable Object other) {return (this == other ||(other instanceof DynamicAdvisedInterceptor &&this.advised.equals(((DynamicAdvisedInterceptor) other).advised)));}/*** CGLIB uses this to drive proxy creation.*/@Overridepublic int hashCode() {return this.advised.hashCode();}}

跟进 org.springframework.aop.framework.CglibAopProxy.CglibMethodInvocation#proceed

		@Override@Nullablepublic Object proceed() throws Throwable {try {return super.proceed();}catch (RuntimeException ex) {throw ex;}catch (Exception ex) {if (ReflectionUtils.declaresException(getMethod(), ex.getClass())) {throw ex;}else {throw new UndeclaredThrowableException(ex);}}}

父类 org.springframework.aop.framework.ReflectiveMethodInvocation#proceed

public Object proceed() throws Throwable {// We start with an index of -1 and increment early.// 如果当前拦截器链已经是最后一个了 调用目标方法if (this.currentInterceptorIndex == this.interceptorsAndDynamicMethodMatchers.size() - 1) {return invokeJoinpoint();}// currentInterceptorIndex 从 -1 开始，此时获取下表为0的方法拦截器Object interceptorOrInterceptionAdvice =this.interceptorsAndDynamicMethodMatchers.get(++this.currentInterceptorIndex);if (interceptorOrInterceptionAdvice instanceof InterceptorAndDynamicMethodMatcher) {// Evaluate dynamic method matcher here: static part will already have// been evaluated and found to match.InterceptorAndDynamicMethodMatcher dm =(InterceptorAndDynamicMethodMatcher) interceptorOrInterceptionAdvice;Class<?> targetClass = (this.targetClass != null ? this.targetClass : this.method.getDeclaringClass());if (dm.methodMatcher.matches(this.method, targetClass, this.arguments)) {return dm.interceptor.invoke(this);}else {// Dynamic matching failed.// Skip this interceptor and invoke the next in the chain.return proceed();}}else {// It's an interceptor, so we just invoke it: The pointcut will have// been evaluated statically before this object was constructed.//拦截器在此处调用  注意此处把 this 给传递过去了，每个拦截器在执行完毕后又会调用 this.proceed 进行递归调用return ((MethodInterceptor) interceptorOrInterceptionAdvice).invoke(this);}}

创建代理类情况二 ：当前bean已经未被AOP代理

回调 io.seata.spring.annotation.GlobalTransactionScanner#wrapIfNecessary

    if (!AopUtils.isAopProxy(bean)) {//如果当前类未被代理，则调用父类的wrapIfNecessary 方法bean = super.wrapIfNecessary(bean, beanName, cacheKey);} else {AdvisedSupport advised = SpringProxyUtils.getAdvisedSupport(bean);Advisor[] advisor = buildAdvisors(beanName, getAdvicesAndAdvisorsForBean(null, null, null));for (Advisor avr : advisor) {advised.addAdvisor(0, avr);}}

protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) {if (StringUtils.hasLength(beanName) && this.targetSourcedBeans.contains(beanName)) {return bean;}if (Boolean.FALSE.equals(this.advisedBeans.get(cacheKey))) {return bean;}if (isInfrastructureClass(bean.getClass()) || shouldSkip(bean.getClass(), beanName)) {this.advisedBeans.put(cacheKey, Boolean.FALSE);return bean;}// Create proxy if we have advice.//调用子类 重写的 io.seata.spring.annotation.GlobalTransactionScanner#getAdvicesAndAdvisorsForBean 方法// 返回 GlobalTransactionalInterceptorObject[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);if (specificInterceptors != DO_NOT_PROXY) {this.advisedBeans.put(cacheKey, Boolean.TRUE);Object proxy = createProxy(bean.getClass(), beanName, specificInterceptors, new SingletonTargetSource(bean));this.proxyTypes.put(cacheKey, proxy.getClass());return proxy;}this.advisedBeans.put(cacheKey, Boolean.FALSE);return bean;}

调用org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#createProxy，

创建 ProxyFactory 对象，设置目标代理类，添加advisors，最终创建代理类，对目标方法进行拦截来增强目标方法

protected Object createProxy(Class<?> beanClass, @Nullable String beanName,@Nullable Object[] specificInterceptors, TargetSource targetSource) {if (this.beanFactory instanceof ConfigurableListableBeanFactory) {AutoProxyUtils.exposeTargetClass((ConfigurableListableBeanFactory) this.beanFactory, beanName, beanClass);}ProxyFactory proxyFactory = new ProxyFactory();proxyFactory.copyFrom(this);if (!proxyFactory.isProxyTargetClass()) {if (shouldProxyTargetClass(beanClass, beanName)) {proxyFactory.setProxyTargetClass(true);}else {evaluateProxyInterfaces(beanClass, proxyFactory);}}//构建Advisor[] 用于方法拦截Advisor[] advisors = buildAdvisors(beanName, specificInterceptors);proxyFactory.addAdvisors(advisors);//设置被代理类proxyFactory.setTargetSource(targetSource);customizeProxyFactory(proxyFactory);proxyFactory.setFrozen(this.freezeProxy);if (advisorsPreFiltered()) {proxyFactory.setPreFiltered(true);}//创建代理对象 最终底层通过 JDK动态代理或CGILIB代理创建代理对象return proxyFactory.getProxy(getProxyClassLoader());}

3.流程图