SpringAOP——源码
一、找到代理对象初始化的地方
1 @Configuration 2 @EnableAspectJAutoProxy 3 public class Main { 4 5 public static void main(String[] args){ 6 AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(); 7 context.scan("com.app.aop"); 8 context.refresh(); 9 Xxable a = (Xxable)context.getBean("a"); 10 B b = (B) context.getBean("b"); 11 a.xx(); 12 b.xx(); 13 System.out.println(a.getClass().getName()); 14 System.out.println(b.getClass().getName()); 15 } 16 }
在第9行断点发现，IOC容器初始化后，IOC容器中存放的已经是代理对象proxy obejct
根据动态代理分析：JDK动态代理是先创建targetobject然后将targetobject组合到proxyObject中，所以创建proxy object必是在target object初始化之后
通过前面bean初始化知道在DI之后才bean基本初始化完成，也就是proxy object的产生是在DI之后，
最后在bean初始化完成后，调用BeanPostProcessor时找到了proxy object产生的地方
/* org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#doCreateBean */ protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final @Nullable Object[] args) throws BeanCreationException { ... //这里实现DI populateBean(beanName, mbd, instanceWrapper); //DI完成后执行BeanPostProcessor exposedObject = initializeBean(beanName, exposedObject, mbd); ... } /* org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory#initializeBean(java.lang.String, java.lang.Object, org.springframework.beans.factory.support.RootBeanDefinition) */ protected Object initializeBean(final String beanName, final Object bean, @Nullable RootBeanDefinition mbd) { ... //调用所有BeanPostProcessor前置方法BeanPostProcessor.postProcessBeforeInitialization wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName); ... //调用所有BeanPostProcessor前置方法BeanPostProcessor.postProcessAfterInitialization //AOP代理对象就是这里初始化的 wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName); ... }
具体的实现AnnotationAwareAspectJAutoProxyCreator.postProcessAfterInitialization
二、AnnotationAwareAspectJAutoProxyCreator
AnnoatiowareAspectJAutoProxyCreator.postprocessAfterInitialzation
/* org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#postProcessAfterInitialization */ public Object postProcessAfterInitialization(@Nullable Object bean, String beanName) { if (bean != null) { //feactoryBean beanName = &beanName //Bean beanName = beanName Object cacheKey = getCacheKey(bean.getClass(), beanName); if (this.earlyProxyReferences.remove(cacheKey) != bean) { //创建proxy object return wrapIfNecessary(bean, beanName, cacheKey); } } return bean; } protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) { //跳过自定义代理的Bean例如有个Bean使用AspectJ实现AOP，不需要使用SpringAOP再来代理了
（设置BeanPostProcessor.targetSourcedBeans.add） //避免自定义代理后，又默认代理一遍 if (StringUtils.hasLength(beanName) && this.targetSourcedBeans.contains(beanName)) { return bean; } //skip不能被代理的Bean（设置BeanPostProcessor.before里面advisedBeans.put） //例如PointCut.class的实例Bean if (Boolean.FALSE.equals(this.advisedBeans.get(cacheKey))) { return bean; } //再次验证上一步 if (isInfrastructureClass(bean.getClass()) || shouldSkip(bean.getClass(), beanName)) { this.advisedBeans.put(cacheKey, Boolean.FALSE); return bean; } // Create proxy if we have advice. //如果有advisor获取所有的advisors，然后筛选出class对应joinpoint的advisors Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null); //advisors不为空初始化proxy object if (specificInterceptors != DO_NOT_PROXY) { this.advisedBeans.put(cacheKey, Boolean.TRUE); //创建代理对象proxy object 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; }
Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);获取所有的advisors
/* org.springframework.aop.framework.autoproxy.AbstractAdvisorAutoProxyCreator#getAdvicesAndAdvisorsForBean */ protected Object[] getAdvicesAndAdvisorsForBean( Class<?> beanClass, String beanName, @Nullable TargetSource targetSource) { //统计advice List<Advisor> advisors = findEligibleAdvisors(beanClass, beanName); if (advisors.isEmpty()) { return DO_NOT_PROXY; } return advisors.toArray(); } protected List<Advisor> findEligibleAdvisors(Class<?> beanClass, String beanName) { //查找所有Advisor，用Bean创建的Advisor+aspectBean中的advisor方法 List<Advisor> candidateAdvisors = findCandidateAdvisors(); //根据class中方法匹配对应的Advisor,过滤当前bean TargetClass与Advisor对应的pointCut相匹配的Advisor List<Advisor> eligibleAdvisors = findAdvisorsThatCanApply(candidateAdvisors, beanClass, beanName); //加入一个默认的ExposeInvocationInterceptor.ADVISOR //后面责任链模式执行代理方法,这个advisor就位于责任链首位了，第一个需要被执行的advisor //作用就是记录target object的方法（ThreadLocal实现），便于调整五种advice的执行循序的实现 extendAdvisors(eligibleAdvisors); if (!eligibleAdvisors.isEmpty()) { //一开始我以为是倒序后来发现错了，默认先比较order值 //默认advisor。order < 0 放首位 //然后调整afterThrowAdvice>afterRuturningAdvice>afterAdivce>RoundAdvice>BeforeAdvice eligibleAdvisors = sortAdvisors(eligibleAdvisors); } return eligibleAdvisors; }
List<Advisor> candidateAdvisors = findCandidateAdvisors();：获取所有的advisors Bean创建的advisor+扫描aspect中的advisor方法
/* org.springframework.aop.aspectj.annotation.AnnotationAwareAspectJAutoProxyCreator#findCandidateAdvisors */ protected List<Advisor> findCandidateAdvisors() { // Add all the Spring advisors found according to superclass rules. //用Bean创建的Advice List<Advisor> advisors = super.findCandidateAdvisors(); // Build Advisors for all AspectJ aspects in the bean factory. if (this.aspectJAdvisorsBuilder != null) { //加上aspect的Bean中的Advice方法 advisors.addAll(this.aspectJAdvisorsBuilder.buildAspectJAdvisors()); } return advisors; }
this.aspectJAdvisorsBuilder.buildAspectJAdvisors():获取aspect中声明的advisors
/* org.springframework.aop.aspectj.annotation.BeanFactoryAspectJAdvisorsBuilder#buildAspectJAdvisors */ public List<Advisor> buildAspectJAdvisors() { List<String> aspectNames = this.aspectBeanNames; if (aspectNames == null) { synchronized (this) { aspectNames = this.aspectBeanNames; if (aspectNames == null) { List<Advisor> advisors = new ArrayList<>(); aspectNames = new ArrayList<>(); //获取beanfactory中所有的beanName，遍历allBeanNamesByType获得 String[] beanNames = BeanFactoryUtils.beanNamesForTypeIncludingAncestors( this.beanFactory, Object.class, true, false); for (String beanName : beanNames) { if (!isEligibleBean(beanName)) { continue; } // We must be careful not to instantiate beans eagerly as in this case they // would be cached by the Spring container but would not have been weaved. //根据beanName过去bean的类型Type Class<?> beanType = this.beanFactory.getType(beanName); if (beanType == null) { continue; } // 根据beanType筛选出切面aspect： // class被@Aspect注解，且不是AspectJ编译器生成的类（通过魔数判断） if (this.advisorFactory.isAspect(beanType)) { //缓存aspectBean的beanName aspectNames.add(beanName); AspectMetadata amd = new AspectMetadata(beanType, beanName); if (amd.getAjType().getPerClause().getKind() == PerClauseKind.SINGLETON) { MetadataAwareAspectInstanceFactory factory = new BeanFactoryAspectInstanceFactory(this.beanFactory, beanName); //从aspect中定义的advisor List<Advisor> classAdvisors = this.advisorFactory.getAdvisors(factory); if (this.beanFactory.isSingleton(beanName)) { //单例缓存advisor this.advisorsCache.put(beanName, classAdvisors); } else { //原型缓存factory this.aspectFactoryCache.put(beanName, factory); } advisors.addAll(classAdvisors); } else { // Per target or per this. if (this.beanFactory.isSingleton(beanName)) { throw new IllegalArgumentException("Bean with name '" + beanName + "' is a singleton, but aspect instantiation model is not singleton"); } MetadataAwareAspectInstanceFactory factory = new PrototypeAspectInstanceFactory(this.beanFactory, beanName); this.aspectFactoryCache.put(beanName, factory); advisors.addAll(this.advisorFactory.getAdvisors(factory)); } } } this.aspectBeanNames = aspectNames; return advisors; } } } if (aspectNames.isEmpty()) { return Collections.emptyList(); } //有缓存直接去缓存取 List<Advisor> advisors = new ArrayList<>(); for (String aspectName : aspectNames) { List<Advisor> cachedAdvisors = this.advisorsCache.get(aspectName); if (cachedAdvisors != null) { advisors.addAll(cachedAdvisors); } else { MetadataAwareAspectInstanceFactory factory = this.aspectFactoryCache.get(aspectName); advisors.addAll(this.advisorFactory.getAdvisors(factory)); } } return advisors; }
List<Advisor> classAdvisors = this.advisorFactory.getAdvisors(factory);获取aspecj的advisor并排序
/* org.springframework.aop.aspectj.annotation.ReflectiveAspectJAdvisorFactory#getAdvisors */ public List<Advisor> getAdvisors(MetadataAwareAspectInstanceFactory aspectInstanceFactory) { //获取aspectClass & AspectName并在此校验 Class<?> aspectClass = aspectInstanceFactory.getAspectMetadata().getAspectClass(); String aspectName = aspectInstanceFactory.getAspectMetadata().getAspectName(); validate(aspectClass); // We need to wrap the MetadataAwareAspectInstanceFactory with a decorator // so that it will only instantiate once. MetadataAwareAspectInstanceFactory lazySingletonAspectInstanceFactory = new LazySingletonAspectInstanceFactoryDecorator(aspectInstanceFactory); List<Advisor> advisors = new ArrayList<>(); //getAdvisorMethods获取aspect中advice方法并且排序， for (Method method : getAdvisorMethods(aspectClass)) { //注意advisors.size()这个参数，这里生成advisor实例类型是InstantiationModelAwarePointcutAdvisorImpl这个类实现了Ordered接口，
//advisors.size(）就是优先级，后面会根据这个变量排序一次 Advisor advisor = getAdvisor(method, lazySingletonAspectInstanceFactory, advisors.size(), aspectName); if (advisor != null) { advisors.add(advisor); } } // If it's a per target aspect, emit the dummy instantiating aspect. if (!advisors.isEmpty() && lazySingletonAspectInstanceFactory.getAspectMetadata().isLazilyInstantiated()) { Advisor instantiationAdvisor = new SyntheticInstantiationAdvisor(lazySingletonAspectInstanceFactory); advisors.add(0, instantiationAdvisor); } // Find introduction fields. //introduction：获取被@DeclareParents注解变量 for (Field field : aspectClass.getDeclaredFields()) { Advisor advisor = getDeclareParentsAdvisor(field); if (advisor != null) { advisors.add(advisor); } } return advisors; } private List<Method> getAdvisorMethods(Class<?> aspectClass) { final List<Method> methods = new ArrayList<>(); ReflectionUtils.doWithMethods(aspectClass, method -> { // Exclude pointcuts if (AnnotationUtils.getAnnotation(method, Pointcut.class) == null) { //获取aspect中的advice方法，没有被@Pointcut注解的方法,下面比较器中 //如果未被advice相关注解的方法，会设置为null，即排序的时候再筛选了一次 methods.add(method); } }, ReflectionUtils.USER_DECLARED_METHODS); // methods.sort(METHOD_COMPARATOR); return methods; }
METHOD_COMPARATOR:排序比较器
/* org.springframework.aop.aspectj.annotation.ReflectiveAspectJAdvisorFactory */ static { Comparator<Method> adviceKindComparator = new ConvertingComparator<>( //advice排序：around>before>after>afterReturning>afterThrowing
//后面还会调整：afterThrowing>afterReturning>after>around>before //运行无异常时：around before>before>around after>after>after returning> //有异常时：around before>before>after>afterThrowing new InstanceComparator<>( Around.class, Before.class, After.class, AfterReturning.class, AfterThrowing.class), (Converter<Method, Annotation>) method -> { AspectJAnnotation<?> annotation = AbstractAspectJAdvisorFactory.findAspectJAnnotationOnMethod(method); return (annotation != null ? annotation.getAnnotation() : null); }); Comparator<Method> methodNameComparator = new ConvertingComparator<>(Method::getName); METHOD_COMPARATOR = adviceKindComparator.thenComparing(methodNameComparator); }
Object proxy = createProxy(
bean.getClass(), beanName, specificInterceptors, new SingletonTargetSource(bean));创建代理对象proxy object
/* org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#createProxy */ protected Object createProxy(Class<?> beanClass, @Nullable String beanName, @Nullable Object[] specificInterceptors, TargetSource targetSource) { if (this.beanFactory instanceof ConfigurableListableBeanFactory) { //修改beandefinition.setAttribute(org.springframework.aop.framework.autoproxy.AutoProxyUtils.originalTargetClass,targetClass) AutoProxyUtils.exposeTargetClass((ConfigurableListableBeanFactory) this.beanFactory, beanName, beanClass); } ProxyFactory proxyFactory = new ProxyFactory(); proxyFactory.copyFrom(this); //传说中的ProxyTargetClass属性 //false 默认JDK动态代理、无接口类使用CgLib代理 //true 强制全部使用CgLib代理 if (!proxyFactory.isProxyTargetClass()) { if (shouldProxyTargetClass(beanClass, beanName)) { //beandefinition.getAttribute(org.springframework.aop.framework.autoproxy.AutoProxyUtils.preserveTargetClass) //=true,则使用Cglib代理 proxyFactory.setProxyTargetClass(true); } else { //检测beanClass如果实现了接口，记录所有的接口到proxyFactory.interfaces容器中 //检测beanClass如果没有实现接口 proxyFactory.setProxyTargetClass(true); evaluateProxyInterfaces(beanClass, proxyFactory); } } //将Advisor中实例转化为DefaultPointcutAdvisor实例 Advisor[] advisors = buildAdvisors(beanName, specificInterceptors); //设置advisors到proxyFactory proxyFactory.addAdvisors(advisors); //设置targetSource到proxyFactory proxyFactory.setTargetSource(targetSource); //空方法 customizeProxyFactory(proxyFactory); proxyFactory.setFrozen(this.freezeProxy); if (advisorsPreFiltered()) { proxyFactory.setPreFiltered(true); } //getProxyClassLoader 上下文线程类加载器，服务提供接口SPI了解一下 return proxyFactory.getProxy(getProxyClassLoader()); }
return proxyFactory.getProxy(getProxyClassLoader());创建Proxy object ==>createAopProxy().getProxy(classLoader);
//众所众知的默认代理设置 /*org.springframework.aop.framework.DefaultAopProxyFactory#createAopProxy */ public AopProxy createAopProxy(AdvisedSupport config) throws AopConfigException { if (config.isOptimize() || config.isProxyTargetClass() || hasNoUserSuppliedProxyInterfaces(config)) { //optimize = true //proxyTargetCass = true //proxyFactory.interfaces.length = 0 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() || Proxy.isProxyClass(targetClass)) { //目标类型是接口类型 || targetClass是Proxy的实现类 //返回JDK动态代理 return new JdkDynamicAopProxy(config); } //保底CgLib代理 return new ObjenesisCglibAopProxy(config); } else { //默认JDK动态代理 return new JdkDynamicAopProxy(config); } } /* org.springframework.aop.framework.JdkDynamicAopProxy#getProxy(java.lang.ClassLoader) */ public Object getProxy(@Nullable ClassLoader classLoader) { if (logger.isTraceEnabled()) { logger.trace("Creating JDK dynamic proxy: " + this.advised.getTargetSource()); } //proxy object需要实现的接口 Class<?>[] proxiedInterfaces = AopProxyUtils.completeProxiedInterfaces(this.advised, true); findDefinedEqualsAndHashCodeMethods(proxiedInterfaces); //动态代理InvocationHandler的那个类this=JdkDynamicAopProxy实例 return Proxy.newProxyInstance(classLoader, proxiedInterfaces, this); }
proxy.method == JdkDynamicAopProxy.invoke(method) == CglibAopProxy.DynamicAdvisedInterceptor.intercept(method):
具体实现逻辑很相似，仅仅是代理对象创建方式不同，方法调用的逻辑基本一致。
/* org.springframework.aop.framework.JdkDynamicAopProxy#invoke */ public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { ... // 生成一个advisor链，这里责任链模式Get the interception chain for this method // 验证当前方法是join point：pointAdvisor.getPointcut().getMethodMatcher().matchs(method) List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass); ... MethodInvocation invocation = new ReflectiveMethodInvocation(proxy, target, method, args, targetClass, chain); // Proceed to the joinpoint through the interceptor chain. //通过责任链顺序执行方法 retVal = invocation.proceed(); ... }
两种代理方法责任链模式实现是同一个方法。
/* org.springframework.aop.framework.ReflectiveMethodInvocation#proceed */ public Object proceed() throws Throwable { // We start with an index of -1 and increment early. if (this.currentInterceptorIndex == this.interceptorsAndDynamicMethodMatchers.size() - 1) { return invokeJoinpoint(); } 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. return ((MethodInterceptor) interceptorOrInterceptionAdvice).invoke(this); } }
具体流程
1、ExposeInvocationInterceptor----默认Advisor public Object invoke(MethodInvocation mi) throws Throwable { MethodInvocation oldInvocation = invocation.get(); invocation.set(mi); try { return mi.proceed(); } finally { invocation.set(oldInvocation); } } ----------- mi.proceed(); 2、AspectJAfterThrowingAdvice----AfterThrowingAdvice public Object invoke(MethodInvocation mi) throws Throwable { try { return mi.proceed(); } catch (Throwable ex) { if (shouldInvokeOnThrowing(ex)) { invokeAdviceMethod(getJoinPointMatch(), null, ex); } throw ex; } } ----------- try{ mi.proceed(); }catch(Throwable ex){ AfterThrowingAdvice } 3、AfterReturningAdviceInterceptor----AfterReturningAdvice public Object invoke(MethodInvocation mi) throws Throwable { Object retVal = mi.proceed(); this.advice.afterReturning(retVal, mi.getMethod(), mi.getArguments(), mi.getThis()); return retVal; } ------------- try{ mi.proceed(); AfterReturningAdvice }catch(Throwable ex){ AfterThrowingAdvice } 4、AspectJAfterAdvice----AfterAdvice public Object invoke(MethodInvocation mi) throws Throwable { try { return mi.proceed(); } finally { invokeAdviceMethod(getJoinPointMatch(), null, null); } } ---------------- try{ mi.proceed(); AfterReturningAdvice }catch(Throwable ex){ AfterThrowingAdvice }finally{ AfterAdvice } 5、AspectJAroundAdvice----AroundAdvice public Object invoke(MethodInvocation mi) throws Throwable { if (!(mi instanceof ProxyMethodInvocation)) { throw new IllegalStateException("MethodInvocation is not a Spring ProxyMethodInvocation: " + mi); } ProxyMethodInvocation pmi = (ProxyMethodInvocation) mi; ProceedingJoinPoint pjp = lazyGetProceedingJoinPoint(pmi); JoinPointMatch jpm = getJoinPointMatch(pmi); return invokeAdviceMethod(pjp, jpm, null, null); } ---------------- try{ around before advice mi.proceed(); around after advice AfterReturningAdvice }catch(Throwable ex){ AfterThrowingAdvice }finally{ AfterAdvice } 6、MethodBeforeAdviceInterceptor----BeforeAdvice public Object invoke(MethodInvocation mi) throws Throwable { this.advice.before(mi.getMethod(), mi.getArguments(), mi.getThis()); return mi.proceed(); } ----------------- try{ around after advice BeforeAdvice mi.proceed();//method.invoke(target,methodName); around after advice AfterReturningAdvice }catch(Throwable ex){ AfterThrowingAdvice }finally{ AfterAdvice }
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