目錄

AbstractAspectJAdvisorFactory

AspectJAnnotation?

ReflectiveAspectJAdvisorFactory

getAdvisors

getAdvisor

?getPointcut

getAdvice

InstantiationModelAwarePointcutAdvisorImpl

ProxyFactory

TargetClassAware?

ProxyConfig?

Advised

AdvisedSupport

?AdvisorChainFactory

DefaultAdvisorChainFactory?

ProxyCreatorSupport

ProxyFactory實現

AopProxyFactory?

?DefaultAopProxyFactory

AopProxy

JdkDynamicAopProxy

?ReflectiveMethodInvocation

ObjenesisCglibAopProxy?

Proxy

---

上篇文章提到Advisor由AspectJAdvisorFactory 的具體實現類ReflectiveAspectJAdvisorFactory真正創建。然后由ProxyFactory使用Advisors實現代理對象的創建。

?

AbstractAspectJAdvisorFactory

AbstractAspectJAdvisorFactory主要提供了一些通用方法。主要主要涉及的AspectJ注解包括：

private static final Class<?>[] ASPECTJ_ANNOTATION_CLASSES = new Class<?>[] {Pointcut.class, Around.class, Before.class, After.class, AfterReturning.class, AfterThrowing.class};

判斷是否有@Aspect注解。

@Overridepublic boolean isAspect(Class<?> clazz) {return (hasAspectAnnotation(clazz) && !compiledByAjc(clazz));}private boolean hasAspectAnnotation(Class<?> clazz) {return (AnnotationUtils.findAnnotation(clazz, Aspect.class) != null);}

?通過AnnotationUtils獲取注解信息。

protected static AspectJAnnotation<?> findAspectJAnnotationOnMethod(Method method) {for (Class<?> clazz : ASPECTJ_ANNOTATION_CLASSES) {AspectJAnnotation<?> foundAnnotation = findAnnotation(method, (Class<Annotation>) clazz);if (foundAnnotation != null) {return foundAnnotation;}}return null;}@Nullableprivate static <A extends Annotation> AspectJAnnotation<A> findAnnotation(Method method, Class<A> toLookFor) {A result = AnnotationUtils.findAnnotation(method, toLookFor);if (result != null) {return new AspectJAnnotation<>(result);}else {return null;}}

AspectJAnnotation?

AspectJAnnotation為AspectJ注解的包裝類。

//是什么注解 private final A annotation; //注解枚舉值 private final AspectJAnnotationType annotationType; //注解表達式 private final String pointcutExpression; //參數名稱 private final String argumentNames;static {annotationTypeMap.put(Pointcut.class, AspectJAnnotationType.AtPointcut);annotationTypeMap.put(Around.class, AspectJAnnotationType.AtAround);annotationTypeMap.put(Before.class, AspectJAnnotationType.AtBefore);annotationTypeMap.put(After.class, AspectJAnnotationType.AtAfter);annotationTypeMap.put(AfterReturning.class, AspectJAnnotationType.AtAfterReturning);annotationTypeMap.put(AfterThrowing.class, AspectJAnnotationType.AtAfterThrowing);}

ReflectiveAspectJAdvisorFactory

getAdvisors

?getAdvisors函數會獲取@Aspect修飾的實例中所有沒有被@Pointcut修飾的方法，然后調用getAdvisor函數，并且將這些方法作為參數。

@Overridepublic List<Advisor> getAdvisors(MetadataAwareAspectInstanceFactory aspectInstanceFactory) {//獲取Aspect類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<>();//獲取被@AspectJ注釋的所有方法。for (Method method : getAdvisorMethods(aspectClass)) {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.for (Field field : aspectClass.getDeclaredFields()) {Advisor advisor = getDeclareParentsAdvisor(field);if (advisor != null) {advisors.add(advisor);}}return advisors;}

?沒有被@PointCut注解的，則返回。

private List<Method> getAdvisorMethods(Class<?> aspectClass) {final List<Method> methods = new ArrayList<>();ReflectionUtils.doWithMethods(aspectClass, method -> {// Exclude pointcutsif (AnnotationUtils.getAnnotation(method, Pointcut.class) == null) {methods.add(method);}}, ReflectionUtils.USER_DECLARED_METHODS);methods.sort(METHOD_COMPARATOR);return methods;}

?

getAdvisor

生成Advisor，實際指：InstantiationModelAwarePointcutAdvisorImpl。

PointcutAdvisor實例中必然有一個Pointcut和Advice實例。修飾在方法上的注解包括：@Pointcut, @Around, @Before, @After, @AfterReturning和@AfterThrowing，所以InstantiationModelAwarePointcutAdvisorImpl會依據不同的不同的注解生成不同的Advice通知。

public Advisor getAdvisor(Method candidateAdviceMethod, MetadataAwareAspectInstanceFactory aspectInstanceFactory,int declarationOrderInAspect, String aspectName) { //判斷是否一個合法的AspectJ 類validate(aspectInstanceFactory.getAspectMetadata().getAspectClass()); // 獲得該方法上的切入點條件表達式AspectJExpressionPointcut expressionPointcut = getPointcut(candidateAdviceMethod, aspectInstanceFactory.getAspectMetadata().getAspectClass());if (expressionPointcut == null) {return null;} //return new InstantiationModelAwarePointcutAdvisorImpl(expressionPointcut, candidateAdviceMethod,this, aspectInstanceFactory, declarationOrderInAspect, aspectName);}

?getPointcut

獲取切入點表達式。

@Nullableprivate AspectJExpressionPointcut getPointcut(Method candidateAdviceMethod, Class<?> candidateAspectClass) { // 獲得該函數上@Pointcut, @Around, @Before, @After, @AfterReturning, @AfterThrowing注解的信息AspectJAnnotation<?> aspectJAnnotation =AbstractAspectJAdvisorFactory.findAspectJAnnotationOnMethod(candidateAdviceMethod);if (aspectJAnnotation == null) {return null;}AspectJExpressionPointcut ajexp =new AspectJExpressionPointcut(candidateAspectClass, new String[0], new Class<?>[0]); // 獲得注解信息中的切入點判斷表達式 ajexp.setExpression(aspectJAnnotation.getPointcutExpression());if (this.beanFactory != null) {ajexp.setBeanFactory(this.beanFactory);}return ajexp;}

getAdvice

為AspectJ方法構造Advice。根據不同的Aspect注解生成不同的Advice。

public Advice getAdvice(Method candidateAdviceMethod, AspectJExpressionPointcut expressionPointcut,MetadataAwareAspectInstanceFactory aspectInstanceFactory, int declarationOrder, String aspectName) {Class<?> candidateAspectClass = aspectInstanceFactory.getAspectMetadata().getAspectClass();validate(candidateAspectClass);//獲取方法上的AspectJ注解。AspectJAnnotation<?> aspectJAnnotation =AbstractAspectJAdvisorFactory.findAspectJAnnotationOnMethod(candidateAdviceMethod);if (aspectJAnnotation == null) {return null;}//走到此處，說明是個AspectJ方法，判斷是@AspectJ注解的if (!isAspect(candidateAspectClass)) {//異常}AbstractAspectJAdvice springAdvice;//根據注解類型生成Advice。switch (aspectJAnnotation.getAnnotationType()) {case AtPointcut:return null;case AtAround:springAdvice = new AspectJAroundAdvice(candidateAdviceMethod, expressionPointcut, aspectInstanceFactory);break;case AtBefore:springAdvice = new AspectJMethodBeforeAdvice(candidateAdviceMethod, expressionPointcut, aspectInstanceFactory);break;case AtAfter:springAdvice = new AspectJAfterAdvice(candidateAdviceMethod, expressionPointcut, aspectInstanceFactory);break;case AtAfterReturning:springAdvice = new AspectJAfterReturningAdvice(candidateAdviceMethod, expressionPointcut, aspectInstanceFactory);AfterReturning afterReturningAnnotation = (AfterReturning) aspectJAnnotation.getAnnotation();if (StringUtils.hasText(afterReturningAnnotation.returning())) {springAdvice.setReturningName(afterReturningAnnotation.returning());}break;case AtAfterThrowing:springAdvice = new AspectJAfterThrowingAdvice(candidateAdviceMethod, expressionPointcut, aspectInstanceFactory);AfterThrowing afterThrowingAnnotation = (AfterThrowing) aspectJAnnotation.getAnnotation();if (StringUtils.hasText(afterThrowingAnnotation.throwing())) {springAdvice.setThrowingName(afterThrowingAnnotation.throwing());}break;default:throw new UnsupportedOperationException("Unsupported advice type on method: " + candidateAdviceMethod);}// 配置Advice。springAdvice.setAspectName(aspectName);springAdvice.setDeclarationOrder(declarationOrder);String[] argNames = this.parameterNameDiscoverer.getParameterNames(candidateAdviceMethod);if (argNames != null) {springAdvice.setArgumentNamesFromStringArray(argNames);}springAdvice.calculateArgumentBindings();return springAdvice;}

InstantiationModelAwarePointcutAdvisorImpl

InstantiationModelAwarePointcutAdvisorImpl的繼承結構如下圖，它本身是個Advisor，并且是個PointcutAdvisor。是對各種AspectJ 增強的封裝。

它包括以下屬性：

private static final Advice EMPTY_ADVICE = new Advice() {};private final AspectJExpressionPointcut declaredPointcut; //定義類型private final Class<?> declaringClass; //方法名private final String methodName; //參數類型private final Class<?>[] parameterTypes; //AspectJ方法private transient Method aspectJAdviceMethod;private final AspectJAdvisorFactory aspectJAdvisorFactory;private final MetadataAwareAspectInstanceFactory aspectInstanceFactory; //順序private final int declarationOrder; //AspectJ名稱private final String aspectName; //切點private final Pointcut pointcut; //private final boolean lazy; //Advice@Nullableprivate Advice instantiatedAdvice;@Nullableprivate Boolean isBeforeAdvice;@Nullableprivate Boolean isAfterAdvice;

在構造函數中，會根據參數生成Advice。調用的aspectJAdvisorFactory的getAdvice方法。見前面內容。

private Advice instantiateAdvice(AspectJExpressionPointcut pointcut) {Advice advice = this.aspectJAdvisorFactory.getAdvice(this.aspectJAdviceMethod, pointcut,this.aspectInstanceFactory, this.declarationOrder, this.aspectName);return (advice != null ? advice : EMPTY_ADVICE);}

ProxyFactory

ProxyFactory是真正創建代理對象的類，其類繼承結構如下圖：

TargetClassAware?

public interface TargetClassAware {/**代理實現后面的目標類類型，可能是一個proxy，也可能是代理配置。*/@NullableClass<?> getTargetClass();}

ProxyConfig?

上篇已介紹，主要是代理配置信息。

Advised

封裝代理配置信息的接口，配置包含：Interceptors 、other advice、 Advisors、proxied interfaces。

public interface Advised extends TargetClassAware {boolean isFrozen();/**是否代理的target class，而不是特定接口* Are we proxying the full target class instead of specified interfaces?*/boolean isProxyTargetClass();Class<?>[] getProxiedInterfaces();boolean isInterfaceProxied(Class<?> intf);void setTargetSource(TargetSource targetSource);TargetSource getTargetSource();void setExposeProxy(boolean exposeProxy);boolean isExposeProxy();void setPreFiltered(boolean preFiltered);boolean isPreFiltered();/*Advisor相關*/Advisor[] getAdvisors();void addAdvisor(Advisor advisor) throws AopConfigException;void addAdvisor(int pos, Advisor advisor) throws AopConfigException;boolean removeAdvisor(Advisor advisor);void removeAdvisor(int index) throws AopConfigException;int indexOf(Advisor advisor);boolean replaceAdvisor(Advisor a, Advisor b) throws AopConfigException;/*Advice相關*/void addAdvice(Advice advice) throws AopConfigException;void addAdvice(int pos, Advice advice) throws AopConfigException;boolean removeAdvice(Advice advice);int indexOf(Advice advice);String toProxyConfigString(); }

AdvisedSupport

Advised的一個具體實現，就是怎么存、取屬性值。引入了AdvisorChainFactory 。

AdvisorChainFactory advisorChainFactory = new DefaultAdvisorChainFactory();

?AdvisorChainFactory

AdvisorChainFactory主要實現Advisor鏈。為指定方法構造Advisor鏈。默認實現為：DefaultAdvisorChainFactory。

public interface AdvisorChainFactory {List<Object> getInterceptorsAndDynamicInterceptionAdvice(Advised config, Method method, @Nullable Class<?> targetClass);}

DefaultAdvisorChainFactory?

返回方法的所有Advisor，根據Advisor類型來決定是否匹配方法。

@Overridepublic List<Object> getInterceptorsAndDynamicInterceptionAdvice(Advised config, Method method, @Nullable Class<?> targetClass) {AdvisorAdapterRegistry registry = GlobalAdvisorAdapterRegistry.getInstance();//獲取所有Advisor。Advisor[] advisors = config.getAdvisors();List<Object> interceptorList = new ArrayList<>(advisors.length);//目標類實際類型。Class<?> actualClass = (targetClass != null ? targetClass : method.getDeclaringClass());Boolean hasIntroductions = null;//循環每個Advisor。for (Advisor advisor : advisors) {//切點類型Advisor。if (advisor instanceof PointcutAdvisor) {PointcutAdvisor pointcutAdvisor = (PointcutAdvisor) advisor;//類類型是否匹配。if (config.isPreFiltered() || pointcutAdvisor.getPointcut().getClassFilter().matches(actualClass)) {MethodMatcher mm = pointcutAdvisor.getPointcut().getMethodMatcher();boolean match;if (mm instanceof IntroductionAwareMethodMatcher) {if (hasIntroductions == null) {hasIntroductions = hasMatchingIntroductions(advisors, actualClass);}match = ((IntroductionAwareMethodMatcher) mm).matches(method, actualClass, hasIntroductions);}else {match = mm.matches(method, actualClass);}//方法是否匹配if (match) {MethodInterceptor[] interceptors = registry.getInterceptors(advisor);//動態匹配。if (mm.isRuntime()) {for (MethodInterceptor interceptor : interceptors) {interceptorList.add(new InterceptorAndDynamicMethodMatcher(interceptor, mm));}}else {//靜態匹配。interceptorList.addAll(Arrays.asList(interceptors));}}}}//引介類型Advisor。else if (advisor instanceof IntroductionAdvisor) {IntroductionAdvisor ia = (IntroductionAdvisor) advisor;//引介類型 僅需要匹配 類類型。if (config.isPreFiltered() || ia.getClassFilter().matches(actualClass)) {Interceptor[] interceptors = registry.getInterceptors(advisor);interceptorList.addAll(Arrays.asList(interceptors));}}//其他Advisor，默認表示匹配。else {Interceptor[] interceptors = registry.getInterceptors(advisor);interceptorList.addAll(Arrays.asList(interceptors));}}return interceptorList;}

ProxyCreatorSupport

代理工廠的實現的基本支持類，引入了AopProxyFactory （DefaultAopProxyFactory）。并且通過AopProxyFactory.createAopProxy()創建AopProxy實例。

private AopProxyFactory aopProxyFactory;public ProxyCreatorSupport() {this.aopProxyFactory = new DefaultAopProxyFactory();} protected final synchronized AopProxy createAopProxy() {if (!this.active) {activate();}return getAopProxyFactory().createAopProxy(this);}

ProxyFactory實現

ProxyFactory主要提供了些操作Advised屬性的方法，例如增加接口，設置TargetSource等，內部調用AopProxy.getProxy()方法生成代理實例。

AopProxyFactory?

根據代理配置信息，生成Aop代理。

public interface AopProxyFactory {AopProxy createAopProxy(AdvisedSupport config) throws AopConfigException;}

?DefaultAopProxyFactory

根據代理配置信息，決定是使用JDK動態代理，還是cglib代理。

@Overridepublic 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() || Proxy.isProxyClass(targetClass)) {return new JdkDynamicAopProxy(config);}return new ObjenesisCglibAopProxy(config);}else {return new JdkDynamicAopProxy(config);}}

AopProxy

AopProxy是真正產生代理實例的類。包括JDK動態代理實現和cglib實現。

public interface AopProxy {Object getProxy();Object getProxy(@Nullable ClassLoader classLoader);}

JdkDynamicAopProxy

JdkDynamicAopProxy又實現了InvocationHandler接口，使用java.lang.reflect.Proxy 通過反射來構造實例。JdkDynamicAopProxy的invoke方法中，如果有Advisor，則會生成一個ReflectiveMethodInvocation對象，執行增強。

@Overridepublic Object getProxy(@Nullable ClassLoader classLoader) {if (logger.isTraceEnabled()) {logger.trace("Creating JDK dynamic proxy: " + this.advised.getTargetSource());}Class<?>[] proxiedInterfaces = AopProxyUtils.completeProxiedInterfaces(this.advised, true);findDefinedEqualsAndHashCodeMethods(proxiedInterfaces);return Proxy.newProxyInstance(classLoader, proxiedInterfaces, this);} @Override@Nullablepublic Object invoke(Object proxy, Method method, Object[] args) throws Throwable {Object oldProxy = null;boolean setProxyContext = false;TargetSource targetSource = this.advised.targetSource;Object target = null;try {//target自身沒有實現equal方法，if (!this.equalsDefined && AopUtils.isEqualsMethod(method)) {return equals(args[0]);}//target自身沒有實現hashCode方法，else if (!this.hashCodeDefined && AopUtils.isHashCodeMethod(method)) {return hashCode();}else if (method.getDeclaringClass() == DecoratingProxy.class) {// There is only getDecoratedClass() declared -> dispatch to proxy config.return AopProxyUtils.ultimateTargetClass(this.advised);}else if (!this.advised.opaque && method.getDeclaringClass().isInterface() &&method.getDeclaringClass().isAssignableFrom(Advised.class)) {// Service invocations on ProxyConfig with the proxy config...return AopUtils.invokeJoinpointUsingReflection(this.advised, method, args);}Object retVal;if (this.advised.exposeProxy) {// Make invocation available if necessary.oldProxy = AopContext.setCurrentProxy(proxy);setProxyContext = true;}//獲取最后一個Target，targetSource的target會變化。target = targetSource.getTarget();Class<?> targetClass = (target != null ? target.getClass() : null);//獲取方法的攔截器鏈。List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);//如果沒有任何advice，直接調用 target的方法。if (chain.isEmpty()) {Object[] argsToUse = AopProxyUtils.adaptArgumentsIfNecessary(method, args);retVal = AopUtils.invokeJoinpointUsingReflection(target, method, argsToUse);}else {如果有advice，則構造MethodInvocation，調用proceed。MethodInvocation invocation =new ReflectiveMethodInvocation(proxy, target, method, args, targetClass, chain);retVal = invocation.proceed();}// Massage return value if necessary.Class<?> returnType = method.getReturnType();if (retVal != null && retVal == target &&returnType != Object.class && returnType.isInstance(proxy) &&!RawTargetAccess.class.isAssignableFrom(method.getDeclaringClass())) {//如果方法返回結果為this，則返回proxy。retVal = proxy;}else if (retVal == null && returnType != Void.TYPE && returnType.isPrimitive()) {throw new AopInvocationException("Null return value from advice does not match primitive return type for: " + method);}return retVal;}finally {if (target != null && !targetSource.isStatic()) {// 如果可能釋放target。targetSource.releaseTarget(target);}if (setProxyContext) {// Restore old proxy.AopContext.setCurrentProxy(oldProxy);}}}

?ReflectiveMethodInvocation

屬性：

protected ReflectiveMethodInvocation(Object proxy, @Nullable Object target, Method method, @Nullable Object[] arguments,@Nullable Class<?> targetClass, List<Object> interceptorsAndDynamicMethodMatchers) {this.proxy = proxy;this.target = target;this.targetClass = targetClass;this.method = BridgeMethodResolver.findBridgedMethod(method);this.arguments = AopProxyUtils.adaptArgumentsIfNecessary(method, arguments);this.interceptorsAndDynamicMethodMatchers = interceptorsAndDynamicMethodMatchers;}

proceed

?

@Override@Nullablepublic Object proceed() throws Throwable {// 最后一個攔截器，則調用invokeJoinpoint，使用代理的方法。if (this.currentInterceptorIndex == this.interceptorsAndDynamicMethodMatchers.size() - 1) {return invokeJoinpoint();}//循環攔截器。Object interceptorOrInterceptionAdvice =this.interceptorsAndDynamicMethodMatchers.get(++this.currentInterceptorIndex);//動態攔截器if (interceptorOrInterceptionAdvice instanceof InterceptorAndDynamicMethodMatcher) {InterceptorAndDynamicMethodMatcher dm =(InterceptorAndDynamicMethodMatcher) interceptorOrInterceptionAdvice;Class<?> targetClass = (this.targetClass != null ? this.targetClass : this.method.getDeclaringClass());//匹配，則返回攔截器的調用。if (dm.methodMatcher.matches(this.method, targetClass, this.arguments)) {return dm.interceptor.invoke(this);}else {//不匹配，則下一個。return proceed();}}else {//靜態攔截器，直接調用增強方法。return ((MethodInterceptor) interceptorOrInterceptionAdvice).invoke(this);}}

ObjenesisCglibAopProxy?

不細談，具體的了解cglib相關知識。

Proxy

Proxy是反射包中的實現類。主要方法是newProxyInstance。

public static Object newProxyInstance(ClassLoader loader,Class<?>[] interfaces,InvocationHandler h)throws IllegalArgumentException{Objects.requireNonNull(h);final Class<?>[] intfs = interfaces.clone(); ... ... /** 調用native方法生成代理類.*/Class<?> cl = getProxyClass0(loader, intfs);try {if (sm != null) {checkNewProxyPermission(Reflection.getCallerClass(), cl);}//獲取代理類的構造函數。InvocationHandler.classfinal Constructor<?> cons = cl.getConstructor(constructorParams);... ... //實例化。return cons.newInstance(new Object[]{h});} catch (IllegalAccessException|InstantiationException e) {... ... }}

?

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