锐客网

  1. 首页 > it技术 > >

Spring|Spring AOP 的实现

在了解Spring AOP的实现之前，先了解一些Spring AOP的相关概念
AOP的相关概念 在使用Spring进行AOP相关的编程时，我们经常使用Advice (通知), PointCut (切点), Advisor (通知器)来实现我们需要的功能。
Advice
Advice是AOP联盟定义的一个接口，定义了我们可以在切点做些什么，即我们希望织入的增强逻辑，为切面增强提供织入的入口。在Spring中，Advice作为一个统一的接口，Spring在Advice的基础上定义了具体的通知类型，比如,

  • BeforeAdvice: 前置增强接口，在目标方法调用之前回调。
  • AfterAdvice : 后置增强接口，在目标方法调用结束并成功返回时回调。
  • ThrowAdvice : 在抛出异常时回调。
  • Interceptor: 表示一个通用的拦截器，可以在方法的调用前后进行增强。
  • DynamicIntroductionAdvice: 与上面的Advice和Interceptor不同，DynamicIntroductionAdvice不对方法进行增强，而是动态的引入新的接口实现。我们可以为目标类添加一个接口的实现（原来目标类未实现某个接口）,那么通过DynamicIntroductionAdvice增强可以为目标类创建实现某接口的代理。
Spring|Spring AOP 的实现
文章图片

Pointcut
Pointcut 决定Advice可以作用于哪些连接点，即通过Pointcut我们可以定义需要增强的方法的集合。这些方法的集合可以通过Pointcut中定义的规则来选取，当方法符合Pointcut定义的规则时，返回true。这些规则可是正则表达式，也可以是字符串的匹配等。
Spring定义了Pointcut的接口，Pointcut接口中定义了用于获取类过滤器和方法匹配器的抽象方法。
public interface Pointcut {/** * Return the ClassFilter for this pointcut. * @return the ClassFilter (never {@code null}) */ ClassFilter getClassFilter(); /** * Return the MethodMatcher for this pointcut. * @return the MethodMatcher (never {@code null}) */ MethodMatcher getMethodMatcher(); /** * Canonical Pointcut instance that always matches. */ Pointcut TRUE = TruePointcut.INSTANCE; }

但是有了类过滤器和方法匹配器，我们还需要知道如何使用类过滤器和方法匹配器，因此在实现Pointcut的同时也需要实现MethodMatcher。MethodMatcher定义了matches方法，即用于规则匹配的方法。
public interface MethodMatcher {/** * Perform static checking whether the given method matches. * If this returns {@code false} or if the {@link #isRuntime()} * method returns {@code false}, no runtime check (i.e. no * {@link #matches(java.lang.reflect.Method, Class, Object[])} call) * will be made. * @param method the candidate method * @param targetClass the target class * @return whether or not this method matches statically */ boolean matches(Method method, Class targetClass); /** * Is this MethodMatcher dynamic, that is, must a final call be made on the * {@link #matches(java.lang.reflect.Method, Class, Object[])} method at * runtime even if the 2-arg matches method returns {@code true}? * Can be invoked when an AOP proxy is created, and need not be invoked * again before each method invocation, * @return whether or not a runtime match via the 3-arg * {@link #matches(java.lang.reflect.Method, Class, Object[])} method * is required if static matching passed */ boolean isRuntime(); /** * Check whether there a runtime (dynamic) match for this method, * which must have matched statically. * This method is invoked only if the 2-arg matches method returns * {@code true} for the given method and target class, and if the * {@link #isRuntime()} method returns {@code true}. Invoked * immediately before potential running of the advice, after any * advice earlier in the advice chain has run. * @param method the candidate method * @param targetClass the target class * @param args arguments to the method * @return whether there's a runtime match * @see MethodMatcher#matches(Method, Class) */ boolean matches(Method method, Class targetClass, Object... args); /** * Canonical instance that matches all methods. */ MethodMatcher TRUE = TrueMethodMatcher.INSTANCE; }

下图给出了Spring中一些Pointcut的继承关系，可以看到具体的实现都集成了Pointcut接口和MethodMatcher接口。
Spring|Spring AOP 的实现
文章图片

Advisor
前面介绍了Advice的增强逻辑，Pointcut定义了方法的集合，但是哪些方法使用什么样的增强逻辑依旧没有关联起来，Advisor就是将Advice和Pointcut结合起来，通过Advisor，可以定义在某个Pointcut连接点上使用哪个Advice。
Spring 提供了一个DefaultPointcutAdvisor, 在DefaultPointcutAdvisor中有两个属性，分别为advice和pointcut用来配置Advice 和Pointcut。 其实现如下所示。
public class DefaultPointcutAdvisor extends AbstractGenericPointcutAdvisor implements Serializable {private Pointcut pointcut = Pointcut.TRUE; /** * Create an empty DefaultPointcutAdvisor. * Advice must be set before use using setter methods. * Pointcut will normally be set also, but defaults to {@code Pointcut.TRUE}. */ public DefaultPointcutAdvisor() { }/** * Create a DefaultPointcutAdvisor that matches all methods. * {@code Pointcut.TRUE} will be used as Pointcut. * @param advice the Advice to use */ public DefaultPointcutAdvisor(Advice advice) { this(Pointcut.TRUE, advice); }/** * Create a DefaultPointcutAdvisor, specifying Pointcut and Advice. * @param pointcut the Pointcut targeting the Advice * @param advice the Advice to run when Pointcut matches */ public DefaultPointcutAdvisor(Pointcut pointcut, Advice advice) { this.pointcut = pointcut; setAdvice(advice); }/** * Specify the pointcut targeting the advice. * Default is {@code Pointcut.TRUE}. * @see #setAdvice */ public void setPointcut(@Nullable Pointcut pointcut) { this.pointcut = (pointcut != null ? pointcut : Pointcut.TRUE); }@Override public Pointcut getPointcut() { return this.pointcut; }@Override public String toString() { return getClass().getName() + ": pointcut [" + getPointcut() + "]; advice [" + getAdvice() + "]"; }}

Spring AOP的实现 前面已经介绍了Spring AOP的相关概念，但是Spring AOP是如何对方法的调用进行拦截的呢？下面就Spring AOP的实现进行分析。
同样以Spring中的单元测试开始Spring AOP的实现分析。
通过以下代码开始Spring AOP的实现分析。
@Test public void testProxyFactory() { TestBean target = new TestBean(); ProxyFactory pf = new ProxyFactory(target); NopInterceptor nop = new NopInterceptor(); CountingBeforeAdvice cba = new CountingBeforeAdvice(); Advisor advisor = new DefaultPointcutAdvisor(cba); pf.addAdvice(nop); pf.addAdvisor(advisor); ITestBean proxied = (ITestBean) pf.getProxy(); proxied.setAge(5); assertThat(cba.getCalls()).isEqualTo(1); assertThat(nop.getCount()).isEqualTo(1); assertThat(pf.removeAdvisor(advisor)).isTrue(); assertThat(proxied.getAge()).isEqualTo(5); assertThat(cba.getCalls()).isEqualTo(1); assertThat(nop.getCount()).isEqualTo(2); }

上述的代码中创建了一个TestBean，NopInterceptor, CountingBeforeAdvice对象，并使用TestBean初始化了ProxyFactory，CountingBeforeAdvice对象初始化DefaultPointcutAdvisor，同时将NopInterceptorDefaultPointcutAdvisor添加到ProxyFactory中。可以看到上述的代码中没有指明Pointcut, 也就意味着使用了默认的Pointcut.TRUE, 即对所有的方法都进行增强。
首先来看一下ProxyFactory的继承关系。
Spring|Spring AOP 的实现
文章图片

从上往下看，首先是TargetClassAware, 定义了一个getTargetClass()方法用来获取目标对象的Class，Advised继承了该接口，Advised接口定义了获取和设置AOP 代理工厂(Aop proxy factory)配置的方法,具体代码如下：
public interface Advised extends TargetClassAware {boolean isFrozen(); 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[] getAdvisors(); default int getAdvisorCount() { return getAdvisors().length; }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; void addAdvice(Advice advice) throws AopConfigException; void addAdvice(int pos, Advice advice) throws AopConfigException; boolean removeAdvice(Advice advice); int indexOf(Advice advice); String toProxyConfigString(); }

而ProxyConfig则保存了AOP 代理工厂的部分属性，可以看成是一个数据基类，如下：
public class ProxyConfig implements Serializable { ... private boolean proxyTargetClass = false; private boolean optimize = false; boolean opaque = false; boolean exposeProxy = false; private boolean frozen = false; ... }

AdvisedSupport 继承了ProxyConfig同时实现了Advised接口，封装了AOP对Advice和Advisor的相关操作。
/** The AdvisorChainFactory to use. */ AdvisorChainFactory advisorChainFactory = new DefaultAdvisorChainFactory(); /** Cache with Method as key and advisor chain List as value. */ private transient Map> methodCache; /** * Interfaces to be implemented by the proxy. Held in List to keep the order * of registration, to create JDK proxy with specified order of interfaces. */ private List> interfaces = new ArrayList<>(); /** * List of Advisors. If an Advice is added, it will be wrapped * in an Advisor before being added to this List. */ private List advisors = new ArrayList<>();

ProxyCreatorSupport 则提供了设置ProxyFactory和创建代理对象的方法，创建的具体的代理对象则交给具体的ProxyFactory完成。
最下面的则是三个具体的ProxyFactory的实现，分别为：
  • ProxyFactory，可以在IOC容器中使用声明式配置AOP。
  • ProxyFactoryBean，需要编程式的使用AOP
  • AspectProxyFactory， 对于使用AspectJ的AOP应用，集成了Spring和AspectJ。
了解了ProxyFactory的继承关系后，继续往下看，我们已经知道了具体的代理的对象的创建交给具体的ProxyFactory。
我们主要关注下面用于获取代理对象的这行代码：
ITestBean proxied = (ITestBean) pf.getProxy();

ProxyFactory 的getProxy的实现如下：
public Object getProxy() { return createAopProxy().getProxy(); }

getProxy()调用ProxyCreatorSupport的createAopProxy()用于创建AopProxy。
protected final synchronized AopProxy createAopProxy() { if (!this.active) { activate(); } return getAopProxyFactory().createAopProxy(this); }

createAopProxy()先通过getAopProxyFactory()获取AopProxyFactory。getAopProxyFactory()直接返回一个DefaultAopProxyFactory的对象，然后调用DefaultAopProxyFactory的createAopProxy()方法创建具体的AopProxy，并传入this指针，即ProxyFactory对象本身，因为ProxyFactory继承了AdvisedSupport。
public AopProxy createAopProxy(AdvisedSupport config) throws AopConfigException { if (!NativeDetector.inNativeImage() && (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); } } private boolean hasNoUserSuppliedProxyInterfaces(AdvisedSupport config) { Class[] ifcs = config.getProxiedInterfaces(); return (ifcs.length == 0 || (ifcs.length == 1 && SpringProxy.class.isAssignableFrom(ifcs[0]))); }

  • config.isOptimize()：表示是否使用了优化策略，配置的属性optimize值决定；
  • config.isProxyTargetClass()：表示是否是代理目标类，配置的属性proxy-target-class值决定；
  • hasNoUserSuppliedProxyInterfaces()：就是在判断代理的对象是否有实现接口
当代理的是接口时，则使用JdkDynamicAopProxy，否则使用ObjenesisCglibAopProxy()。
JdkDynamicAopProxy保存了config和需要代理的接口。
public JdkDynamicAopProxy(AdvisedSupport config) throws AopConfigException { Assert.notNull(config, "AdvisedSupport must not be null"); if (config.getAdvisorCount() == 0 && config.getTargetSource() == AdvisedSupport.EMPTY_TARGET_SOURCE) { throw new AopConfigException("No advisors and no TargetSource specified"); } this.advised = config; this.proxiedInterfaces = AopProxyUtils.completeProxiedInterfaces(this.advised, true); findDefinedEqualsAndHashCodeMethods(this.proxiedInterfaces); }

当advised没有实现SpringProxy，Advised, DecoratingProxy 接口AopProxyUtils.completeProxiedInterfaces()会分别添加这三个接口。
到这里AopProxyFactory就实例化完成了。继续看getProxy()做了什么。
public Object getProxy() { return getProxy(ClassUtils.getDefaultClassLoader()); } public Object getProxy(@Nullable ClassLoader classLoader) { if (logger.isTraceEnabled()) { logger.trace("Creating JDK dynamic proxy: " + this.advised.getTargetSource()); } return Proxy.newProxyInstance(classLoader, this.proxiedInterfaces, this); }

通过将classLoader, proxiedInterfaces和this传入到newProxyInstance中去创建了目标对象的代理对象。JdkDynamicAopProxy实现了InvocationHandler接口，因此可以将this指针传进去创建代理对象。
代理对象创建完成之后，当我们调用代理对象的方法时，就会回调JdkDynamicAopProxy的invoke()方法。到这里我们只看见了代理对象的创建，依旧没有看到怎么对方法进行增强的逻辑，因为对代码进行增强的实现就在invoke()方法里面。
接下来看一下invoke()方法。
public 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 { if (!this.equalsDefined && AopUtils.isEqualsMethod(method)) { // The target does not implement the equals(Object) method itself. return equals(args[0]); } else if (!this.hashCodeDefined && AopUtils.isHashCodeMethod(method)) { // The target does not implement the hashCode() method itself. 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; }// 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); // Get the interception chain for this method. List chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass); // Check whether we have any advice. If we don't, we can fallback on direct // reflective invocation of the target, and avoid creating a MethodInvocation. if (chain.isEmpty()) { // 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 = AopUtils.invokeJoinpointUsingReflection(target, method, argsToUse); } else { // We need to create a method invocation... MethodInvocation invocation = new ReflectiveMethodInvocation(proxy, target, method, args, targetClass, chain); // Proceed to the joinpoint through the interceptor 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())) { // Special case: it returned "this" and the return type of the method // is type-compatible. Note that we can't help if the target sets // a reference to itself in another returned object. 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()) { // Must have come from TargetSource. targetSource.releaseTarget(target); } if (setProxyContext) { // Restore old proxy. AopContext.setCurrentProxy(oldProxy); } } }
invoke()的入参为代理对象，调用的方法，以及调用方法的参数。invoke()方首先检查method是不是equal，hashCode方法，以及declaringClass是不是DecoratingProxy，是不是需要将proxy设置到AopContext里面。做完这一系列的检查之后，通过getInterceptorsAndDynamicInterceptionAdvice(）获取Interceptor和Advice保存到chain中，如果chain为空，表示没有interceptor和Advice,则直接通过反射的方法调用目标方法，invokeJoinpointUsingReflection()方法封装反射调用的逻辑。如果非空，则构造一个ReflectiveMethodInvocation对象，ReflectiveMethodInvocation对象的proceed方法封装了Advice方法的增强逻辑。
先来看一下getInterceptorsAndDynamicInterceptionAdvice(）的实现：
public List getInterceptorsAndDynamicInterceptionAdvice(Method method, @Nullable Class targetClass) { MethodCacheKey cacheKey = new MethodCacheKey(method); List cached = this.methodCache.get(cacheKey); if (cached == null) { cached = this.advisorChainFactory.getInterceptorsAndDynamicInterceptionAdvice( this, method, targetClass); this.methodCache.put(cacheKey, cached); } return cached; }
先将method封装成MethodCacheKey，然后尝试从缓存中获取这个key对应的缓存，如果没有，则通过advisorChainFactory.getInterceptorsAndDynamicInterceptionAdvice(）去获取，这里的advisorChainFactory的默认实现是DefaultAdvisorChainFactory，看一下getInterceptorsAndDynamicInterceptionAdvice()的实现。
public List getInterceptorsAndDynamicInterceptionAdvice( Advised config, Method method, @Nullable Class targetClass) {// This is somewhat tricky... We have to process introductions first, // but we need to preserve order in the ultimate list. AdvisorAdapterRegistry registry = GlobalAdvisorAdapterRegistry.getInstance(); Advisor[] advisors = config.getAdvisors(); List interceptorList = new ArrayList<>(advisors.length); Class actualClass = (targetClass != null ? targetClass : method.getDeclaringClass()); Boolean hasIntroductions = null; for (Advisor advisor : advisors) { if (advisor instanceof PointcutAdvisor) { // Add it conditionally. PointcutAdvisor pointcutAdvisor = (PointcutAdvisor) advisor; 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); } if (match) { MethodInterceptor[] interceptors = registry.getInterceptors(advisor); if (mm.isRuntime()) { // Creating a new object instance in the getInterceptors() method // isn't a problem as we normally cache created chains. for (MethodInterceptor interceptor : interceptors) { interceptorList.add(new InterceptorAndDynamicMethodMatcher(interceptor, mm)); } } else { interceptorList.addAll(Arrays.asList(interceptors)); } } } } else if (advisor instanceof IntroductionAdvisor) { IntroductionAdvisor ia = (IntroductionAdvisor) advisor; if (config.isPreFiltered() || ia.getClassFilter().matches(actualClass)) { Interceptor[] interceptors = registry.getInterceptors(advisor); interceptorList.addAll(Arrays.asList(interceptors)); } } else { Interceptor[] interceptors = registry.getInterceptors(advisor); interceptorList.addAll(Arrays.asList(interceptors)); } }return interceptorList; }
上述的代码首先通过GlobalAdvisorAdapterRegistry.getInstance()获取了DefaultAdvisorAdapterRegistry的实例，DefaultAdvisorAdapterRegistry注册了三种Adviced的适配器，用于将Advice适配成Interceptor。
public DefaultAdvisorAdapterRegistry() { registerAdvisorAdapter(new MethodBeforeAdviceAdapter()); registerAdvisorAdapter(new AfterReturningAdviceAdapter()); registerAdvisorAdapter(new ThrowsAdviceAdapter()); }

然后对我们添加的Advisor逐个遍历，首先判断是不是PointcutAdvisor，然后判断是不是IntroductionAdvisor，如果都不是则认为是Interceptor。如果当前的advisor是PointcutAdvisor，则先判断是不是提前过滤过了，或者class是否符合ClassFilter中定义的规则，如果进一步判断MethodMatcher的类型以及method是否匹配。无论是PointcutAdvisor，IntroductionAdvisor还是Interceptor， 最后都通过 registry.getInterceptors()方法对advisor进行适配，将advisor对象通过响应的适配器适配成MethodInterceptor的一个实例。具体的实现如下所示：
public MethodInterceptor[] getInterceptors(Advisor advisor) throws UnknownAdviceTypeException { List interceptors = new ArrayList<>(3); Advice advice = advisor.getAdvice(); if (advice instanceof MethodInterceptor) { interceptors.add((MethodInterceptor) advice); } for (AdvisorAdapter adapter : this.adapters) { if (adapter.supportsAdvice(advice)) { interceptors.add(adapter.getInterceptor(advisor)); } } if (interceptors.isEmpty()) { throw new UnknownAdviceTypeException(advisor.getAdvice()); } return interceptors.toArray(new MethodInterceptor[0]); }

看一下其中一个adapter的实现。
class MethodBeforeAdviceAdapter implements AdvisorAdapter, Serializable {@Override public boolean supportsAdvice(Advice advice) { return (advice instanceof MethodBeforeAdvice); }@Override public MethodInterceptor getInterceptor(Advisor advisor) { MethodBeforeAdvice advice = (MethodBeforeAdvice) advisor.getAdvice(); return new MethodBeforeAdviceInterceptor(advice); }}public class MethodBeforeAdviceInterceptor implements MethodInterceptor, BeforeAdvice, Serializable {private final MethodBeforeAdvice advice; public MethodBeforeAdviceInterceptor(MethodBeforeAdvice advice) { Assert.notNull(advice, "Advice must not be null"); this.advice = advice; }@Override @Nullable public Object invoke(MethodInvocation mi) throws Throwable { this.advice.before(mi.getMethod(), mi.getArguments(), mi.getThis()); return mi.proceed(); }}

可以看到对于BeforeAdvice最终被是配成了MethodBeforeAdviceInterceptor，实现了MethodInterceptor接口，其中invoke方法就是后面拦截器链的入口。
继续看proceed的实现。
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); } }

从索引为-1开始递增，如果所有的Interceptor或者Advice都调用完毕，则通过反射调用目标函数。如果当前的interceptorOrInterceptionAdvice是InterceptorAndDynamicMethodMatcher的实例，则先通matches方法进行匹配，如果匹配成功，则调用interceptor的invoke方法，否则跳过，如果不是InterceptorAndDynamicMethodMatcher的实例则时表示是一个interceptor,也直接调用invoke方法。
结合上述的MethodInterceptor的invoke方法，可以看到所有的Advice和interceptor串成了一条拦截器链，从头开始，通过matches方法进行匹配，匹配成功则进行增强，否则继续往下查找，直到尾部，调用目标方法，整个过程就是对目标方法的增强过程，也是AOP的实现原理。
总结 【Spring|Spring AOP 的实现】本文以ProxyFactory为例分析了Spring AOP的实现，其实现原理大致可以分为三个部分：
  1. Advice, Pointcut,Advisor的实现
  2. 目标对象代理对象的生成。
  3. 对Advice进行适配，并组装成一条拦截器链，通过拦截器链对目标方法进行增强。

    推荐阅读


    上一篇：机器学习中常见的几种最优化方法

    下一篇：没有性能瓶颈的无限级菜单树应该这样设计