SpringAop 流程源码阅读

AOP的核心概念

由来

AOP是切面的意思，面向对象的思想，设计出来的结构都是树状的，最大程度的提升代码的复用率、扩展性、易读性。但是这里有个问题，树状结构大家都是知道是一种关系型结构，擅长处理关系结构，扩展等方面适合业务功能核心代码的开发。但是对于一些重复的、每个功能都需要用到的功能比如，日志、监控、权限、统计、事务等横向的功能（所有功能都需要的），使用面向对象的思想处理起来的结果就是导致代码重复率高、不易扩展、阅读体验比较差，每次都要看非业务代码。这种情况就适合用切面来处理。因为这个过程和织布机，横向织入横线的过程一样，所以这个过程被称为织入。

关键点

切面的核心点，就是切入点，point，我们需要一个切入点 point cut，围绕这个点进行一些增强处理，可能是前，后，或者环绕式的，这些具体的增强就是advice，而切面 aspect 是包含这两个部分的。但是切面生成之后，如果放到合适的地方，就是需要织入 weaving。

spring中的应用

面向对象的设计中，一个类有两部分组成，成员变量，成员方法。成员变量是属性，运行时标识当前对象的状态，成员方法是action，标识这个类可以做哪些事情。所以AOP增强的最小单位就是成员方法，是对方法的增强。但是方法属于类，所以切入点的通过规则表达式（可以理解过正则表达式）来选定类+方法，具体规则看
所以增强的单位肯定也是方法，可以理解为方法增强。最后的织入过程，我们都知道设计模式中的代理模式，这里就是基于代理模式的思想，通过spring的IOC机制生成代理对象，spring通过IOC获取的都是代理对象，所以很方便的就完成了织入过程。
基于以上的概念，spring aop是分开设计了4种接口

spring中的设计

切入点，主要是用来解析表达式，并且进行类、方法的 match操作，PointCut
增强器，主要用来对方法进行增强：Advice
切面，切入点和增强器的组合具体是流程控制： PointCutAdvisor
织入，获取目标对象是否需要进行代理，如果需要则获取需要进行代理的切面（可能有多个），生成代理对象放入到容器中替换目标对象，AutoProxyCreator

类图

Demo

主入口 main

public class InstalmentApiServer {
  public static void main(String[] args) {
    System.getProperties().put("sun.misc.ProxyGenerator.saveGeneratedFiles", "true");
    log.info("starting main");
    ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[]{
        "classpath:context/applicationContext.xml",
 }, false);
    IHello testA = (IHello) context.getBean("testA");
    testA.sayHello();

xml 配置文件

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd
    http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd"
    default-lazy-init="false">
  
  <aop:aspectj-autoproxy/>
  <bean id="testA" class="com.xiaomi.mifi.instalment.api.server.TestA" init-method="initMethod"> </bean>
  <bean id="logAspect" class="com.xiaomi.mifi.instalment.api.server.LogAspect" />
  <!--注册annotation-->
  <context:annotation-config/>
</beans>

切面 LogAspect

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;

@Aspect
public class LogAspect {
  @Around("execution(* com..*(..))")
  private Object errorHandlerAround(ProceedingJoinPoint joinPoint) throws Throwable {
    System.out.println("-----------> LogAspect before");
    Object rs =  joinPoint.proceed();
    System.out.println("-----------> LogAspect After");
    return rs;
  }
}

HelloImpl

public class HelloImpl implements  IHello{
  @Override
  public void sayHello() {
    System.out.println("hello world");
  }
}

TestA

import org.springframework.beans.factory.InitializingBean;
import javax.annotation.PostConstruct;

public class TestA implements InitializingBean , IHello{

  public TestA() {
    System.out.println("---->TestA constructor this is ");
  }

  @PostConstruct
  public void init() {
    System.out.println("PostConstruct");
  }

  public void initMethod() {
    System.out.println("initMethod");
  }

  public void fooA() {
    System.out.println("----> TestA.fooA this is ");
  }

  public void foo() {
    System.out.println("----> TestA.foo this is ");
  }

  @Override
  public void afterPropertiesSet() throws Exception {
    System.out.println("afterPropertiesSet");
  }

  @Override
  public void sayHello() {
    System.out.println("----> TestA sayHello implement ");
  }
}

开启aop配置

这个触发操作是由于配置

// spring 配置文件, 启动spring AOP
<beans  // aop 命令空间
       xmlns:aop="http://www.springframework.org/schema/aop"
      http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd"
    default-lazy-init="false">
   // 开启  aop配置
<aop:aspectj-autoproxy/>

aop地址空间映射

org.springframework.aop.config.AopNamespaceHandler
这个类用来解析xml配置文件中，aop开头的配置
这个aop命令空间（http://www.springframework.org/schema/aop） 是如何映射到这个类是通过配置文件spring.handlers，来完成的，这个文件在
srping-aop-4.3.30.jar包的，META-INF 目录下面的，spring会加载所有这个名称的文件，用来解析xml文件中的命令空间的
文件内容

http\://www.springframework.org/schema/aop=org.springframework.aop.config.AopNamespaceHandler

aop属性解析

org.springframework.aop.config.AopNamespaceHandler

@Override
public void init() {
   // In 2.0 XSD as well as in 2.5+ XSDs
   registerBeanDefinitionParser("config", new ConfigBeanDefinitionParser());
   // 属性  aspectj-autoproxy 的解析
   registerBeanDefinitionParser("aspectj-autoproxy", new AspectJAutoProxyBeanDefinitionParser());
   registerBeanDefinitionDecorator("scoped-proxy", new ScopedProxyBeanDefinitionDecorator());

   // Only in 2.0 XSD: moved to context namespace in 2.5+
   registerBeanDefinitionParser("spring-configured", new SpringConfiguredBeanDefinitionParser());
}

aop解析细节

具体的细节就是使用AnnotationAwareAspectJAutoProxyCreator类，去向
BeanDefinitionRegistry把beanDefinition注册到工厂类中，bean的创建过程是先创建bena的定义，通过bean的定义再生成的对象。
通过下面的方法完成类：AnnotationAwareAspectJAutoProxyCreator的注册，所有aop的增强都是通过这个类来完成的如果是通过@Aspect注解，注解的切面。
该类的优先级别是最高级别的，先执行

return registerOrEscalateApcAsRequired(AnnotationAwareAspectJAutoProxyCreator.class, registry, source);

生成代理类

AbstractAutoProxyCreator
是 AnnotationAwareAspectJAutoProxyCreator 的祖先类的，实现对类的增强是流程主入口。
AnnotationAwareAspectJAutoProxyCreator本身只处理和Aspect注解相关的事情，充分体现面向对象
抽象、继承，的特点，体现了高扩展能力。

主流程

org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator
AbstractAutowireCapableBeanFactory.initializeBean
->applyBeanPostProcessorsAfterInitialization
开始执行 .postProcessAfterInitialization

// spring 解决单例循环依赖的时候，会提前注册一个BeanFactory，这里会提前生成代理类
@Override
public Object getEarlyBeanReference(Object bean, String beanName) throws BeansException {
   Object cacheKey = getCacheKey(bean.getClass(), beanName);
   // 写入这个map的原因，是为了保证单例，这里提前生成了代理类（因为循环依赖），
   // A->B->A , 这种情况下，在创建B的时候，会调用这里提前生成A的代理类，
   // 这个时候B里面的对A的引用已经是新的代理类了，但是A本身的还在初始化的过程中还没完成
   // 需要完成A的初始化，但是还不能重新生成新的代理类否则就不是单例了，所以这里记录
   // 在postProcessAfterInitialization的时候，对比引用，如果一样，就不重新生成代理类了
   // 同时这个方法只会被调用一次，因为单例对象生成过成中会加锁，而且进行缓存，保证创建完成之后
   // 只会从缓存里面取。同时最终A初始化完成之后，会把最终返回的引用对象体会为这里生成的代理对象，保证单例
   this.earlyProxyReferences.put(cacheKey, bean);
   // 生成代理类的具体实现
   return wrapIfNecessary(bean, beanName, cacheKey);
}

// 正常的非循环依赖的对象，都从这里进行AOP的增强
// 这里的循环依赖指的是单例循环依赖（非构造函数依赖）
@Override
public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
   if (bean != null) {
      Object cacheKey = getCacheKey(bean.getClass(), beanName);
      // 1， 如果是循环依赖则remove返回的bean ，和 当前是bean地址一样，这里是false，直接结束
      // 2, 非循环依赖，那这里remove返回的是null，而bean不为空是先决条件，所以这里返回 true，进行类的增强，生成代理类
      if (this.earlyProxyReferences.remove(cacheKey) != bean) {
         // 生成代理类的具体实现
         return wrapIfNecessary(bean, beanName, cacheKey);
      }
   }
   return bean;
}

// 生成代理类
protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) {
   if (beanName != null && 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.
   //获取需要增强的切面
   Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);
   if (specificInterceptors != DO_NOT_PROXY) {
      // 缓存该类，需要 AOP 增强
      this.advisedBeans.put(cacheKey, Boolean.TRUE);
      // 生成代理类对象
      Object proxy = createProxy(
            bean.getClass(), beanName, specificInterceptors
             // 被代理的对象，在代理类最后调用
            , new SingletonTargetSource(bean));
       // 缓存
      this.proxyTypes.put(cacheKey, proxy.getClass());
      return proxy;
   }
   // 缓存该类，不需要 AOP 增强
   this.advisedBeans.put(cacheKey, Boolean.FALSE);
   return bean;
}

// 生成代理类
protected Object createProxy(
      Class<?> beanClass, String beanName, Object[] specificInterceptors, TargetSource targetSource) {
   // 设置属性，把原始类名称，设置到 BeanDefiniiton的属性中
   if (this.beanFactory instanceof ConfigurableListableBeanFactory) {
      AutoProxyUtils.exposeTargetClass((ConfigurableListableBeanFactory) this.beanFactory, beanName, beanClass);
   }

   ProxyFactory proxyFactory = new ProxyFactory();
   proxyFactory.copyFrom(this);
   // 检查类，是需要代理类，还是代理接口，因为有的类没有接口，只能代理类
   // java JDK proxy只能代理接口，如果是代理类需要使用cgLib生成子类才行
   if (!proxyFactory.isProxyTargetClass()) {
       // 检查类属性是否有生命
      if (shouldProxyTargetClass(beanClass, beanName)) {
         proxyFactory.setProxyTargetClass(true);
      }
      else {
         // 如果实现的类是内部类，最后也会代理类
         // proxyFactory.setProxyTargetClass(true);
         evaluateProxyInterfaces(beanClass, proxyFactory);
      }
   }
   // 生成最终的增强器
   Advisor[] advisors = buildAdvisors(beanName, specificInterceptors);
   proxyFactory.addAdvisors(advisors);
   proxyFactory.setTargetSource(targetSource);
   customizeProxyFactory(proxyFactory);

   proxyFactory.setFrozen(this.freezeProxy);
   if (advisorsPreFiltered()) {
      proxyFactory.setPreFiltered(true);
   }
    // 生成代理对象
   return proxyFactory.getProxy(getProxyClassLoader());
}

// 检查是否需要代理类
protected void evaluateProxyInterfaces(Class<?> beanClass, ProxyFactory proxyFactory) {
   Class<?>[] targetInterfaces = ClassUtils.getAllInterfacesForClass(beanClass, getProxyClassLoader());
   boolean hasReasonableProxyInterface = false;
   for (Class<?> ifc : targetInterfaces) {
      if (!isConfigurationCallbackInterface(ifc) && !isInternalLanguageInterface(ifc) &&
            ifc.getMethods().length > 0) {
         hasReasonableProxyInterface = true;
         break;
      }
   }
   // 有需要代理的接口，则添加代理接口，这里有个问题，就是只能代理接口的方法，
  //   非接口方法无法代理，即使符合pointCut的条件
   if (hasReasonableProxyInterface) {
      // Must allow for introductions; can't just set interfaces to the target's interfaces only.
      for (Class<?> ifc : targetInterfaces) {
         proxyFactory.addInterface(ifc);
      }
   }
   else {
     // 否则只能代理类
      proxyFactory.setProxyTargetClass(true);
   }
}

// 生成最终的advisor 
protected Advisor[] buildAdvisors(String beanName, Object[] specificInterceptors) {
   // Handle prototypes correctly...
   // 通过配置文件配置的，目前都是通过注解，所以这里一般都是空的
   Advisor[] commonInterceptors = resolveInterceptorNames();

   List<Object> allInterceptors = new ArrayList<Object>();
   if (specificInterceptors != null) {
      allInterceptors.addAll(Arrays.asList(specificInterceptors));
      if (commonInterceptors.length > 0) {
         if (this.applyCommonInterceptorsFirst) {
            allInterceptors.addAll(0, Arrays.asList(commonInterceptors));
         }
         else {
            allInterceptors.addAll(Arrays.asList(commonInterceptors));
         }
      }
   }
   Advisor[] advisors = new Advisor[allInterceptors.size()];
   for (int i = 0; i < allInterceptors.size(); i++) {
      // wrap 是进行一次适配的过程，因为要兼容老的切面，所以进行一次兼容处理
      advisors[i] = this.advisorAdapterRegistry.wrap(allInterceptors.get(i));
   }
   return advisors;
}

获取该对象需要增强的切面

org.springframework.aop.framework.autoproxy.AbstractAdvisorAutoProxyCreator
是 org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator
的子类，提供和切面相关的逻辑

@Override
protected Object[] getAdvicesAndAdvisorsForBean(Class<?> beanClass, String beanName, TargetSource targetSource) {
   List<Advisor> advisors = findEligibleAdvisors(beanClass, beanName);
   if (advisors.isEmpty()) {
      return DO_NOT_PROXY;
   }
   return advisors.toArray();
}


protected List<Advisor> findEligibleAdvisors(Class<?> beanClass, String beanName) {
   // 获取所有的切面， 注意是逻辑见AnnotationAwareAspectJAutoProxyCreator
   List<Advisor> candidateAdvisors = findCandidateAdvisors();
   // 取出符合该对象的切面
   List<Advisor> eligibleAdvisors = findAdvisorsThatCanApply(candidateAdvisors, beanClass, beanName);
   // 扩展切面，这个是因为有一些切面比较老，需要去兼容一些，做一些适配
   extendAdvisors(eligibleAdvisors);
   if (!eligibleAdvisors.isEmpty()) {
      // 切面排序，决定执行先后顺序
      eligibleAdvisors = sortAdvisors(eligibleAdvisors);
   }
   return eligibleAdvisors;
}

获取Aspect所有的切面

对Aspect注解，进行解析，获取所有的Aspect注解，切面
以及表达式
org.springframework.aop.aspectj.annotation.AnnotationAwareAspectJAutoProxyCreator
主流程

@Override
protected List findCandidateAdvisors() {
   // 先调用父类接口，兼容父类
   List advisors = super.findCandidateAdvisors();
   // 获取Aspect注解的切面
   advisors.addAll(this.aspectJAdvisorsBuilder.buildAspectJAdvisors());
   return advisors;
}

// 获取增强列表， 
// 来自类：org.springframework.aop.aspectj.annotation.BeanFactoryAspectJAdvisorsBuilder
public List buildAspectJAdvisors() {
   List aspectNames = this.aspectBeanNames;

   if (aspectNames == null) {
      // 加锁，防止重复操作
      synchronized (this) {
          aspectNames = this.aspectBeanNames;
           // double check 
         if (aspectNames == null) {
            List advisors = new LinkedList();
            aspectNames = new LinkedList();
           // 由于Aspect注解本身无法直接识别，所以通过这种方式获取所有的已经
            // 这个地方会获取所有的bean，包含继承Object的子类，由于Asject注解，的类本身是没有类型的
            // 所以这里使用Object获取所有的，调用这个方法会进行缓存
            //所以没有直接调用this.beanFactory.getBeanDefinitionNames 这个方法
           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.
               Class beanType = this.beanFactory.getType(beanName);
               if (beanType == null) {
                  continue;
               }
               // 判断是否有Aspect注解
               if (this.advisorFactory.isAspect(beanType)) {
                  aspectNames.add(beanName);
                  AspectMetadata amd = new AspectMetadata(beanType, beanName);
                  if (amd.getAjType().getPerClause().getKind() == PerClauseKind.SINGLETON) {
                     // 创建工厂类，这个工厂类只包含当前aspect一个beanName,为了后续生成advice使用
                    MetadataAwareAspectInstanceFactory factory =
                           new BeanFactoryAspectInstanceFactory(this.beanFactory, beanName);
                    // 解析Aspect注解的类，获取方法上面的注解，每个增强方法都是一个切面增强
                    // 具体的可以看下代码细节，比较简单就是解析 Around After before这些注解
                    List classAdvisors = this.advisorFactory.getAdvisors(factory);
                     if (this.beanFactory.isSingleton(beanName)) {
                        this.advisorsCache.put(beanName, classAdvisors);
                     }
                     else {
                        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();
   }
   List advisors = new LinkedList();
   for (String aspectName : aspectNames) {
      // 单例
      List cachedAdvisors = this.advisorsCache.get(aspectName);
      if (cachedAdvisors != null) {
         advisors.addAll(cachedAdvisors);
      }
      else {
         // 非单例的每次都需要通过工厂类生成新的对象
         MetadataAwareAspectInstanceFactory factory = this.aspectFactoryCache.get(aspectName);
         advisors.addAll(this.advisorFactory.getAdvisors(factory));
      }
   }
   return advisors;
}

获取类里面的增强器

// 获取@aspect 注解类中的 advice 
@Override
public List<Advisor> getAdvisors(MetadataAwareAspectInstanceFactory aspectInstanceFactory) {
   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.
   // 为了延迟初始化对象
   MetadataAwareAspectInstanceFactory lazySingletonAspectInstanceFactory =
         new LazySingletonAspectInstanceFactoryDecorator(aspectInstanceFactory);

   List<Advisor> advisors = new ArrayList<Advisor>();
   // 过滤掉pointCut 切面注解， 
   for (Method method : getAdvisorMethods(aspectClass)) {
      // 获取所有的注解方法， @around @before等
      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;
}
// 
@Override
public Advisor getAdvisor(Method candidateAdviceMethod, MetadataAwareAspectInstanceFactory aspectInstanceFactory,
      int declarationOrderInAspect, String aspectName) {

   validate(aspectInstanceFactory.getAspectMetadata().getAspectClass());

   AspectJExpressionPointcut expressionPointcut = getPointcut(
         candidateAdviceMethod, aspectInstanceFactory.getAspectMetadata().getAspectClass());
   if (expressionPointcut == null) {
      return null;
   }
    // 这里会根据注解 @around before after 生成不同的advice实现类
   return new InstantiationModelAwarePointcutAdvisorImpl(expressionPointcut, candidateAdviceMethod,
         this, aspectInstanceFactory, declarationOrderInAspect, aspectName);
}

// 
public InstantiationModelAwarePointcutAdvisorImpl(AspectJExpressionPointcut declaredPointcut,
      Method aspectJAdviceMethod, AspectJAdvisorFactory aspectJAdvisorFactory,
      MetadataAwareAspectInstanceFactory aspectInstanceFactory, int declarationOrder, String aspectName) {

   this.declaredPointcut = declaredPointcut;
   this.declaringClass = aspectJAdviceMethod.getDeclaringClass();
   this.methodName = aspectJAdviceMethod.getName();
   this.parameterTypes = aspectJAdviceMethod.getParameterTypes();
   this.aspectJAdviceMethod = aspectJAdviceMethod;
   this.aspectJAdvisorFactory = aspectJAdvisorFactory;
   this.aspectInstanceFactory = aspectInstanceFactory;
   this.declarationOrder = declarationOrder;
   this.aspectName = aspectName;
  // A singleton aspect.
      this.pointcut = this.declaredPointcut;
      this.lazy = false;
      // 这里进行advice的初始化
      this.instantiatedAdvice = instantiateAdvice(this.declaredPointcut);
   
}
// 实例化增强器 advice
private Advice instantiateAdvice(AspectJExpressionPointcut pcut) {
                return this.aspectJAdvisorFactory.getAdvice(this.aspectJAdviceMethod, pcut,
                                this.aspectInstanceFactory, this.declarationOrder, this.aspectName);
        }
// 根据不同的注解，生成不同的advice实例，代理的时候调用的是这个实例        
@Override
public Advice getAdvice(Method candidateAdviceMethod, AspectJExpressionPointcut expressionPointcut,
      MetadataAwareAspectInstanceFactory aspectInstanceFactory, int declarationOrder, String aspectName) {

   Class candidateAspectClass = aspectInstanceFactory.getAspectMetadata().getAspectClass();
   validate(candidateAspectClass);

   AspectJAnnotation aspectJAnnotation =
         AbstractAspectJAdvisorFactory.findAspectJAnnotationOnMethod(candidateAdviceMethod);
   if (aspectJAnnotation == null) {
      return null;
   }

   // If we get here, we know we have an AspectJ method.
   // Check that it's an AspectJ-annotated class
   if (!isAspect(candidateAspectClass)) {
      throw new AopConfigException("Advice must be declared inside an aspect type: " +
            "Offending method '" + candidateAdviceMethod + "' in class [" +
            candidateAspectClass.getName() + "]");
   }

   if (logger.isDebugEnabled()) {
      logger.debug("Found AspectJ method: " + candidateAdviceMethod);
   }

   AbstractAspectJAdvice springAdvice;

   switch (aspectJAnnotation.getAnnotationType()) {
      case AtPointcut:
         if (logger.isDebugEnabled()) {
            logger.debug("Processing pointcut '" + candidateAdviceMethod.getName() + "'");
         }
         return null;
         // around 注解，
      case AtAround:
         // 这里把facotyr作为参数放进去，是为了延迟获取实例化对象，等需要的时候再生成
         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);
   }

   // Now to configure the advice...
   springAdvice.setAspectName(aspectName);
   springAdvice.setDeclarationOrder(declarationOrder);
   String[] argNames = this.parameterNameDiscoverer.getParameterNames(candidateAdviceMethod);
   if (argNames != null) {
      springAdvice.setArgumentNamesFromStringArray(argNames);
   }
   springAdvice.calculateArgumentBindings();

   return springAdvice;
}

获取符合当前bean的切面

pointCut表达式文档

// 匹配符合条件的切面
protected List findAdvisorsThatCanApply(
      List candidateAdvisors, Class beanClass, String beanName) {

   // 设置到 ThrealLocal里面，其他地方会调用这个来进行切面的匹配，从这里获取要增强的类
   // 决定是否要进行增强
   ProxyCreationContext.setCurrentProxiedBeanName(beanName);
   try {
      return AopUtils.findAdvisorsThatCanApply(candidateAdvisors, beanClass);
   }
   finally {
      // 清除 ThrealLocal
      ProxyCreationContext.setCurrentProxiedBeanName(null);
   }
}

//  org.springframework.aop.support.AopUtils
public static List findAdvisorsThatCanApply(List candidateAdvisors, Class clazz) {
   if (candidateAdvisors.isEmpty()) {
      return candidateAdvisors;
   }
   for (Advisor candidate : candidateAdvisors) {
      if (candidate instanceof IntroductionAdvisor) {
         // already processed
         continue;
      }
      // Spring Aop Aspect 注解走的都是这里
      if (canApply(candidate, clazz, hasIntroductions)) {
         eligibleAdvisors.add(candidate);
      }
   }
   return eligibleAdvisors;
}
//  org.springframework.aop.support.AopUtils
public static boolean canApply(Advisor advisor, Class targetClass, boolean hasIntroductions) {
   if (advisor instanceof IntroductionAdvisor) {
      return ((IntroductionAdvisor) advisor).getClassFilter().matches(targetClass);
   }
   // 走这里，切面增强
   else if (advisor instanceof PointcutAdvisor) {
      PointcutAdvisor pca = (PointcutAdvisor) advisor;
      return canApply(pca.getPointcut(), targetClass, hasIntroductions);
   }
   else {
      // It doesn't have a pointcut so we assume it applies.
      return true;
   }
}

//  org.springframework.aop.support.AopUtils
public static boolean canApply(Pointcut pc, Class targetClass, boolean hasIntroductions) {
   Assert.notNull(pc, "Pointcut must not be null");
   // 类过滤，如果类不符合条件，直接结束，看了一点没看明白，大概意思就是进行字符串匹配，
   // 但是匹配方式比较复杂
   if (!pc.getClassFilter().matches(targetClass)) {
      return false;
   }
   
   MethodMatcher methodMatcher = pc.getMethodMatcher();
   if (methodMatcher == MethodMatcher.TRUE) {
      // No need to iterate the methods if we're matching any method anyway...
      return true;
   }

   IntroductionAwareMethodMatcher introductionAwareMethodMatcher = null;
   if (methodMatcher instanceof IntroductionAwareMethodMatcher) {
      introductionAwareMethodMatcher = (IntroductionAwareMethodMatcher) methodMatcher;
   }
   // 获取该类的实现的所有接口类
   Set> classes = new LinkedHashSet>(ClassUtils.getAllInterfacesForClassAsSet(targetClass));
   // 把当前类添加进去
   classes.add(targetClass);
   // 遍历当前类以及其所有接口类的，所有方法，先遍历接口，最后遍历当前类
   for (Class clazz : classes) {
      Method[] methods = ReflectionUtils.getAllDeclaredMethods(clazz);
      for (Method method : methods) {
         if ((introductionAwareMethodMatcher != null &&
               // 方法匹配，具体实现细节没有看懂
               introductionAwareMethodMatcher.matches(method, targetClass, hasIntroductions)) ||
               // 更大范围的匹配，大概就是把类，入参，返回值等拆成不同的token 进行匹配，具体实现细节没有看懂
               methodMatcher.matches(method, targetClass)) {
             // 只要有一个方法符合条件则直接返回，快速返回，
             // 因为只要有一个就必须生成代理类了，没必要遍历所有的方法
            return true;
         }
      }
   }

   return false;
}

获取代理工厂生成代理类

// 来自 org.springframework.aop.framework.DefaultAopProxyFactory
// 先根据配置，或者当前类的情况，生成代理工厂类，如果该类一个自定义接口都没有实现
// 则会使用CGLib进行代理，通过生成子类的方式，增强需要增强的方法。
// 否则使用JDk动态代理工厂类，但是该类只会生成接口包含的方法的代理类，不会对实现类内所有方法都进行代理
// 总之都是有条件的，对于符合条件的方法进行代理。但是JDK动态代理生成的代理对象的类型必须是其实现的
// 接口否则会因为类型不匹配报错。
@Override
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() || Proxy.isProxyClass(targetClass)) {
         return new JdkDynamicAopProxy(config);
      }
      // 代理类，使用Cglib
      return new ObjenesisCglibAopProxy(config);
   }
   else {
       //代理接口，JDK动态代理
      return new JdkDynamicAopProxy(config);
   }
}

// 来自 org.springframework.aop.framework.JdkDynamicAopProxy
@Override
public Object getProxy(ClassLoader classLoader) {
   // 获取所有需要代理的接口，这里会新增一些springAOP特有的接口
   Class<?>[] proxiedInterfaces = AopProxyUtils.completeProxiedInterfaces(this.advised, true);
   // 检查、标识，是否有，equal ，hashCode, 方法，没有需要特殊处理
   findDefinedEqualsAndHashCodeMethods(proxiedInterfaces);
   // 使用JDK动态代理，生成代理类，具体的可以看下面的生成的代理类
   // 这里使用this当前对象是因为，具体的操作要由该对象来完成，每个需要代理的对象都会新生成一个该对象
   //该类实现了InvocationHandler接口，具体代理在invoder方法中 final class JdkDynamicAopProxy implements AopProxy, InvocationHandler,  {
   return Proxy.newProxyInstance(classLoader, proxiedInterfaces, this);
}
// 来自  org.springframework.aop.framework.AopProxyUtils
static Class<?>[] completeProxiedInterfaces(AdvisedSupport advised, boolean decoratingProxy) {
                Class<?>[] specifiedInterfaces = advised.getProxiedInterfaces();
                if (specifiedInterfaces.length == 0) {
                        // No user-specified interfaces: check whether target class is an interface.
                        Class<?> targetClass = advised.getTargetClass();
                        if (targetClass != null) {
                                if (targetClass.isInterface()) {
                                        advised.setInterfaces(targetClass);
                                }
                                else if (Proxy.isProxyClass(targetClass)) {
                                        advised.setInterfaces(targetClass.getInterfaces());
                                }
                                specifiedInterfaces = advised.getProxiedInterfaces();
                        }
                }
                // 如果没有，则需要代理该接口, 该接口没有具体方法，只是用来标识是是最顶层的抽象定义接口，划分类别
                boolean addSpringProxy = !advised.isInterfaceProxied(SpringProxy.class);
                // 如果没有，则需要代理该接口， 这个里面有所有增强器需要的基础方法，但是默认JDK动态代理都已经实现了
                boolean addAdvised = !advised.isOpaque() && !advised.isInterfaceProxied(Advised.class);
                // 如果没有，则需要代理该接口
                boolean addDecoratingProxy = (decoratingProxy && !advised.isInterfaceProxied(DecoratingProxy.class));
                int nonUserIfcCount = 0;
                if (addSpringProxy) {
                        nonUserIfcCount++;
                }
                if (addAdvised) {
                        nonUserIfcCount++;
                }
                if (addDecoratingProxy) {
                        nonUserIfcCount++;
                }
                Class<?>[] proxiedInterfaces = new Class<?>[specifiedInterfaces.length + nonUserIfcCount];
                System.arraycopy(specifiedInterfaces, 0, proxiedInterfaces, 0, specifiedInterfaces.length);
                int index = specifiedInterfaces.length;
                if (addSpringProxy) {
                        proxiedInterfaces[index] = SpringProxy.class;
                        index++;
                }
                if (addAdvised) {
                        proxiedInterfaces[index] = Advised.class;
                        index++;
                }
                if (addDecoratingProxy) {
                        proxiedInterfaces[index] = DecoratingProxy.class;
                }
                return proxiedInterfaces;
        }
// 来自    org.springframework.aop.framework.DefaultAopProxyFactory  
// 查找其接口中，是否包含的有 equal , hashCode 两个方法 
// 因为要是没有的话就需要进行特殊处理，因为这两个方法是必须要要有的，属于所有对象都有的
// 因为所有对象都继承自 Object类
private void findDefinedEqualsAndHashCodeMethods(Class<?>[] proxiedInterfaces) {
                for (Class<?> proxiedInterface : proxiedInterfaces) {
                        Method[] methods = proxiedInterface.getDeclaredMethods();
                        for (Method method : methods) {
                                if (AopUtils.isEqualsMethod(method)) {
                                        this.equalsDefined = true;
                                }
                                if (AopUtils.isHashCodeMethod(method)) {
                                        this.hashCodeDefined = true;
                                }
                                if (this.equalsDefined && this.hashCodeDefined) {
                                        return;
                                }
                        }
                }
        }

JDK动态代理生成的代理类

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by FernFlower decompiler)
//

package com.sun.proxy;

import com.xiaomi.mifi.instalment.api.server.IHello;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.lang.reflect.UndeclaredThrowableException;
import org.aopalliance.aop.Advice;
import org.springframework.aop.Advisor;
import org.springframework.aop.SpringProxy;
import org.springframework.aop.TargetSource;
import org.springframework.aop.framework.Advised;
import org.springframework.aop.framework.AopConfigException;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.core.DecoratingProxy;

public final class $Proxy9 extends Proxy implements InitializingBean, IHello, SpringProxy, Advised, DecoratingProxy {
  private static Method m1;
  private static Method m15;
  private static Method m26;
  private static Method m22;
  private static Method m17;
  private static Method m12;
  private static Method m5;
  private static Method m21;
  private static Method m10;
  private static Method m9;
  private static Method m0;
  private static Method m13;
  private static Method m19;
  private static Method m25;
  private static Method m23;
  private static Method m2;
  private static Method m27;
  private static Method m14;
  private static Method m28;
  private static Method m16;
  private static Method m6;
  private static Method m7;
  private static Method m18;
  private static Method m24;
  private static Method m4;
  private static Method m3;
  private static Method m20;
  private static Method m8;
  private static Method m11;

  public $Proxy9(InvocationHandler var1) throws  {
    super(var1);
  }

  public final boolean equals(Object var1) throws  {
    try {
      // super.h 指的是org.springframework.aop.framework.JdkDynamicAopProxy
      // 类生成的对象，invoder 就是其invoder方法，具体看下面的调用流程
      return (Boolean)super.h.invoke(this, m1, new Object[]{var1});
    } catch (RuntimeException | Error var3) {
      throw var3;
    } catch (Throwable var4) {
      throw new UndeclaredThrowableException(var4);
    }
  }

  public final void addAdvisor(Advisor var1) throws AopConfigException {
    try {
      super.h.invoke(this, m15, new Object[]{var1});
    } catch (RuntimeException | Error var3) {
      throw var3;
    } catch (Throwable var4) {
      throw new UndeclaredThrowableException(var4);
    }
  }

  public final boolean isExposeProxy() throws  {
    try {
      return (Boolean)super.h.invoke(this, m26, (Object[])null);
    } catch (RuntimeException | Error var2) {
      throw var2;
    } catch (Throwable var3) {
      throw new UndeclaredThrowableException(var3);
    }
  }

  public final boolean isProxyTargetClass() throws  {
    try {
      return (Boolean)super.h.invoke(this, m22, (Object[])null);
    } catch (RuntimeException | Error var2) {
      throw var2;
    } catch (Throwable var3) {
      throw new UndeclaredThrowableException(var3);
    }
  }

  public final void removeAdvisor(int var1) throws AopConfigException {
    try {
      super.h.invoke(this, m17, new Object[]{var1});
    } catch (RuntimeException | Error var3) {
      throw var3;
    } catch (Throwable var4) {
      throw new UndeclaredThrowableException(var4);
    }
  }

  public final Class[] getProxiedInterfaces() throws  {
    try {
      return (Class[])super.h.invoke(this, m12, (Object[])null);
    } catch (RuntimeException | Error var2) {
      throw var2;
    } catch (Throwable var3) {
      throw new UndeclaredThrowableException(var3);
    }
  }

  public final int indexOf(Advisor var1) throws  {
    try {
      return (Integer)super.h.invoke(this, m5, new Object[]{var1});
    } catch (RuntimeException | Error var3) {
      throw var3;
    } catch (Throwable var4) {
      throw new UndeclaredThrowableException(var4);
    }
  }

  public final TargetSource getTargetSource() throws  {
    try {
      return (TargetSource)super.h.invoke(this, m21, (Object[])null);
    } catch (RuntimeException | Error var2) {
      throw var2;
    } catch (Throwable var3) {
      throw new UndeclaredThrowableException(var3);
    }
  }

  public final void addAdvice(int var1, Advice var2) throws AopConfigException {
    try {
      super.h.invoke(this, m10, new Object[]{var1, var2});
    } catch (RuntimeException | Error var4) {
      throw var4;
    } catch (Throwable var5) {
      throw new UndeclaredThrowableException(var5);
    }
  }

  public final void addAdvice(Advice var1) throws AopConfigException {
    try {
      super.h.invoke(this, m9, new Object[]{var1});
    } catch (RuntimeException | Error var3) {
      throw var3;
    } catch (Throwable var4) {
      throw new UndeclaredThrowableException(var4);
    }
  }

  public final int hashCode() throws  {
    try {
      return (Integer)super.h.invoke(this, m0, (Object[])null);
    } catch (RuntimeException | Error var2) {
      throw var2;
    } catch (Throwable var3) {
      throw new UndeclaredThrowableException(var3);
    }
  }

  public final boolean isInterfaceProxied(Class var1) throws  {
    try {
      return (Boolean)super.h.invoke(this, m13, new Object[]{var1});
    } catch (RuntimeException | Error var3) {
      throw var3;
    } catch (Throwable var4) {
      throw new UndeclaredThrowableException(var4);
    }
  }

  public final boolean removeAdvice(Advice var1) throws  {
    try {
      return (Boolean)super.h.invoke(this, m19, new Object[]{var1});
    } catch (RuntimeException | Error var3) {
      throw var3;
    } catch (Throwable var4) {
      throw new UndeclaredThrowableException(var4);
    }
  }

  public final void setExposeProxy(boolean var1) throws  {
    try {
      super.h.invoke(this, m25, new Object[]{var1});
    } catch (RuntimeException | Error var3) {
      throw var3;
    } catch (Throwable var4) {
      throw new UndeclaredThrowableException(var4);
    }
  }

  public final void setTargetSource(TargetSource var1) throws  {
    try {
      super.h.invoke(this, m23, new Object[]{var1});
    } catch (RuntimeException | Error var3) {
      throw var3;
    } catch (Throwable var4) {
      throw new UndeclaredThrowableException(var4);
    }
  }

  public final String toString() throws  {
    try {
      return (String)super.h.invoke(this, m2, (Object[])null);
    } catch (RuntimeException | Error var2) {
      throw var2;
    } catch (Throwable var3) {
      throw new UndeclaredThrowableException(var3);
    }
  }

  public final Class getTargetClass() throws  {
    try {
      return (Class)super.h.invoke(this, m27, (Object[])null);
    } catch (RuntimeException | Error var2) {
      throw var2;
    } catch (Throwable var3) {
      throw new UndeclaredThrowableException(var3);
    }
  }

  public final void addAdvisor(int var1, Advisor var2) throws AopConfigException {
    try {
      super.h.invoke(this, m14, new Object[]{var1, var2});
    } catch (RuntimeException | Error var4) {
      throw var4;
    } catch (Throwable var5) {
      throw new UndeclaredThrowableException(var5);
    }
  }

  public final Class getDecoratedClass() throws  {
    try {
      return (Class)super.h.invoke(this, m28, (Object[])null);
    } catch (RuntimeException | Error var2) {
      throw var2;
    } catch (Throwable var3) {
      throw new UndeclaredThrowableException(var3);
    }
  }

  public final boolean removeAdvisor(Advisor var1) throws  {
    try {
      return (Boolean)super.h.invoke(this, m16, new Object[]{var1});
    } catch (RuntimeException | Error var3) {
      throw var3;
    } catch (Throwable var4) {
      throw new UndeclaredThrowableException(var4);
    }
  }

  public final int indexOf(Advice var1) throws  {
    try {
      return (Integer)super.h.invoke(this, m6, new Object[]{var1});
    } catch (RuntimeException | Error var3) {
      throw var3;
    } catch (Throwable var4) {
      throw new UndeclaredThrowableException(var4);
    }
  }

  public final boolean isFrozen() throws  {
    try {
      return (Boolean)super.h.invoke(this, m7, (Object[])null);
    } catch (RuntimeException | Error var2) {
      throw var2;
    } catch (Throwable var3) {
      throw new UndeclaredThrowableException(var3);
    }
  }

  public final boolean replaceAdvisor(Advisor var1, Advisor var2) throws AopConfigException {
    try {
      return (Boolean)super.h.invoke(this, m18, new Object[]{var1, var2});
    } catch (RuntimeException | Error var4) {
      throw var4;
    } catch (Throwable var5) {
      throw new UndeclaredThrowableException(var5);
    }
  }

  public final void setPreFiltered(boolean var1) throws  {
    try {
      super.h.invoke(this, m24, new Object[]{var1});
    } catch (RuntimeException | Error var3) {
      throw var3;
    } catch (Throwable var4) {
      throw new UndeclaredThrowableException(var4);
    }
  }

  public final void sayHello() throws  {
    try {
      super.h.invoke(this, m4, (Object[])null);
    } catch (RuntimeException | Error var2) {
      throw var2;
    } catch (Throwable var3) {
      throw new UndeclaredThrowableException(var3);
    }
  }

  public final void afterPropertiesSet() throws Exception {
    try {
      super.h.invoke(this, m3, (Object[])null);
    } catch (Exception | Error var2) {
      throw var2;
    } catch (Throwable var3) {
      throw new UndeclaredThrowableException(var3);
    }
  }

  public final String toProxyConfigString() throws  {
    try {
      return (String)super.h.invoke(this, m20, (Object[])null);
    } catch (RuntimeException | Error var2) {
      throw var2;
    } catch (Throwable var3) {
      throw new UndeclaredThrowableException(var3);
    }
  }

  public final Advisor[] getAdvisors() throws  {
    try {
      return (Advisor[])super.h.invoke(this, m8, (Object[])null);
    } catch (RuntimeException | Error var2) {
      throw var2;
    } catch (Throwable var3) {
      throw new UndeclaredThrowableException(var3);
    }
  }

  public final boolean isPreFiltered() throws  {
    try {
      return (Boolean)super.h.invoke(this, m11, (Object[])null);
    } catch (RuntimeException | Error var2) {
      throw var2;
    } catch (Throwable var3) {
      throw new UndeclaredThrowableException(var3);
    }
  }

  static {
    try {
      m1 = Class.forName("java.lang.Object").getMethod("equals", Class.forName("java.lang.Object"));
      m15 = Class.forName("org.springframework.aop.framework.Advised").getMethod("addAdvisor", Class.forName("org.springframework.aop.Advisor"));
      m26 = Class.forName("org.springframework.aop.framework.Advised").getMethod("isExposeProxy");
      m22 = Class.forName("org.springframework.aop.framework.Advised").getMethod("isProxyTargetClass");
      m17 = Class.forName("org.springframework.aop.framework.Advised").getMethod("removeAdvisor", Integer.TYPE);
      m12 = Class.forName("org.springframework.aop.framework.Advised").getMethod("getProxiedInterfaces");
      m5 = Class.forName("org.springframework.aop.framework.Advised").getMethod("indexOf", Class.forName("org.springframework.aop.Advisor"));
      m21 = Class.forName("org.springframework.aop.framework.Advised").getMethod("getTargetSource");
      m10 = Class.forName("org.springframework.aop.framework.Advised").getMethod("addAdvice", Integer.TYPE, Class.forName("org.aopalliance.aop.Advice"));
      m9 = Class.forName("org.springframework.aop.framework.Advised").getMethod("addAdvice", Class.forName("org.aopalliance.aop.Advice"));
      m0 = Class.forName("java.lang.Object").getMethod("hashCode");
      m13 = Class.forName("org.springframework.aop.framework.Advised").getMethod("isInterfaceProxied", Class.forName("java.lang.Class"));
      m19 = Class.forName("org.springframework.aop.framework.Advised").getMethod("removeAdvice", Class.forName("org.aopalliance.aop.Advice"));
      m25 = Class.forName("org.springframework.aop.framework.Advised").getMethod("setExposeProxy", Boolean.TYPE);
      m23 = Class.forName("org.springframework.aop.framework.Advised").getMethod("setTargetSource", Class.forName("org.springframework.aop.TargetSource"));
      m2 = Class.forName("java.lang.Object").getMethod("toString");
      m27 = Class.forName("org.springframework.aop.framework.Advised").getMethod("getTargetClass");
      m14 = Class.forName("org.springframework.aop.framework.Advised").getMethod("addAdvisor", Integer.TYPE, Class.forName("org.springframework.aop.Advisor"));
      m28 = Class.forName("org.springframework.core.DecoratingProxy").getMethod("getDecoratedClass");
      m16 = Class.forName("org.springframework.aop.framework.Advised").getMethod("removeAdvisor", Class.forName("org.springframework.aop.Advisor"));
      m6 = Class.forName("org.springframework.aop.framework.Advised").getMethod("indexOf", Class.forName("org.aopalliance.aop.Advice"));
      m7 = Class.forName("org.springframework.aop.framework.Advised").getMethod("isFrozen");
      m18 = Class.forName("org.springframework.aop.framework.Advised").getMethod("replaceAdvisor", Class.forName("org.springframework.aop.Advisor"), Class.forName("org.springframework.aop.Advisor"));
      m24 = Class.forName("org.springframework.aop.framework.Advised").getMethod("setPreFiltered", Boolean.TYPE);
      m4 = Class.forName("com.xiaomi.mifi.instalment.api.server.IHello").getMethod("sayHello");
      m3 = Class.forName("org.springframework.beans.factory.InitializingBean").getMethod("afterPropertiesSet");
      m20 = Class.forName("org.springframework.aop.framework.Advised").getMethod("toProxyConfigString");
      m8 = Class.forName("org.springframework.aop.framework.Advised").getMethod("getAdvisors");
      m11 = Class.forName("org.springframework.aop.framework.Advised").getMethod("isPreFiltered");
    } catch (NoSuchMethodException var2) {
      throw new NoSuchMethodError(var2.getMessage());
    } catch (ClassNotFoundException var3) {
      throw new NoClassDefFoundError(var3.getMessage());
    }
  }
}

动态代理调用流程

注意，这里只能代理接口，生成的代理类继承 com.sun.Proxy 类，生成的代理方法来自于接口，而不是实现类，所以如果在实现类外面引用了实现类，而不是接口，这个类还被增强 了，那就会报错。提示
com.sun.Proxy 无法转换为需要的类型。就是因为这个原因。但是类内部的方法调用是不影响，属于内部调用（内部调用使用的是实现类对象的而不是代理对象，所以没有影响。
org.springframework.aop.framework.JdkDynamicAopProxy

final class JdkDynamicAopProxy implements AopProxy, InvocationHandler, Serializable {

// 代理类，会让所有的代理方法最终调用到这里，具体原因看上面生成的代理类
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
   MethodInvocation invocation;
   Object oldProxy = null;
   boolean setProxyContext = false;
   // 被代理的对象，testA
   TargetSource targetSource = this.advised.targetSource;
   Class<?> targetClass = null;
   Object target = null;

   try {
       // 之前检查做的标记，如果没有equal方法，并且正在调用则进行特殊处理，这里
      if (!this.equalsDefined && AopUtils.isEqualsMethod(method)) {
         // The target does not implement the equals(Object) method itself.
         // 这里的比较还是比较特殊的，可以看看，会对比很多东西，不会对比hashCode
         return equals(args[0]);
      }
       // 之前检查做的标记，如果没有hashCode 方法，并且正在调用则进行特殊处理
      else if (!this.hashCodeDefined && AopUtils.isHashCodeMethod(method)) {
         // 使用当前对象的hashCode,加上 被代理对象的hashCode保证其唯一性
         return hashCode();
      }
      else if (method.getDeclaringClass() == DecoratingProxy.class) {
         // There is only getDecoratedClass() declared -> dispatch to proxy config.
         // 默认实现，因为目前的代理类本身都不会实现这个方法，所有这里特殊处理
         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;
      }

      // May be null. Get as late as possible to minimize the time we "own" the target,
      // in case it comes from a pool.
      target = targetSource.getTarget();
      if (target != null) {
         targetClass = target.getClass();
      }

      // 这里获取的就是advice列表了，比如 AspectJAroundAdvice
      List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);
        // 没有需要代理的则直接调用被代理对象就好了
       if (chain.isEmpty()) {
         // 对于Strig ..args这种可变参数，进行兼容处理
         Object[] argsToUse = AopProxyUtils.adaptArgumentsIfNecessary(method, args);
          // 反射调用方法
         retVal = AopUtils.invokeJoinpointUsingReflection(target, method, argsToUse);
      }
      else {
         // 生成代理调用类，通过下标，根据filter这种链式调用，执行所有代理
         invocation = new ReflectiveMethodInvocation(proxy, target, method, args, targetClass, chain);
         // 开始执行
         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);
      }
   }
}

// 来自： org.springframework.aop.framework.ReflectiveMethodInvocation
@Override
public Object proceed() throws Throwable {
   // 最后执行，被代理对象的方法
   if (this.currentInterceptorIndex == this.interceptorsAndDynamicMethodMatchers.size() - 1) {
      return invokeJoinpoint();
   }
   // 从-1开始，所以先加+1，再使用
   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;
      if (dm.methodMatcher.matches(this.method, this.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 {
       // aroundAdvice这种都是实现了MethodInterceptor接口，走这里
       return ((MethodInterceptor) interceptorOrInterceptionAdvice).invoke(this);
   }
}

//  org.springframework.aop.aspectj.AspectJAroundAdvice
@Override
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);
}

// org.springframework.aop.aspectj.AbstractAspectJAdvice
// 调用切面增强器方法
protected Object invokeAdviceMethod(JoinPoint jp, JoinPointMatch jpMatch, Object returnValue, Throwable t)
      throws Throwable {
    // argBinding 进行参数的绑定
   return invokeAdviceMethodWithGivenArgs(argBinding(jp, jpMatch, returnValue, t));
}
protected Object invokeAdviceMethodWithGivenArgs(Object[] args) throws Throwable {
   Object[] actualArgs = args;
   if (this.aspectJAdviceMethod.getParameterTypes().length == 0) {
      actualArgs = null;
   }
   try {
      ReflectionUtils.makeAccessible(this.aspectJAdviceMethod);
      // this.aspectInstanceFactory.getAspectInstance() 通过前面创建的工厂类，获取增强器的额对象
      // 通过反射执行增强器的方法， 因为 around里面会继续调用 jointPoint.process()方法，所以这里不需要显示调用
      return this.aspectJAdviceMethod.invoke(this.aspectInstanceFactory.getAspectInstance(), actualArgs);
   }
   catch (IllegalArgumentException ex) {
      throw new AopInvocationException("Mismatch on arguments to advice method [" +
            this.aspectJAdviceMethod + "]; pointcut expression [" +
            this.pointcut.getPointcutExpression() + "]", ex);
   }
   catch (InvocationTargetException ex) {
      throw ex.getTargetException();
   }
}