準備工作

本文分析Spring的AOP模塊的整體流程，分析過程需要使用一個簡單的demo工程來啟動Spring。

<code>https://github.com/cjinjun/spring-framework-demo/<code>

寫一個簡單的接口和實現類，跟IOC源碼解析那幾篇文章用的同一個工程，

<code>public interface IOCService {
    public String helloIoc();
}

public class IOCServiceImpl implements IOCService {
    public String helloIoc() {
        return "Hello,IOC";
    }
}/<code>

增加bean的配置類，以及啟動AOP

<code>@EnableAspectJAutoProxy
@Configuration
public class AnnotationConfig {
    @Bean
    public IOCService iocService(){
        return new IOCServiceImpl();
    }
}/<code>

創建切點

<code>@Aspect
@Component
public class AspectJTest {

    @Pointcut("execution(public * com.jinjun.demo.ioc.service..IOCService.helloIoc(..))")
    public void testAOP(){}

    @Before("testAOP()")
    public void before(){ 

        System.out.println("before AOP...");
    }

    @After("testAOP()")
    public void after(){
        System.out.println("after AOP...");
    }

    @Around("testAOP()")
    public Object around(ProceedingJoinPoint p){
        System.out.println("around before AOP...");
        Object o = null;
        try {
            o = p.proceed();
        } catch (Throwable e) {
            e.printStackTrace();
        }
        System.out.println("around after AOP...");
        return o;
    }
}/<code>

啟動spring

<code>public class AnnotationIOCDemo {
    public static void main (String args[]){
        ApplicationContext context = new AnnotationConfigApplicationContext("cn.shiyujun.config");
        IOCService iocService=context.getBean(IOCService.class);
        System.out.println(iocService.@EnableAspectJAutoProxy註解());
    }
}/<code>

代碼部分到此，然後首先看一下

@EnableAspectJAutoProxy註解

為了開啟AOP功能，使用了一個@EnableAspectJAutoProxy註解，進入這個註解可以查看到這個註解的2個屬性，相信大家都已經很熟悉了，就不相信的說明了。除此之外可以看到這個註解使用@Import註解引入了一個配置類

@Import註解：可以引入一個類，將這個類注入到Spring IOC容器中被當前Spring管理

<code>@Import(AspectJAutoProxyRegistrar.class)
public @interface EnableAspectJAutoProxy {
    //proxyTargetClass屬性，默認false，嘗試採用JDK動態代理織入增強(如果當前類沒有實現接口則還是會使用CGLIB)；如果設為true，則強制採用CGLIB動態代理織入增強
    boolean proxyTargetClass() default false;
    //通過aop框架暴露該代理對象，aopContext能夠訪問。為了解決類內部方法之間調用時無法增強的問題
    boolean exposeProxy() default false;
}/<code>

看一下這個配置類的操作

<code>
class AspectJAutoProxyRegistrar implements ImportBeanDefinitionRegistrar {
    AspectJAutoProxyRegistrar() {
    }

    public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
               //註冊一個AOP代理實現的Bean，往下看          AopConfigUtils.registerAspectJAnnotationAutoProxyCreatorIfNecessary(registry);
        AnnotationAttributes enableAspectJAutoProxy = AnnotationConfigUtils.attributesFor(importingClassMetadata, EnableAspectJAutoProxy.class);
        if (enableAspectJAutoProxy != null) {
            if (enableAspectJAutoProxy.getBoolean("proxyTargetClass")) {
                AopConfigUtils.forceAutoProxyCreatorToUseClassProxying(registry);
            }

            if (enableAspectJAutoProxy.getBoolean("exposeProxy")) {
                AopConfigUtils.forceAutoProxyCreatorToExposeProxy(registry);
            }
        }

    }
}/<code>

registerAspectJAnnotationAutoProxyCreatorIfNecessary方法的主要功能是註冊或者升級AnnotationAwareAspectJAutoProxyCreator類，這個類在AOP中非常的重要，它的主要功能就是根據@Point註解定義的切點來自動代理與表達式匹配的類。下面看一個這個實現的邏輯

<code>private static BeanDefinition registerOrEscalateApcAsRequired(Class> cls, BeanDefinitionRegistry registry, @Nullable Object source) {
        Assert.notNull(registry, "BeanDefinitionRegistry must not be null"); //如果已存在這個bean
        if (registry.containsBeanDefinition("org.springframework.aop.config.internalAutoProxyCreator")) {
            BeanDefinition apcDefinition = registry.getBeanDefinition("org.springframework.aop.config.internalAutoProxyCreator");
            //判斷優先級，如果優先級較高則替換原先的bean
            if (!cls.getName().equals(apcDefinition.getBeanClassName())) {
                int currentPriority = findPriorityForClass(apcDefinition.getBeanClassName());
                int requiredPriority = findPriorityForClass(cls);
                if (currentPriority < requiredPriority) {
                    apcDefinition.setBeanClassName(cls.getName());
                }
            }

            return null;
        } else {
            //註冊AnnotationAwareAspectJAutoProxyCreator到容器中，此類負責基於註解的AOP動態代理實現
            RootBeanDefinition beanDefinition = new RootBeanDefinition(cls);
            beanDefinition.setSource(source);
            beanDefinition.getPropertyValues().add("order", -2147483648);
            beanDefinition.setRole(2);
            registry.registerBeanDefinition("org.springframework.aop.config.internalAutoProxyCreator", beanDefinition);
            return beanDefinition;
        }
    }/<code>

註冊的AnnotationAwareAspectJAutoProxyCreator這個類間接實現了BeanPostProcessor接口。還記得我們之前在對SpringIOC的源碼進行解析時提到過，Spring在實例化Bean的前後會分別調用方法postProcessBeforeInstantiation和postProcessAfterInstantiation而AOP的整體邏輯就是通過這兩個方法來實現的

postProcessBeforeInstantiation

首先看一下這個postProcessBeforeInstantiation方法，它是在bean實例化之前調用的，主要是針對切面類。這個方法不在AnnotationAwareAspectJAutoProxyCreator這個類中，而是在其父類AbstractAutoProxyCreator中

<code>public Object postProcessBeforeInstantiation(Class> beanClass, String beanName) throws BeansException {
    Object cacheKey = getCacheKey(beanClass, beanName); 


    if (!StringUtils.hasLength(beanName) || !this.targetSourcedBeans.contains(beanName)) {
      if (this.advisedBeans.containsKey(cacheKey)) {
        return null;
      }
            //加載所有增強
      if (isInfrastructureClass(beanClass) || shouldSkip(beanClass, beanName)) {
        this.advisedBeans.put(cacheKey, Boolean.FALSE);
        return null;
      }
    }

    TargetSource targetSource = getCustomTargetSource(beanClass, beanName);
    if (targetSource != null) {
      if (StringUtils.hasLength(beanName)) {
        this.targetSourcedBeans.add(beanName);
      }
      Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(beanClass, beanName, targetSource);
      Object proxy = createProxy(beanClass, beanName, specificInterceptors, targetSource);
      this.proxyTypes.put(cacheKey, proxy.getClass());
      return proxy;
    }

    return null;
  }/<code>

加載增強

上方代碼中最重要的一個方法就是shouldSkip方法了，被AspectJAwareAdvisorAutoProxyCreator所重載

<code>
protected boolean shouldSkip(Class> beanClass, String beanName) {
  
    //查找所有標識了@Aspect註解的類，這裡是重點，接著往下看
    List<advisor> candidateAdvisors = findCandidateAdvisors();
    for (Advisor advisor : candidateAdvisors) {
        if (advisor instanceof AspectJPointcutAdvisor) {
            if (((AbstractAspectJAdvice) advisor.getAdvice()).getAspectName().equals(beanName)) {
                return true;
            }
        }
    }
    return super.shouldSkip(beanClass, beanName);
    }
 


    protected List<advisor> findCandidateAdvisors() {
        return this.advisorRetrievalHelper.findAdvisorBeans();
    }
    
    protected List<advisor> findCandidateAdvisors() {
        List<advisor> advisors = super.findCandidateAdvisors();
        //buildAspectJAdvisors是重點
           advisors.addAll(this.aspectJAdvisorsBuilder.buildAspectJAdvisors());
        return advisors;
    }/<advisor>/<advisor>/<advisor>/<advisor>/<code>

<code>
public List<advisor> buildAspectJAdvisors() {
//所有Aspect類的名稱集合
    List<string> aspectNames = this.aspectBeanNames;
    if (aspectNames == null) {
        synchronized (this) {
            aspectNames = this.aspectBeanNames;
            //這個雙重檢查是不是在學習安全的單例模式的時候見過
            if (aspectNames == null) {
                List<advisor> advisors = new LinkedList<advisor>();
                aspectNames = new LinkedList<string>();
                //獲取所有Bean名稱
                String[] beanNames = BeanFactoryUtils.beanNamesForTypeIncludingAncestors(
                        this.beanFactory, Object.class, true, false);
                for (String beanName : beanNames) {
                    //判斷是否符合條件，比如說有時會排除一些類，不讓這些類注入進Spring
                    if (!isEligibleBean(beanName)) {
                        continue;
                    }
           
                    Class> beanType = this.beanFactory.getType(beanName);
                    if (beanType == null) {
                        continue;
                    }
                    //判斷Bean的Class上是否標識@Aspect註解
                    if (this.advisorFactory.isAspect(beanType)) {
                        aspectNames.add(beanName);
                        AspectMetadata amd = new AspectMetadata(beanType, beanName);
                        if (amd.getAjType().getPerClause().getKind() == PerClauseKind.SINGLETON) {
                            MetadataAwareAspectInstanceFactory factory = 

                                    new BeanFactoryAspectInstanceFactory(this.beanFactory, beanName);
                            //下一步說，重點的重點
                            List<advisor> classAdvisors = this.advisorFactory.getAdvisors(factory);
                            if (this.beanFactory.isSingleton(beanName)) {
                                //將解析的Bean名稱及類上的增強緩存起來,每個Bean只解析一次
                                this.advisorsCache.put(beanName, classAdvisors);
                            }
                            else {
                                this.aspectFactoryCache.put(beanName, factory);
                            }
                            advisors.addAll(classAdvisors);
                        }
                        else {
                            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<advisor> advisors = new LinkedList<advisor>();
    for (String aspectName : aspectNames) {
        //從緩存中獲取當前Bean的切面實例，如果不為空，則指明當前Bean的Class標識了@Aspect，且有切面方法
        List<advisor> cachedAdvisors = this.advisorsCache.get(aspectName);
        if (cachedAdvisors != null) {
            advisors.addAll(cachedAdvisors);
        }
        else {
            MetadataAwareAspectInstanceFactory factory = this.aspectFactoryCache.get(aspectName);
            advisors.addAll(this.advisorFactory.getAdvisors(factory)); 

        }
    }
    return advisors;
}/<advisor>/<advisor>/<advisor>/<advisor>/<string>/<advisor>/<advisor>/<string>/<advisor>/<code>

生成增強

advisorFactory.getAdvisors方法會從@Aspect標識的類上獲取@Before，@Pointcut等註解的信息及其標識的方法的信息，生成增強

<code>public List<advisor> getAdvisors(MetadataAwareAspectInstanceFactory aspectInstanceFactory) {
    Class> aspectClass = aspectInstanceFactory.getAspectMetadata().getAspectClass();
    String aspectName = aspectInstanceFactory.getAspectMetadata().getAspectName();
    //校驗類的合法性相關
    validate(aspectClass);

    MetadataAwareAspectInstanceFactory lazySingletonAspectInstanceFactory =
            new LazySingletonAspectInstanceFactoryDecorator(aspectInstanceFactory);

    List<advisor> advisors = new LinkedList<advisor>();
    //獲取這個類所有的增強方法
    for (Method method : getAdvisorMethods(aspectClass)) {
        //生成增強實例
        Advisor advisor = getAdvisor(method, lazySingletonAspectInstanceFactory, advisors.size(), aspectName);
        if (advisor != null) {
            advisors.add(advisor);
        }
    }

    if (!advisors.isEmpty() && lazySingletonAspectInstanceFactory.getAspectMetadata().isLazilyInstantiated()) {
        Advisor instantiationAdvisor = new SyntheticInstantiationAdvisor(lazySingletonAspectInstanceFactory);
        advisors.add(0, instantiationAdvisor);
    }

    for (Field field : aspectClass.getDeclaredFields()) {
        Advisor advisor = getDeclareParentsAdvisor(field);
        if (advisor != null) {
            advisors.add(advisor);
        }
    }

    return advisors;
}

//獲取類的的方法 

private List<method> getAdvisorMethods(Class> aspectClass) {
    final List<method> methods = new LinkedList<method>();
    ReflectionUtils.doWithMethods(aspectClass, new ReflectionUtils.MethodCallback() {
        @Override
        public void doWith(Method method) throws IllegalArgumentException {
                //在@Aspect標識的類內部排除@Pointcut標識之外的所有方法，得到的方法集合包括繼承自父類的方法，包括繼承自Object的方法
            if (AnnotationUtils.getAnnotation(method, Pointcut.class) == null) {
                methods.add(method);
            }
        }
    });
    //對得到的所有方法排序，
    //如果方法標識了切面註解，則按@Around, @Before, @After, @AfterReturning, @AfterThrowing的順序排序
    //如果沒有標識這些註解，則按方法名稱的字符串排序,
    //有註解的方法排在無註解的方法之前
    //最後的排序應該是這樣的Around.class, Before.class, After.class, AfterReturning.class, AfterThrowing.class。。。
    Collections.sort(methods, METHOD_COMPARATOR);
    return methods;
}/<method>/<method>/<method>/<advisor>/<advisor>/<advisor>/<code>

調用生成增強實例的方法

<code>public Advisor getAdvisor(Method candidateAdviceMethod, MetadataAwareAspectInstanceFactory aspectInstanceFactory,
        int declarationOrderInAspect, String aspectName) {
    //再次校驗類的合法性
    validate(aspectInstanceFactory.getAspectMetadata().getAspectClass());
    //切點表達式的包裝類裡面包含這些東西：execution(public * cn.shiyujun.service.IOCService.hollo(..))
    AspectJExpressionPointcut expressionPointcut = getPointcut(
            candidateAdviceMethod, aspectInstanceFactory.getAspectMetadata().getAspectClass());
    if (expressionPointcut == null) {
        return null;
    }
    //根據方法、切點、AOP實例工廠、類名、序號生成切面實例，詳細代碼往下看 

    return new InstantiationModelAwarePointcutAdvisorImpl(expressionPointcut, candidateAdviceMethod,
            this, aspectInstanceFactory, declarationOrderInAspect, aspectName);
}

private AspectJExpressionPointcut getPointcut(Method candidateAdviceMethod, Class> candidateAspectClass) {
    //查詢方法上的切面註解，根據註解生成相應類型的AspectJAnnotation,在調用AspectJAnnotation的構造函數的同時
    //根據註解value或pointcut屬性得到切點表達式，有argNames則設置參數名稱
    AspectJAnnotation> aspectJAnnotation =
            AbstractAspectJAdvisorFactory.findAspectJAnnotationOnMethod(candidateAdviceMethod);
    //過濾那些不含@Before, @Around, @After, @AfterReturning, @AfterThrowing註解的方法
    if (aspectJAnnotation == null) {
        return null;
    }
    //生成帶表達式的切面切入點，設置其切入點表達式
    AspectJExpressionPointcut ajexp =
            new AspectJExpressionPointcut(candidateAspectClass, new String[0], new Class>[0]);
    ajexp.setExpression(aspectJAnnotation.getPointcutExpression());
    ajexp.setBeanFactory(this.beanFactory);
    return ajexp;
}/<code>

InstantiationModelAwarePointcutAdvisorImpl的構造方法

<code>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;

    if (aspectInstanceFactory.getAspectMetadata().isLazilyInstantiated()) {
      Pointcut preInstantiationPointcut = Pointcuts.union(
          aspectInstanceFactory.getAspectMetadata().getPerClausePointcut(), this.declaredPointcut);
 

      this.pointcut = new PerTargetInstantiationModelPointcut(
          this.declaredPointcut, preInstantiationPointcut, aspectInstanceFactory);
      this.lazy = true;
    }
    else {
      this.pointcut = this.declaredPointcut;
      this.lazy = false;
            //重點在這裡
      this.instantiatedAdvice = instantiateAdvice(this.declaredPointcut);
    }
  }
    
    private Advice instantiateAdvice(AspectJExpressionPointcut pointcut) {
    //再往下看
    Advice advice = this.aspectJAdvisorFactory.getAdvice(this.aspectJAdviceMethod, pointcut,
        this.aspectInstanceFactory, this.declarationOrder, this.aspectName);
    return (advice != null ? advice : EMPTY_ADVICE);
  }/<code>

生產增強

<code>public class ReflectiveAspectJAdvisorFactory extends AbstractAspectJAdvisorFactory implements Serializable {

    public Advice getAdvice(Method candidateAdviceMethod, AspectJExpressionPointcut expressionPointcut,
            MetadataAwareAspectInstanceFactory aspectInstanceFactory, int declarationOrder, String aspectName) {

        Class> candidateAspectClass = aspectInstanceFactory.getAspectMetadata().getAspectClass();
        //又是一次校驗
        validate(candidateAspectClass);

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

        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;
        //根據註解類型生成不同的通知實例 

        switch (aspectJAnnotation.getAnnotationType()) {
            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;
            case AtAround:
                springAdvice = new AspectJAroundAdvice(
                        candidateAdviceMethod, expressionPointcut, aspectInstanceFactory);
                break;
            case AtPointcut:
                if (logger.isDebugEnabled()) {
                    logger.debug("Processing pointcut '" + candidateAdviceMethod.getName() + "'");
                }
                return null;
            default:
                throw new UnsupportedOperationException(
                        "Unsupported advice type on method: " + candidateAdviceMethod);
        }

        //設置通知方法所屬的類
        springAdvice.setAspectName(aspectName);
        //設置通知的序號,同一個類中有多個切面註解標識的方法時,按上方說的排序規則來排序，
        //其序號就是此方法在列表中的序號，第一個就是0
        springAdvice.setDeclarationOrder(declarationOrder); 

        //獲取通知方法的所有參數
        String[] argNames = this.parameterNameDiscoverer.getParameterNames(candidateAdviceMethod);
        //將通知方法上的參數設置到通知中
        if (argNames != null) {
            springAdvice.setArgumentNamesFromStringArray(argNames);
        }
        //計算參數綁定工作，此方法詳解請接著往下看
        springAdvice.calculateArgumentBindings();
        return springAdvice;
    }
}/<code>

校驗方法參數並綁定

<code>public synchronized final void calculateArgumentBindings() {
    if (this.argumentsIntrospected || this.parameterTypes.length == 0) {
        return;
    }

    int numUnboundArgs = this.parameterTypes.length;
    Class>[] parameterTypes = this.aspectJAdviceMethod.getParameterTypes();
    //切面註解標識的方法第一個參數要求是JoinPoint,或StaticPart，若是@Around註解則也可以是ProceedingJoinPoint
    if (maybeBindJoinPoint(parameterTypes[0]) || maybeBindProceedingJoinPoint(parameterTypes[0])) {
        numUnboundArgs--;
    }
    else if (maybeBindJoinPointStaticPart(parameterTypes[0])) {
        numUnboundArgs--;
    }

    if (numUnboundArgs > 0) {
    //綁定屬性
        bindArgumentsByName(numUnboundArgs);
    }

    this.argumentsIntrospected = true;
}
private void bindArgumentsByName(int numArgumentsExpectingToBind) {
    if (this.argumentNames == null) { //獲取方法參數的名稱
        this.argumentNames = createParameterNameDiscoverer().getParameterNames(this.aspectJAdviceMethod);
    }
    if (this.argumentNames != null) { 

        // 往下看
        bindExplicitArguments(numArgumentsExpectingToBind);
    }
    else {
        throw new IllegalStateException("Advice method [" + this.aspectJAdviceMethod.getName() + "] " +
                "requires " + numArgumentsExpectingToBind + " arguments to be bound by name, but " +
                "the argument names were not specified and could not be discovered.");
    }
}

private void bindExplicitArguments(int numArgumentsLeftToBind) {
    //此屬性用來存儲方法未綁定的參數名稱，及參數的序號
    this.argumentBindings = new HashMap<string>();

    int numExpectedArgumentNames = this.aspectJAdviceMethod.getParameterTypes().length;
    if (this.argumentNames.length != numExpectedArgumentNames) {
        throw new IllegalStateException("Expecting to find " + numExpectedArgumentNames +
                " arguments to bind by name in advice, but actually found " +
                this.argumentNames.length + " arguments.");
    }

    // So we match in number...,argumentIndexOffset代表第一個未綁定參數的順序 
    int argumentIndexOffset = this.parameterTypes.length - numArgumentsLeftToBind;
    for (int i = argumentIndexOffset; i < this.argumentNames.length; i++) {
        //存儲未綁定的參數名稱及其順序的映射關係
        this.argumentBindings.put(this.argumentNames[i], i);
    }

    // Check that returning and throwing were in the argument names list if
    // specified, and find the discovered argument types.
    //如果是@AfterReturning註解的returningName 有值，驗證，解析，同時得到定義返回值的類型
    if (this.returningName != null) {
        if (!this.argumentBindings.containsKey(this.returningName)) {
            throw new IllegalStateException("Returning argument name '" + this.returningName +
                    "' was not bound in advice arguments");
        }
        else {
            Integer index = this.argumentBindings.get(this.returningName);
            this.discoveredReturningType = this.aspectJAdviceMethod.getParameterTypes()[index];
            this.discoveredReturningGenericType = this.aspectJAdviceMethod.getGenericParameterTypes()[index];
        }
    } 

    //如果是@AfterThrowing註解的throwingName 有值，驗證，解析，同時得到拋出異常的類型
    if (this.throwingName != null) {
        if (!this.argumentBindings.containsKey(this.throwingName)) {
            throw new IllegalStateException("Throwing argument name '" + this.throwingName +
                    "' was not bound in advice arguments");
        }
        else {
            Integer index = this.argumentBindings.get(this.throwingName);
            this.discoveredThrowingType = this.aspectJAdviceMethod.getParameterTypes()[index];
        }
    }

    // configure the pointcut expression accordingly.
    configurePointcutParameters(argumentIndexOffset);
}

private void configurePointcutParameters(int argumentIndexOffset) {
    int numParametersToRemove = argumentIndexOffset;
    if (this.returningName != null) {
        numParametersToRemove++;
    }
    if (this.throwingName != null) {
        numParametersToRemove++;
    }
    String[] pointcutParameterNames = new String[this.argumentNames.length - numParametersToRemove];
    Class>[] pointcutParameterTypes = new Class>[pointcutParameterNames.length];
    Class>[] methodParameterTypes = this.aspectJAdviceMethod.getParameterTypes();

    int index = 0;
    for (int i = 0; i < this.argumentNames.length; i++) {
        if (i < argumentIndexOffset) {
            continue;
        }
        if (this.argumentNames[i].equals(this.returningName) ||
            this.argumentNames[i].equals(this.throwingName)) {
            continue;
        }
        pointcutParameterNames[index] = this.argumentNames[i];
        pointcutParameterTypes[index] = methodParameterTypes[i];
        index++;
    }
    //剩餘的未綁定的參數會賦值給AspectJExpressionPointcut(表達式形式的切入點)的屬性，以備後續使用
    this.pointcut.setParameterNames(pointcutParameterNames);
    this.pointcut.setParameterTypes(pointcutParameterTypes);
}/<string>/<code> 

篇幅原因，本文到此結束，期待下集，下集主要說明postProcessAfterInitialization 及Aop 剩下的實現邏輯

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關鍵字: 源碼 beanName candidateAdviceMethod