SpringCache源码深度解析 spring ioc源码解读

缓存是我们常用的一种优化系统的方案。

无论是前端缓存还是应用层缓存或者数据库缓存，其本质都是将查询过的数据缓存下来，下次再次查询该数据的时候如果数据没有过期，则直接返回缓存中该数据即可，不再执行查询操作。

SpringCache是我们常用的一种应用层缓存方案，其一般应用在方法上，下面我们先来看下具体的使用方式，然后再从源码角度分析其实现方案

读者需要了解SpringCache的具体用法的话可以先参考其他文章。

1.SpringCache的使用

1）maven引入依赖

cache功能相关代码都在spring-context中，一般使用Spring的项目中都有该包，所以不用再单独引入

2）Service（业务处理类，代码参考网上文章，非原创，有改动）

// 接口类

package cache;
 
public interface IService {
	Account getAccountByName(String userName);
	void updateAccount(Account account);
}

// 实现类

public class AccountService implements IService{
	@Override
	@Cacheable(value = "accountCache") // 使用了一个缓存名叫 accountCache
	public Account getAccountByName(String userName) {
		// 方法内部实现不考虑缓存逻辑，直接实现业务
		System.out.println("real query account." + userName);
		return getFromDB(userName);
	}
 
	@Override
	@CacheEvict(value="accountCache",key="#account.getName()")
	public void updateAccount(Account account) {
		updateDB(account); 
	}
 
	@CacheEvict(value = "accountCache", allEntries = true)
	public void reload() {
	}
 
	private Account getFromDB(String acctName) {
		System.out.println("real querying db..." + acctName);
		return new Account(acctName);
	}
 
	private void updateDB(Account account) {
		System.out.println("real update db..." + account.getName());
	}
}

如上所示：在方法上加上@cacheable等注解即可

3）Spring-cache-anno.xml文件（用于定义bean）

<?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:cache="http://www.springframework.org/schema/cache"
	xmlns:p="http://www.springframework.org/schema/p"
	xsi:schemaLocation="http://www.springframework.org/schema/beans
	http://www.springframework.org/schema/beans/spring-beans.xsd
	http://www.springframework.org/schema/cache
	http://www.springframework.org/schema/cache/spring-cache.xsd">
 
	<!-- 添加driven -->
	<cache:annotation-driven />
	
	<bean id="accountServiceBean" class="cache.AccountService" />
	<!-- generic cache manager -->
	<bean id="cacheManager" class="org.springframework.cache.support.SimpleCacheManager">
		<property name="caches">
			<set>
				<bean
					class="org.springframework.cache.concurrent.ConcurrentMapCacheFactoryBean"
					p:name="accountCache" />
			</set>
		</property>
	</bean>
</beans>

使用默认的SimpleCacheManager

4）测试（测试缓存是否生效）

public class Test {
 
	public static void main(String[] args) {
		ApplicationContext context = new ClassPathXmlApplicationContext("spring-cache-anno.xml");
		IService s = context.getBean(IService.class);
		// 第一次查询，应该走数据库
		System.out.print("first query...");
		s.getAccountByName("somebody");
		// 第二次查询，应该不查数据库，直接返回缓存的值
		System.out.print("second query...");
		s.getAccountByName("somebody");
		System.out.println();
 }
}
 

//result：

first query...

real query account.somebody

real querying db...somebody

second query...

总结：根据结果可以看到，第二次查询的时候没有真正执行getFromDB()方法，而是从缓存中取的数据

2.写在源码分析之前

如果是我们来做的话，如何实现该功能？

基于我们对Spring的一贯理解，这应该是个代理，我们在获取IService的bean时候，应该获取的是个代理类，代理类执行业务方法，先去查询是否在缓存中有该数据，如果有则直接从缓存中获取，如果没有，则调用AccountService的方法

3.SpringCache源码结构分析

根据我们的示例可知，真正的内容都放在配置文件里了

配置文件中添加了一个driven（真正的功能应该在这里实现的）

<cache:annotation-driven />

下面是两个bean（accountServiceBean是我们需要的，需要将AccountService注入到容器中。

至于SimpleCacheManager暂时不知道其作用，只知道其实现了CacheManage接口，我们先暂时放一下）

 <bean id="accountServiceBean" class="cache.AccountService" />
	<!-- generic cache manager -->
	<bean id="cacheManager" class="org.springframework.cache.support.SimpleCacheManager">
		<property name="caches">
			<set>
				<bean
					class="org.springframework.cache.concurrent.ConcurrentMapCacheFactoryBean"
					p:name="accountCache" />
			</set>
		</property>
	</bean>

1）<cache:annotation-driven/>的分析

但凡这种注解，都有对应的解析器，从之前分析AOP功能的源码可知，解析器都实现了NamespaceHandlerSupport类，我们来获取下NamespaceHandlerSupport的实现类都有哪些

里面有一个叫做CacheNamespaceHandler的类，看名字就像这个，我们来看下这个类

2）CacheNamespaceHandler

public class CacheNamespaceHandler extends NamespaceHandlerSupport {
 
	static final String CACHE_MANAGER_ATTRIBUTE = "cache-manager";
 
	static final String DEFAULT_CACHE_MANAGER_BEAN_NAME = "cacheManager";
 ...
	@Override
	public void init() {
 // 主要是这句代码
		registerBeanDefinitionParser("annotation-driven", new AnnotationDrivenCacheBeanDefinitionParser());
		registerBeanDefinitionParser("advice", new CacheAdviceParser());
	}
}

Spring会默认调用其init()方法，annotation-driven对应的是AnnotationDrivenCacheBeanDefinitionParser解析器，我们来看下这个解析器的作用

 3）AnnotationDrivenCacheBeanDefinitionParser
	@Override
	public BeanDefinition parse(Element element, ParserContext parserContext) {
		String mode = element.getAttribute("mode");// mode默认为proxy
		if ("aspectj".equals(mode)) {
			// mode="aspectj"
			registerCacheAspect(element, parserContext);
		}
		else {
			// 直接调用该方法
			registerCacheAdvisor(element, parserContext);
		}
 
		return null;
	}
 
// registerCacheAdvisor()
	private void registerCacheAdvisor(Element element, ParserContext parserContext) {
 // 1.注册ProxyCreator类 在4）中详细分析
		AopNamespaceUtils.registerAutoProxyCreatorIfNecessary(parserContext, element);
 // 2.注册CacheAdvisor 在5）中详细分析
		SpringCachingConfigurer.registerCacheAdvisor(element, parserContext);
		if (jsr107Present && jcacheImplPresent) {
 // 默认不会调用
			JCacheCachingConfigurer.registerCacheAdvisor(element, parserContext);
		}
	}

4）AopNamespaceUtils.registerAutoProxyCreatorIfNecessary(parserContext, element)

	public static void registerAutoProxyCreatorIfNecessary(
			ParserContext parserContext, Element sourceElement) {
 // 重点在这里
		BeanDefinition beanDefinition = AopConfigUtils.registerAutoProxyCreatorIfNecessary(
				parserContext.getRegistry(), parserContext.extractSource(sourceElement));
		useClassProxyingIfNecessary(parserContext.getRegistry(), sourceElement);
		registerComponentIfNecessary(beanDefinition, parserContext);
	}
 
// AopConfigUtils.registerAutoProxyCreatorIfNecessary()
	public static BeanDefinition registerAutoProxyCreatorIfNecessary(BeanDefinitionRegistry registry, Object source) {
 // 重点在这里
		return registerOrEscalateApcAsRequired(InfrastructureAdvisorAutoProxyCreator.class, registry, source);
	}

可以看到，主要是为了将InfrastructureAdvisorAutoProxyCreator注册到容器中

5）SpringCachingConfigurer.registerCacheAdvisor(element, parserContext)

		private static void registerCacheAdvisor(Element element, ParserContext parserContext) {
			if (!parserContext.getRegistry().containsBeanDefinition(CacheManagementConfigUtils.CACHE_ADVISOR_BEAN_NAME)) {
				Object eleSource = parserContext.extractSource(element);
 
				// 1.注册AnnotationCacheOperationSource类到容器中
				RootBeanDefinition sourceDef = new RootBeanDefinition("org.springframework.cache.annotation.AnnotationCacheOperationSource");
				sourceDef.setSource(eleSource);
				sourceDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
				String sourceName = parserContext.getReaderContext().registerWithGeneratedName(sourceDef);
 
				// 2.注册CacheInterceptor类到容器中
				RootBeanDefinition interceptorDef = new RootBeanDefinition(CacheInterceptor.class);
				interceptorDef.setSource(eleSource);
				interceptorDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
				parseCacheResolution(element, interceptorDef, false);
				parseErrorHandler(element, interceptorDef);
				CacheNamespaceHandler.parseKeyGenerator(element, interceptorDef);
				interceptorDef.getPropertyValues().add("cacheOperationSources", new RuntimeBeanReference(sourceName));
				String interceptorName = parserContext.getReaderContext().registerWithGeneratedName(interceptorDef);
 
				// 3.注册BeanFactoryCacheOperationSourceAdvisor类到容器中，
				RootBeanDefinition advisorDef = new RootBeanDefinition(BeanFactoryCacheOperationSourceAdvisor.class);
				advisorDef.setSource(eleSource);
				advisorDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
 // 注意这里，将AnnotationCacheOperationSource和CacheInterceptor作为其属性注入进来
				advisorDef.getPropertyValues().add("cacheOperationSource", new RuntimeBeanReference(sourceName));
				advisorDef.getPropertyValues().add("adviceBeanName", interceptorName);
				if (element.hasAttribute("order")) {
					advisorDef.getPropertyValues().add("order", element.getAttribute("order"));
				}
 // 注意这句，将BeanFactoryCacheOperationSourceAdvisor类的注册名称设置为
 // org.springframework.cache.config.internalCacheAdvisor
 // 在下面会用到这个名称
				parserContext.getRegistry().registerBeanDefinition(CacheManagementConfigUtils.CACHE_ADVISOR_BEAN_NAME, advisorDef);
 
				...
			}
		}

总结：由以上分析可知，我们添加<cache:annotation-driven />注解，主要是将以下类注入进Spring容器

* InfrastructureAdvisorAutoProxyCreator

* AnnotationCacheOperationSource

* CacheInterceptor（主要的拦截功能都实现在这里）

* BeanFactoryCacheOperationSourceAdvisor（重点关注这个，这个类在创建代理的时候被使用）

我们暂时只知道加载driven注解的时候，只是将这四个类注入到Spring容器中，而这些类具体在做什么，我们也不知道，更不知道与我们的AccountService类有什么关联。这些我们先暂时放一下，先看下CacheInterceptor和InfrastructureAdvisorAutoProxyCreator的功能简介

4.CacheInterceptor功能简单分析

其代码结构如下

可知：

* 其实现了InitializingBean接口，则CacheInterceptor创建的时候会默认调用afterPropertiesSet()方法；

* 其实现了SmartInitializingSingleton接口，则CacheInterceptor创建的时候会默认调用afterSingletonsInstantiated()方法

* 其实现了MethodInterceptor接口，则在被其拦截的方法上，默认会调用其invoke()方法

有关于这些接口的作用，不太明白的同学可以先看下对应的文章了解其大致作用

1）初始化afterPropertiesSet()方法

// 只是做了校验，没有其他功能

 public void afterPropertiesSet() {
		Assert.state(getCacheOperationSource() != null, "The 'cacheOperationSources' property is required: " +
				"If there are no cacheable methods, then don't use a cache aspect.");
		Assert.state(getErrorHandler() != null, "The 'errorHandler' property is required");
	}

2）初始化afterSingletonsInstantiated()方法

	public void afterSingletonsInstantiated() {
		if (getCacheResolver() == null) {
			// Lazily initialize cache resolver via default cache manager...
			try {
 // 重点在这里
 // 从工厂类中获取CacheManager的实现类
 // 这里就与我们的Spring-cache-anno.xml配置文件中的创建的cacheManager 
 // bean关联起来了，在配置文件中创建的bean实现了接口CacheManager
 // 则会在这里被使用
				setCacheManager(this.beanFactory.getBean(CacheManager.class));
			}
			...
		}
		this.initialized = true;
	}
 
// setCacheManager()
	public void setCacheManager(CacheManager cacheManager) {
 // 	private CacheResolver cacheResolver;
		this.cacheResolver = new SimpleCacheResolver(cacheManager);
	}

3）invoke(）执行拦截方法（这个我们暂时先不分析，读者只需要知道这个拦截方法的存在即可）

	public Object invoke(final MethodInvocation invocation) throws Throwable {
		Method method = invocation.getMethod();
 
		CacheOperationInvoker aopAllianceInvoker = new CacheOperationInvoker() {
			@Override
			public Object invoke() {
				try {
					return invocation.proceed();
				}
				catch (Throwable ex) {
					throw new ThrowableWrapper(ex);
				}
			}
		};
 
		try {
			return execute(aopAllianceInvoker, invocation.getThis(), method, invocation.getArguments());
		}
		catch (CacheOperationInvoker.ThrowableWrapper th) {
			throw th.getOriginal();
		}
	}

总结4：

CacheInterceptor主要是一个方法拦截器，在初始化的时候将CacheManager的实现类（由用户自定义实现）添加进来；

invoke()方法，真正执行拦截的方法

5.InfrastructureAdvisorAutoProxyCreator功能分析

其代码结构如下：

可以看到，其实现了BeanPostProcessor接口，则Spring在创建bean的时候，会默认调用InfrastructureAdvisorAutoProxyCreator的postProcessAfterInitialization()方法，就是在这个方法中创建代理类的，下面我们来看下这个方法

1）AbstractAutoProxyCreator.postProcessAfterInitialization()

	public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
		if (bean != null) {
			Object cacheKey = getCacheKey(bean.getClass(), beanName);
			if (!this.earlyProxyReferences.contains(cacheKey)) {
 // 重要方法
				return wrapIfNecessary(bean, beanName, cacheKey);
			}
		}
		return bean;
	}
 
// wrapIfNecessary()
	protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) {
		...
 
		// 1.获取当前类的所有切面拦截类，在2）中详细分析
		Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);
 // 2.如果拦截类不为空，则需要创建当前类的代理类
		if (specificInterceptors != DO_NOT_PROXY) {
			this.advisedBeans.put(cacheKey, Boolean.TRUE);
 // 3.创建代理类，在3）中详细分析
			Object proxy = createProxy(
					bean.getClass(), beanName, specificInterceptors, new SingletonTargetSource(bean));
			this.proxyTypes.put(cacheKey, proxy.getClass());
			return proxy;
		}
 
		this.advisedBeans.put(cacheKey, Boolean.FALSE);
		return bean;
	}

以上逻辑类似于之前分析的AOP源码，读者也可以先看下 https://blog.csdn.net/qq_26323323/article/details/81012855

2）getAdvicesAndAdvisorsForBean()获取当前类的所有切面拦截器

本方法为抽象方法，实现由子类AbstractAdvisorAutoProxyCreator实现

	protected Object[] getAdvicesAndAdvisorsForBean(Class<?> beanClass, String beanName, TargetSource targetSource) {
		List<Advisor> advisors = findEligibleAdvisors(beanClass, beanName);//重点在这里
		if (advisors.isEmpty()) {
			return DO_NOT_PROXY;
		}
		return advisors.toArray();
	}
 
// findEligibleAdvisors()
	protected List<Advisor> findEligibleAdvisors(Class<?> beanClass, String beanName) {
 // 1.获取所有的Advisor
		List<Advisor> candidateAdvisors = findCandidateAdvisors();
 // 2.获取适合当前类的Advisor
		List<Advisor> eligibleAdvisors = findAdvisorsThatCanApply(candidateAdvisors, beanClass, beanName);
		extendAdvisors(eligibleAdvisors);
		if (!eligibleAdvisors.isEmpty()) {
			eligibleAdvisors = sortAdvisors(eligibleAdvisors);
		}
		return eligibleAdvisors;
	}
 * findCandidateAdvisors()获取所有的Advisor
// 	findCandidateAdvisors()
 protected List<Advisor> findCandidateAdvisors() {
		return this.advisorRetrievalHelper.findAdvisorBeans();
	}
 
 
//findAdvisorBeans()
	public List<Advisor> findAdvisorBeans() {
		// Determine list of advisor bean names, if not cached already.
		String[] advisorNames = null;
		synchronized (this) {
 // 1.cachedAdvisorBeanNames=org.springframework.cache.config.internalCacheAdvisor
			advisorNames = this.cachedAdvisorBeanNames;
			if (advisorNames == null) {
				// Do not initialize FactoryBeans here: We need to leave all regular beans
				// uninitialized to let the auto-proxy creator apply to them!
				advisorNames = BeanFactoryUtils.beanNamesForTypeIncludingAncestors(
						this.beanFactory, Advisor.class, true, false);
				this.cachedAdvisorBeanNames = advisorNames;
			}
		}
		if (advisorNames.length == 0) {
			return new LinkedList<Advisor>();
		}
 
		List<Advisor> advisors = new LinkedList<Advisor>();
		for (String name : advisorNames) {
			if (isEligibleBean(name)) {
				if (this.beanFactory.isCurrentlyInCreation(name)) {
					if (logger.isDebugEnabled()) {
						logger.debug("Skipping currently created advisor '" + name + "'");
					}
				}
				else {
					try {
 // 2.从工厂中获取CacheInterceptor对应的bean
 // 在上述代码 3节5）中，可知，
 // org.springframework.cache.config.internalCacheAdvisor这个名称对应bean为
 // BeanFactoryCacheOperationSourceAdvisor类，
						advisors.add(this.beanFactory.getBean(name, Advisor.class));
					}
					catch (BeanCreationException ex) {
						Throwable rootCause = ex.getMostSpecificCause();
						if (rootCause instanceof BeanCurrentlyInCreationException) {
							BeanCreationException bce = (BeanCreationException) rootCause;
							if (this.beanFactory.isCurrentlyInCreation(bce.getBeanName())) {
								if (logger.isDebugEnabled()) {
									logger.debug("Skipping advisor '" + name +
											"' with dependency on currently created bean: " + ex.getMessage());
								}
								// Ignore: indicates a reference back to the bean we're trying to advise.
								// We want to find advisors other than the currently created bean itself.
								continue;
							}
						}
						throw ex;
					}
				}
			}
		}
		return advisors;
	}

总结2）：适合当前类的Advisor最终为BeanFactoryCacheOperationSourceAdvisor类，也就是我们之前在分析<cache:annotation-driven/>中注册的BeanFactoryCacheOperationSourceAdvisor bean

3）createProxy( Class<?> beanClass, String beanName, Object[] specificInterceptors, TargetSource targetSource)

创建代理类

这里笔者就不再继续分析了，具体读者可参考 https://blog.csdn.net/qq_26323323/article/details/81012855 博文中创建proxy过程分析一节

总结5：InfrastructureAdvisorAutoProxyCreator的主要作用就是实现了BeanPostProcessor接口，那么Spring的每个bean在创建的过程中，都需要调用其postProcessAfterInitialization()方法，在这个方法中查询出所有适合当前类的Advisor，然后创建当前类的代理类，并将Advisor封装进来，在以后调用当前类的方法时使用

6.代理类invoke()方法调用

通过以上分析可知，Spring为我们创建的AccountService bean实际是一个关于AccountService的代理类，在调用AccountService的相关方法时，实际调用的是代理类的invoke()方法，下面我们就来分析下，invoke()方法被调用的过程，具体了解下我们的缓存是如何工作的

由于本例是JDKProxy创建的方式，而非CGLIBProxy的创建方式，所以AccountService的代理类为JdkDynamicAopProxy，下面看下其invoke()方法

1）JdkDynamicAopProxy.invoke()

	public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
		MethodInvocation invocation;
		Object oldProxy = null;
		boolean setProxyContext = false;
 
		TargetSource targetSource = this.advised.targetSource;
		Class<?> targetClass = null;
		Object target = null;
 
		try {
			...
			Object retVal;
 
			if (this.advised.exposeProxy) {
				// Make invocation available if necessary.
				oldProxy = AopContext.setCurrentProxy(proxy);
				setProxyContext = true;
			}
 
			target = targetSource.getTarget();
			if (target != null) {
				targetClass = target.getClass();
			}
 
			// 1.获取当前方法的拦截器链，也就是Advisor列表
 // 最终返回的是当前Advisor的拦截器MethodInterceptor列表
 // 在2）中详细分析
			List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);
 
 // 2.如果拦截器链为空，说明当前方法没有缓存注解，直接调用方法即可
			if (chain.isEmpty()) {
				Object[] argsToUse = AopProxyUtils.adaptArgumentsIfNecessary(method, args);
				retVal = AopUtils.invokeJoinpointUsingReflection(target, method, argsToUse);
			}
 // 3.说明当前方法有缓存注解，则需要先调用拦截器链的方法
			else {
				invocation = new ReflectiveMethodInvocation(proxy, target, method, args, targetClass, chain);
 // 真正的调用在这里
 // 在3）中详细分析
				retVal = invocation.proceed();
			}
 
			...
			return retVal;
		}
		...
	}

2）AdvisedSupport.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);获取当前方法的拦截器链

	public List<Object> getInterceptorsAndDynamicInterceptionAdvice(Method method, Class<?> targetClass) {
		MethodCacheKey cacheKey = new MethodCacheKey(method);
		List<Object> cached = this.methodCache.get(cacheKey);
		if (cached == null) {
 // 真正的实现在这里
			cached = this.advisorChainFactory.getInterceptorsAndDynamicInterceptionAdvice(
					this, method, targetClass);
			this.methodCache.put(cacheKey, cached);
		}
		return cached;
	}
 
//DefaultAdvisorChainFactory.getInterceptorsAndDynamicInterceptionAdvice()
	public List<Object> getInterceptorsAndDynamicInterceptionAdvice(
			Advised config, Method method, Class<?> targetClass) {
 
		// This is somewhat tricky... We have to process introductions first,
		// but we need to preserve order in the ultimate list.
		List<Object> interceptorList = new ArrayList<Object>(config.getAdvisors().length);
		Class<?> actualClass = (targetClass != null ? targetClass : method.getDeclaringClass());
		boolean hasIntroductions = hasMatchingIntroductions(config, actualClass);
		AdvisorAdapterRegistry registry = GlobalAdvisorAdapterRegistry.getInstance();
 
 // 1.遍历当前bean的所有Advisor
 // 就当前示例而言，只有一个Advisor，就是之前创建的BeanFactoryCacheOperationSourceAdvisor
		for (Advisor advisor : config.getAdvisors()) {
			if (advisor instanceof PointcutAdvisor) {
				// Add it conditionally.
				PointcutAdvisor pointcutAdvisor = (PointcutAdvisor) advisor;
				if (config.isPreFiltered() || pointcutAdvisor.getPointcut().getClassFilter().matches(actualClass)) {
 // 2.获取Advisor的Interceptor，也就是在分析<cache:annotation-driven />时
 // 被添加到BeanFactoryCacheOperationSourceAdvisor类的CacheInterceptor类
					MethodInterceptor[] interceptors = registry.getInterceptors(advisor);
					MethodMatcher mm = pointcutAdvisor.getPointcut().getMethodMatcher();
					if (MethodMatchers.matches(mm, method, actualClass, hasIntroductions)) {
						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;
	}

所以，拦截器链最终返回的是我们之前分析的CacheInterceptor类

3）ReflectiveMethodInvocation.proceed()拦截器链的调用分析

// InterceptedMethodInvocation.proceed() 
 public Object proceed() throws Throwable {
 try {
 // 主要就是遍历调用Interceptor的invoke方法
 return index == interceptors.length
 ? methodProxy.invokeSuper(proxy, arguments)
 : interceptors[index].invoke(
 new InterceptedMethodInvocation(proxy, methodProxy, arguments, index + 1));
 } catch (Throwable t) {
 pruneStacktrace(t);
 throw t;
 }
 }
 那我们看下CacheInterceptor.invoke()方法
	public Object invoke(final MethodInvocation invocation) throws Throwable {
		Method method = invocation.getMethod();
 
		CacheOperationInvoker aopAllianceInvoker = new CacheOperationInvoker() {
			@Override
			public Object invoke() {
				try {
					return invocation.proceed();
				}
				catch (Throwable ex) {
					throw new ThrowableWrapper(ex);
				}
			}
		};
 
		try {
 // 重点方法
			return execute(aopAllianceInvoker, invocation.getThis(), method, invocation.getArguments());
		}
		catch (CacheOperationInvoker.ThrowableWrapper th) {
			throw th.getOriginal();
		}
	}
 
//CacheAspectSupport.execute()
	protected Object execute(CacheOperationInvoker invoker, Object target, Method method, Object[] args) {
		// Check whether aspect is enabled (to cope with cases where the AJ is pulled in automatically)
		if (this.initialized) {
			Class<?> targetClass = getTargetClass(target);
 // 1.获取当前方法的缓存操作
			Collection<CacheOperation> operations = getCacheOperationSource().getCacheOperations(method, targetClass);
			if (!CollectionUtils.isEmpty(operations)) {
 // 2.执行缓存操作
				return execute(invoker, method, new CacheOperationContexts(operations, method, args, target, targetClass));
			}
		}
 
		return invoker.invoke();
	}
 * getCacheOperationSource().getCacheOperations(method, targetClass)获取当前方法的缓存操作
 默认实现类为AbstractFallbackCacheOperationSource
// AbstractFallbackCacheOperationSource.getCacheOperations(Method method, Class<?> targetClass)
	public Collection<CacheOperation> getCacheOperations(Method method, Class<?> targetClass) {
		if (method.getDeclaringClass() == Object.class) {
			return null;
		}
 
		Object cacheKey = getCacheKey(method, targetClass);
		Collection<CacheOperation> cached = this.attributeCache.get(cacheKey);
 
		if (cached != null) {
			return (cached != NULL_CACHING_ATTRIBUTE ? cached : null);
		}
		else {
			Collection<CacheOperation> cacheOps = computeCacheOperations(method, targetClass);
			if (cacheOps != null) {
				if (logger.isDebugEnabled()) {
					logger.debug("Adding cacheable method '" + method.getName() + "' with attribute: " + cacheOps);
				}
				this.attributeCache.put(cacheKey, cacheOps);
			}
			else {
				this.attributeCache.put(cacheKey, NULL_CACHING_ATTRIBUTE);
			}
			return cacheOps;
		}
	}
 * 执行execute()方法（关于操作缓存细节笔者不再详细分析，读者可自行分析）
	private Object execute(final CacheOperationInvoker invoker, Method method, CacheOperationContexts contexts) {
		// Special handling of synchronized invocation
		if (contexts.isSynchronized()) {
			CacheOperationContext context = contexts.get(CacheableOperation.class).iterator().next();
			if (isConditionPassing(context, CacheOperationExpressionEvaluator.NO_RESULT)) {
				Object key = generateKey(context, CacheOperationExpressionEvaluator.NO_RESULT);
				Cache cache = context.getCaches().iterator().next();
				try {
					return wrapCacheValue(method, cache.get(key, new Callable<Object>() {
						@Override
						public Object call() throws Exception {
							return unwrapReturnValue(invokeOperation(invoker));
						}
					}));
				}
				catch (Cache.ValueRetrievalException ex) {
					// The invoker wraps any Throwable in a ThrowableWrapper instance so we
					// can just make sure that one bubbles up the stack.
					throw (CacheOperationInvoker.ThrowableWrapper) ex.getCause();
				}
			}
			else {
				// No caching required, only call the underlying method
				return invokeOperation(invoker);
			}
		}
 
 
		// Process any early evictions
		processCacheEvicts(contexts.get(CacheEvictOperation.class), true,
				CacheOperationExpressionEvaluator.NO_RESULT);
 
		// Check if we have a cached item matching the conditions
		Cache.ValueWrapper cacheHit = findCachedItem(contexts.get(CacheableOperation.class));
 
		// Collect puts from any @Cacheable miss, if no cached item is found
		List<CachePutRequest> cachePutRequests = new LinkedList<CachePutRequest>();
		if (cacheHit == null) {
			collectPutRequests(contexts.get(CacheableOperation.class),
					CacheOperationExpressionEvaluator.NO_RESULT, cachePutRequests);
		}
 
		Object cacheValue;
		Object returnValue;
 
		if (cacheHit != null && cachePutRequests.isEmpty() && !hasCachePut(contexts)) {
			// If there are no put requests, just use the cache hit
			cacheValue = cacheHit.get();
			returnValue = wrapCacheValue(method, cacheValue);
		}
		else {
			// Invoke the method if we don't have a cache hit
			returnValue = invokeOperation(invoker);
			cacheValue = unwrapReturnValue(returnValue);
		}
 
		// Collect any explicit @CachePuts
		collectPutRequests(contexts.get(CachePutOperation.class), cacheValue, cachePutRequests);
 
		// Process any collected put requests, either from @CachePut or a @Cacheable miss
		for (CachePutRequest cachePutRequest : cachePutRequests) {
			cachePutRequest.apply(cacheValue);
		}
 
		// Process any late evictions
		processCacheEvicts(contexts.get(CacheEvictOperation.class), false, cacheValue);
 
		return returnValue;
	}

总结：

缓存功能的实现实际也是通过Spring代理来实现的。生成当前类的代理类，调用代理类的invoke()方法，在invoke()方法中调用CacheInterceptor拦截器的execute()方法，拦截器会使用缓存器（本例中的SimpleCacheManager）来进行具体方法实现。

重要操作流程如下：

1）解析<cache:annotation-driven />，将InfrastructureAdvisorAutoProxyCreator注入到Spring容器中，该类的作用是在Spring创建bean实例的时候，会执行其postProcessAfterInitialization()方法，生成bean实例的代理类

2）解析<cache:annotation-driven />，将BeanFactoryCacheOperationSourceAdvisor类注入到Spring容器中，该类的主要作用是作为一个Advisor添加到上述代理类中

3）BeanFactoryCacheOperationSourceAdvisor类拥有对CacheInterceptor的依赖，CacheInterceptor作为一个方法拦截器，负责对缓存方法的拦截，

4）当前类方法调用被拦截到CacheInterceptor后，CacheInterceptor会调用我们在配置文件中配置的CacheManager实现（也就是本例中的SimpleCacheManager），来真正实现缓存功能