概述
怎么使用AOP
我们在使用AOP的时候，大致分为三步
- 1）、将业务逻辑组件和切面类都加入到容器中；告诉Spring哪个是切面类（@Aspect）
- 2）、在切面类上的每一个通知方法上标注通知注解，告诉Spring何时何地运行（切入点表达式）
- 3）、开启基于注解的aop模式；@EnableAspectJAutoProxy（如果是spring boot项目，则引入AOP的stater但还是要引入@EnableAspectJAutoProxy注解）
那么我们就分析一下@EnableAspectJAutoProxy注解的作用
@EnableAspectJAutoProxy的作用
可以看到这个注解使用@Import引入了AspectJAutoProxyRegistrar类
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Import(AspectJAutoProxyRegistrar.class)
public @interface EnableAspectJAutoProxy {
看一下AspectJAutoProxyRegistrar
class AspectJAutoProxyRegistrar implements ImportBeanDefinitionRegistrar {
/**
* Register, escalate, and configure the AspectJ auto proxy creator based on the value
* of the @{@link EnableAspectJAutoProxy#proxyTargetClass()} attribute on the importing
* {@code @Configuration} class.
*/
@Override
public void registerBeanDefinitions(
AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
AopConfigUtils.registerAspectJAnnotationAutoProxyCreatorIfNecessary(registry);
AnnotationAttributes enableAspectJAutoProxy =
AnnotationConfigUtils.attributesFor(importingClassMetadata, EnableAspectJAutoProxy.class);
if (enableAspectJAutoProxy.getBoolean("proxyTargetClass")) {
AopConfigUtils.forceAutoProxyCreatorToUseClassProxying(registry);
}
if (enableAspectJAutoProxy.getBoolean("exposeProxy")) {
AopConfigUtils.forceAutoProxyCreatorToExposeProxy(registry);
}
}
}这个来实现了ImportBeanDefinitionRegistrar接口，会调用registerBeanDefinitions方法往容器中注册一个组件
spring （一）注册组件，那么我们跟踪registerAspectJAnnotationAutoProxyCreatorIfNecessary这个方法看看到底做了什么，发现会使用AopConfigUtils来注册或者升级一个给容器中注册一个AnnotationAwareAspectJAutoProxyCreator；
public static BeanDefinition registerAspectJAnnotationAutoProxyCreatorIfNecessary(BeanDefinitionRegistry registry, Object source) {
return registerOrEscalateApcAsRequired(AnnotationAwareAspectJAutoProxyCreator.class, registry, source);
}
private static BeanDefinition registerOrEscalateApcAsRequired(Class<?> cls, BeanDefinitionRegistry registry, Object source) {
Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
if (registry.containsBeanDefinition(AUTO_PROXY_CREATOR_BEAN_NAME)) {
BeanDefinition apcDefinition = registry.getBeanDefinition(AUTO_PROXY_CREATOR_BEAN_NAME);
if (!cls.getName().equals(apcDefinition.getBeanClassName())) {
int currentPriority = findPriorityForClass(apcDefinition.getBeanClassName());
int requiredPriority = findPriorityForClass(cls);
if (currentPriority < requiredPriority) {
apcDefinition.setBeanClassName(cls.getName());
}
}
return null;
}
RootBeanDefinition beanDefinition = new RootBeanDefinition(cls);
beanDefinition.setSource(source);
beanDefinition.getPropertyValues().add("order", Ordered.HIGHEST_PRECEDENCE);
beanDefinition.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
registry.registerBeanDefinition(AUTO_PROXY_CREATOR_BEAN_NAME, beanDefinition);
return beanDefinition;
}既然注册了一个AnnotationAwareAspectJAutoProxyCreator类型的bean到容器，那么接下来我们查看一下
AnnotationAwareAspectJAutoProxyCreator的继承关系
AnnotationAwareAspectJAutoProxyCreator extends
AnnotationAwareAspectJAutoProxyCreator extends
AspectJAwareAdvisorAutoProxyCreator extends
AbstractAdvisorAutoProxyCreator extends
AbstractAutoProxyCreator
implements SmartInstantiationAwareBeanPostProcessor, BeanFactoryAware
看到这个继承关系，就应该关注整个体系中实现的后置处理器的方法以及BeanFactory的方法，我们发现：
（1） AbstractAutoProxyCreator.setBeanFactory()方法以及
后置处理器的逻辑postProcessBeforeInstantiation方法
（2） AbstractAdvisorAutoProxyCreator这个类有setBeanFactory()方法
首先调用父类的setBeanFactory方法，然后调用initBeanFactory方法
public void setBeanFactory(BeanFactory beanFactory) {
super.setBeanFactory(beanFactory);
if (!(beanFactory instanceof ConfigurableListableBeanFactory)) {
throw new IllegalArgumentException(
"AdvisorAutoProxyCreator requires a ConfigurableListableBeanFactory: " + beanFactory);
}
initBeanFactory((ConfigurableListableBeanFactory) beanFactory);
}（3）AnnotationAwareAspectJAutoProxyCreator里面有initBeanFactory()方法
接下来要做的就是看看这些方法都做了什么
调试源码@EnableAspectJAutoProxy
配置类
@EnableAspectJAutoProxy
@Configuration
public class MainConfigOfAOP {
//业务逻辑类加入容器中
@Bean
public MyCalculator calculator(){
return new MyCalculator();
}
//切面类加入到容器中
@Bean
public LogAspects logAspects(){
return new LogAspects();
}
}业务逻辑类很简单
public class MyCalculator {
public int div(int i,int j){
System.out.println("MathCalculator...div...");
return i/j;
}
}然后是切面类
@Aspect
public class LogAspects {
//抽取公共的切入点表达式
//1、本类引用
//2、其他的切面引用
@Pointcut("execution(public int com.ethan.aop.MyCalculator.*(..))")
public void pointCut(){};
//@Before在目标方法之前切入；切入点表达式（指定在哪个方法切入）
@Before("pointCut()")
public void logStart(JoinPoint joinPoint){
Object[] args = joinPoint.getArgs();
System.out.println(""+joinPoint.getSignature().getName()+"运行。。。@Before:参数列表是：{"+Arrays.asList(args)+"}");
}
@After("com.ethan.aop.LogAspects.pointCut()")
public void logEnd(JoinPoint joinPoint){
System.out.println(""+joinPoint.getSignature().getName()+"结束。。。@After");
}
//JoinPoint一定要出现在参数表的第一位
@AfterReturning(value="pointCut()",returning="result")
public void logReturn(JoinPoint joinPoint,Object result){
System.out.println(""+joinPoint.getSignature().getName()+"正常返回。。。@AfterReturning:运行结果：{"+result+"}");
}
@AfterThrowing(value="pointCut()",throwing="exception")
public void logException(JoinPoint joinPoint,Exception exception){
System.out.println(""+joinPoint.getSignature().getName()+"异常。。。异常信息：{"+exception+"}");
}
@Around(value="pointCut()")
public void logAround(ProceedingJoinPoint joinPoint) throws Throwable {
System.out.println("around before proceed");
joinPoint.proceed();
System.out.println("around after proceed ");
}
}首先进入refresh（）方法
public AnnotationConfigApplicationContext(Class<?>... annotatedClasses) {
this();
register(annotatedClasses);
refresh();
}然后进入方法registerBeanPostProcessors注册bean的后置处理器来方便拦截bean的创建；
// Register bean processors that intercept bean creation.
registerBeanPostProcessors(beanFactory);跟进registerBeanPostProcessors源码
public static void registerBeanPostProcessors(
ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {
//先获取ioc容器已经定义了的需要创建对象的所有BeanPostProcessor
String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);
// Register BeanPostProcessorChecker that logs an info message when
// a bean is created during BeanPostProcessor instantiation, i.e. when
// a bean is not eligible for getting processed by all BeanPostProcessors.
int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));
// Separate between BeanPostProcessors that implement PriorityOrdered,
// Ordered, and the rest.
List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanPostProcessor>();
List<BeanPostProcessor> internalPostProcessors = new ArrayList<BeanPostProcessor>();
List<String> orderedPostProcessorNames = new ArrayList<String>();
List<String> nonOrderedPostProcessorNames = new ArrayList<String>();
//根据后置器的类型方法不同的集合
for (String ppName : postProcessorNames) {
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
priorityOrderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
orderedPostProcessorNames.add(ppName);
}
else {
nonOrderedPostProcessorNames.add(ppName);
}
}
//优先处理实现了PriorityOrdered的处理器
// First, register the BeanPostProcessors that implement PriorityOrdered.
sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);
//接下里处理实现了Ordered的处理器
// Next, register the BeanPostProcessors that implement Ordered.
List<BeanPostProcessor> orderedPostProcessors = new ArrayList<BeanPostProcessor>();
for (String ppName : orderedPostProcessorNames) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
orderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
sortPostProcessors(orderedPostProcessors, beanFactory);
registerBeanPostProcessors(beanFactory, orderedPostProcessors);
//接下来注册没实现优先级接口的BeanPostProcessor；
// Now, register all regular BeanPostProcessors.
List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<BeanPostProcessor>();
for (String ppName : nonOrderedPostProcessorNames) {
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
nonOrderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
//把BeanPostProcessor注册到BeanFactory中
registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);
// Finally, re-register all internal BeanPostProcessors.
sortPostProcessors(internalPostProcessors, beanFactory);
registerBeanPostProcessors(beanFactory, internalPostProcessors);
// Re-register post-processor for detecting inner beans as ApplicationListeners,
// moving it to the end of the processor chain (for picking up proxies etc).
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
} 1 ）先获取ioc容器已经定义了的需要创建对象的所有BeanPostProcessor
2） 给容器中加别的BeanPostProcessor
3 ）优先注册实现了PriorityOrdered接口的BeanPostProcessor；
4） 再给容器中注册实现了Ordered接口的BeanPostProcessor；
因为【AnnotationAwareAspectJAutoProxyCreator】实现了Ordered接口，所以AnnotationAwareAspectJAutoProxyCreator这个BeanPostProcessor在此时注册
List<BeanPostProcessor> orderedPostProcessors = new ArrayList<BeanPostProcessor>();
for (String ppName : orderedPostProcessorNames) {
//创建AnnotationAwareAspectJAutoProxyCreator
BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
orderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
} 下面再复习一下bean的生生命周期：
1）、创建Bean的实例
2）、populateBean；给bean的各种属性赋值
3）、initializeBean：初始化bean；
1）、invokeAwareMethods()：处理Aware接口的方法回调
2）、applyBeanPostProcessorsBeforeInitialization()：应用后置处理器的postProcessBeforeInitialization（）
3）、invokeInitMethods()；执行自定义的初始化方法
4）、applyBeanPostProcessorsAfterInitialization()；执行后置处理器的postProcessAfterInitialization（）；
5 ）接下来注册没实现优先级接口的BeanPostProcessor；
6）、把BeanPostProcessor注册到BeanFactory中； beanFactory.addBeanPostProcessor(postProcessor);
registerBeanPostProcessors(beanFactory, orderedPostProcessors);
/**
* Register the given BeanPostProcessor beans.
*/
private static void registerBeanPostProcessors(
ConfigurableListableBeanFactory beanFactory, List<BeanPostProcessor> postProcessors) {
for (BeanPostProcessor postProcessor : postProcessors) {
beanFactory.addBeanPostProcessor(postProcessor);
}
}至此通过@EnableAspectJAutoProxy这个注解想容器中添加了AnnotationAwareAspectJAutoProxyCreator组件
AnnotationAwareAspectJAutoProxyCreator作为后置处理器的作用
在refresh方法中，已经通过了registerBeanPostProcessors注册了后置处理器，但还是有别的组件类型没有被注册，接下来看这个方法
// Instantiate all remaining (non-lazy-init) singletons.
finishBeanFactoryInitialization(beanFactory);顾名思义，实例化剩下的bean到容器中
在bean的生命周期中，所有的后置处理器都是参与其中的，不难想象，接下来我们要看AnnotationAwareAspectJAutoProxyCreator对剩下的bean的实例化做了什么，跟进源码，在finishBeanFactoryInitialization方法中最后调用了来实例化剩下的bean
// Instantiate all remaining (non-lazy-init) singletons.
beanFactory.preInstantiateSingletons();可以看到该继续跟进到了getBean(beanName);方法，而beanName则是直接从容器中获得的所有定义的beanDefinitionNames遍历所得
List<String> beanNames = new ArrayList<String>(this.beanDefinitionNames);
//代码有省略
for (String beanName : beanNames) {
RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName);
if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {
if (isFactoryBean(beanName)) {
final FactoryBean<?> factory = (FactoryBean<?>) getBean(FACTORY_BEAN_PREFIX + beanName);
boolean isEagerInit;
if (System.getSecurityManager() != null && factory instanceof SmartFactoryBean) {
isEagerInit = AccessController.doPrivileged(new PrivilegedAction<Boolean>() {
@Override
public Boolean run() {
return ((SmartFactoryBean<?>) factory).isEagerInit();
}
}, getAccessControlContext());
}
else {
isEagerInit = (factory instanceof SmartFactoryBean &&
((SmartFactoryBean<?>) factory).isEagerInit());
}
if (isEagerInit) {
getBean(beanName);
}
}
else {
//执行getBean方法来实例化bean
getBean(beanName);
}
}
}同样实例化bean的调用链为getBean->doGetBean()->getSingleton()->getObject（）->createBean()
接下来看createBean的源码
protected Object createBean(String beanName, RootBeanDefinition mbd, Object[] args) throws BeanCreationException {
if (logger.isDebugEnabled()) {
logger.debug("Creating instance of bean '" + beanName + "'");
}
RootBeanDefinition mbdToUse = mbd;
// Make sure bean class is actually resolved at this point, and
// clone the bean definition in case of a dynamically resolved Class
// which cannot be stored in the shared merged bean definition.
Class<?> resolvedClass = resolveBeanClass(mbd, beanName);
if (resolvedClass != null && !mbd.hasBeanClass() && mbd.getBeanClassName() != null) {
mbdToUse = new RootBeanDefinition(mbd);
mbdToUse.setBeanClass(resolvedClass);
}
// Prepare method overrides.
try {
mbdToUse.prepareMethodOverrides();
}
catch (BeanDefinitionValidationException ex) {
throw new BeanDefinitionStoreException(mbdToUse.getResourceDescription(),
beanName, "Validation of method overrides failed", ex);
}
try {
//注意此处，给BeanPostProcessors 一个机会来返回一个代理对象来代替目标实例，如果BeanPostProcessors 返回代理对象则直接方法返回，否则继续执行后面的doCreateBean方法，而doCreateBean才是真正的实例化方法
// Give BeanPostProcessors a chance to return a proxy instead of the target bean instance.
Object bean = resolveBeforeInstantiation(beanName, mbdToUse);
if (bean != null) {
return bean;
}
}
catch (Throwable ex) {
throw new BeanCreationException(mbdToUse.getResourceDescription(), beanName,
"BeanPostProcessor before instantiation of bean failed", ex);
}
Object beanInstance = doCreateBean(beanName, mbdToUse, args);
if (logger.isDebugEnabled()) {
logger.debug("Finished creating instance of bean '" + beanName + "'");
}
return beanInstance;
}注意我注释的resolveBeforeInstantiation方法，给BeanPostProcessors 一个机会来返回一个代理对象来代替目标实例，如果BeanPostProcessors 返回代理对象则直接方法返回，否则继续执行后面的doCreateBean方法，而doCreateBean才是真正的实例化方法。
我们知道，在doCreateBean方法里面会经过实例化，属性赋值等一系列行为，即bean的生命周期，其中applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);和applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);两个方法在初始化方法invokeInitMethods(beanName, wrappedBean, mbd);方法前后执行，源码不再贴出，已经在上一文章讲过，这里要注意的是，此处的后置处理器类型为BeanPostProcessor，而我们之前注册到容器中的后置处理器类型为InstantiationAwareBeanPostProcessor，二者区别是：
【BeanPostProcessor是在Bean对象创建完成初始化前后调用的】
【InstantiationAwareBeanPostProcessor是在创建Bean实例之前先尝试用后置处理器返回对象的】
那么为什么后者是实例化之前处理放回对象呢?看resolveBeforeInstantiation源码：
protected Object resolveBeforeInstantiation(String beanName, RootBeanDefinition mbd) {
Object bean = null;
if (!Boolean.FALSE.equals(mbd.beforeInstantiationResolved)) {
// Make sure bean class is actually resolved at this point.
if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
Class<?> targetType = determineTargetType(beanName, mbd);
if (targetType != null) {
bean = applyBeanPostProcessorsBeforeInstantiation(targetType, beanName);
if (bean != null) {
bean = applyBeanPostProcessorsAfterInitialization(bean, beanName);
}
}
}
mbd.beforeInstantiationResolved = (bean != null);
}
return bean;
}可以看到先调用applyBeanPostProcessorsBeforeInstantiation(targetType, beanName);方法返回bean，如果bean不为null，继续调用applyBeanPostProcessorsAfterInitialization(bean, beanName);方法，看applyBeanPostProcessorsBeforeInstantiation源码：获得所有的后置处理器，如果是InstantiationAwareBeanPostProcessor（BeanPostProcessor的子类）类型，则调用postProcessBeforeInstantiation方法，注意postProcessBeforeInstantiation与BeanPostProcessor类型处理器的postProcessBeforeInitialization名称是不一样的，前者是实例化之前，后者是初始化前后
protected Object applyBeanPostProcessorsBeforeInstantiation(Class<?> beanClass, String beanName) {
for (BeanPostProcessor bp : getBeanPostProcessors()) {
if (bp instanceof InstantiationAwareBeanPostProcessor) {
InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp;
Object result = ibp.postProcessBeforeInstantiation(beanClass, beanName);
if (result != null) {
return result;
}
}
}
return null;
}如此，任何bean的实例化之前都会调用AbstractAutoProxyCreator的postProcessBeforeInstantiation方法来返回一个代理对象
postProcessBeforeInstantiation和postProcessAfterInitialization详解
我们先按顺序看postProcessBeforeInstantiation的源码
public Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException {
Object cacheKey = getCacheKey(beanClass, beanName);
if (beanName == null || !this.targetSourcedBeans.contains(beanName)) {
if (this.advisedBeans.containsKey(cacheKey)) {
return null;
}
if (isInfrastructureClass(beanClass) || shouldSkip(beanClass, beanName)) {
this.advisedBeans.put(cacheKey, Boolean.FALSE);
return null;
}
}
// Create proxy here if we have a custom TargetSource.
// Suppresses unnecessary default instantiation of the target bean:
// The TargetSource will handle target instances in a custom fashion.
if (beanName != null) {
TargetSource targetSource = getCustomTargetSource(beanClass, beanName);
if (targetSource != null) {
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;
}以我们的业务类calculator为例，先从缓存中获得key值即beanName，用于判断是否需要创建代理，，判断条件为如果是基础类或者需要跳过就直接返回null，先看isInfrastructureClass方法：
protected boolean isInfrastructureClass(Class<?> beanClass) {
boolean retVal = Advice.class.isAssignableFrom(beanClass) ||
Pointcut.class.isAssignableFrom(beanClass) ||
Advisor.class.isAssignableFrom(beanClass) ||
AopInfrastructureBean.class.isAssignableFrom(beanClass);
if (retVal && logger.isTraceEnabled()) {
logger.trace("Did not attempt to auto-proxy infrastructure class [" + beanClass.getName() + "]");
}
return retVal;
}表示如果传进来得class是Advice、Pointcut、Advisor、AopInfrastructureBean则返回true，不需创建代理，显然此处返回false，然后看shouldSkip方法：
protected boolean shouldSkip(Class<?> beanClass, String beanName) {
return false;
可以看到方法直接为放回false
接下来如果当前类拥有自定义的TargetSource才会创建代理，所以此处仍没有创建代理
// Create proxy here if we have a custom TargetSource.
// Suppresses unnecessary default instantiation of the target bean:
// The TargetSource will handle target instances in a custom fashion.
if (beanName != null) {
TargetSource targetSource = getCustomTargetSource(beanClass, beanName);
if (targetSource != null) {
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;
}
}
接下来创建bean，然后在bean实例化后并初始化之后，会调用applyBeanPostProcessorsAfterInitialization方法，然后调用AbstractAutoProxyCreator的postProcessAfterInitialization方法
public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
if (bean != null) {
Object cacheKey = getCacheKey(bean.getClass(), beanName);
if (!this.earlyProxyReferences.contains(cacheKey)) {
return wrapIfNecessary(bean, beanName, cacheKey);
}
}
return bean;
}此方法会判断bean有没有被代理过，如果没有，判断是否需要代理
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.
Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);
if (specificInterceptors != DO_NOT_PROXY) {
this.advisedBeans.put(cacheKey, Boolean.TRUE);
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;
}如果有资格被代理，即specificInterceptors 不为空，这里是获得当前bean的可用通知方法，此处我们写了五个，getAdvicesAndAdvisorsForBean方法最终会调用findEligibleAdvisors方法获得所有可以应用到当前bean身上的增强即通知，然后进行排序
protected List<Advisor> findEligibleAdvisors(Class<?> beanClass, String beanName) {
List<Advisor> candidateAdvisors = findCandidateAdvisors();
List<Advisor> eligibleAdvisors = findAdvisorsThatCanApply(candidateAdvisors, beanClass, beanName);
extendAdvisors(eligibleAdvisors);
if (!eligibleAdvisors.isEmpty()) {
//排除
eligibleAdvisors = sortAdvisors(eligibleAdvisors);
}
return eligibleAdvisors;
}获得资格，继续调用createProxy方法创建代理，继而调用proxyFactory.getProxy方法
@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);
}
return new ObjenesisCglibAopProxy(config);
}
else {
return new JdkDynamicAopProxy(config);
}
}可以发现如果当前bean实现了接口，则创建jdk动态代理，否则返回一个cglib动态代理
总结
1、 @EnableAspectJAutoProxy注解给容器中注册一个AnnotationAwareAspectJAutoProxyCreator；
2、 AnnotationAwareAspectJAutoProxyCreator的继承体系中通过后置处理器和initBeanFactory等方法影响后续创建的bean的生命周期，因为配置类的refresh（）方法是先注册后置处理器，再处理剩下的bean
3、 AnnotationAwareAspectJAutoProxyCreator的作用：
1）每一个bean创建之前，调用postProcessBeforeInstantiation()；
2）创建对象
3）初始化对象之后调用postProcessAfterInitialization
最后
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