4.Java Spring框架源码分析-AOP-AnnotationAwareAspectJAutoProxyCreator具体是怎么创建代理对象的
目录
1. 跟踪调用栈至postProcessBeforeInstantiation
我们继续放行断点，观察Calc实例的创建，断点主要停留在3个地方
- org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#postProcessBeforeInstantiation（实例化Calc之前）
- com.zsk.test.aop.AopConfig#calc（创建Calc）
- org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#postProcessAfterInitialization（实例化并且初始化Calc之后）
2. 判断是否需要创建代理对象
- org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#postProcessBeforeInstantiation
public Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException {
Object cacheKey = getCacheKey(beanClass, beanName);
//判断当前bean是否在advisedBeans中（增强了的bean）
if (beanName == null || !this.targetSourcedBeans.contains(beanName)) {
if (this.advisedBeans.containsKey(cacheKey)) {
return null;
}
//判断当前bean是否是Advice、Pointcut、Advisor、AopInfrastructureBean其中的一种或者是否是切面（@Aspect修饰的）
//或者是否需要跳过：org.springframework.aop.aspectj.autoproxy.AspectJAwareAdvisorAutoProxyCreator#shouldSkip
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;
}
2.1. 不需要创建代理对象的情况
- org.springframework.aop.aspectj.autoproxy.AspectJAwareAdvisorAutoProxyCreator#shouldSkip
protected boolean shouldSkip(Class<?> beanClass, String beanName) {
// 获取所有的增强器（切面里面的通知方法）
List<Advisor> candidateAdvisors = findCandidateAdvisors();
//判断是否是AspectJPointcutAdvisor类型的
for (Advisor advisor : candidateAdvisors) {
if (advisor instanceof AspectJPointcutAdvisor) {
if (((AbstractAspectJAdvice) advisor.getAdvice()).getAspectName().equals(beanName)) {
return true;
}
}
}
return super.shouldSkip(beanClass, beanName);
}
3. 其他情况为bean创建代理对象
- AbstractAutoProxyCreator#postProcessAfterInitialization
public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
if (bean != null) {
Object cacheKey = getCacheKey(bean.getClass(), beanName);
if (this.earlyProxyReferences.remove(cacheKey) != bean) {
//如果有代理类的话使用代理类包装
return wrapIfNecessary(bean, beanName, cacheKey);
}
}
return bean;
}
3.1. 用增强器包装
- AbstractAutoProxyCreator#wrapIfNecessary
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;
}
// 如果有增强器的话创建代理类
//获取所有能应用到当前bean的代理类
Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);
if (specificInterceptors != DO_NOT_PROXY) {
this.advisedBeans.put(cacheKey, Boolean.TRUE);
//创建代理类
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;
}
3.1.1. 找出合适的增强器
- AbstractAdvisorAutoProxyCreator#findEligibleAdvisors
protected List<Advisor> findEligibleAdvisors(Class<?> beanClass, String beanName) {
//获取所有的增强器
List<Advisor> candidateAdvisors = findCandidateAdvisors();
//筛选出能引用的增强器
List<Advisor> eligibleAdvisors = findAdvisorsThatCanApply(candidateAdvisors, beanClass, beanName);
extendAdvisors(eligibleAdvisors);
if (!eligibleAdvisors.isEmpty()) {
//排个序
eligibleAdvisors = sortAdvisors(eligibleAdvisors);
}
return eligibleAdvisors;
}
3.1.2. 用增强器去创建代理对象
- AbstractAutoProxyCreator#createProxy
protected Object createProxy(
Class<?> beanClass, String beanName, Object[] specificInterceptors, TargetSource targetSource) {
if (this.beanFactory instanceof ConfigurableListableBeanFactory) {
AutoProxyUtils.exposeTargetClass((ConfigurableListableBeanFactory) this.beanFactory, beanName, beanClass);
}
ProxyFactory proxyFactory = new ProxyFactory();
proxyFactory.copyFrom(this);
if (!proxyFactory.isProxyTargetClass()) {
if (shouldProxyTargetClass(beanClass, beanName)) {
proxyFactory.setProxyTargetClass(true);
}
else {
evaluateProxyInterfaces(beanClass, proxyFactory);
}
}
//把所有增强器放到ProxyFactory中
Advisor[] advisors = buildAdvisors(beanName, specificInterceptors);
proxyFactory.addAdvisors(advisors);
proxyFactory.setTargetSource(targetSource);
customizeProxyFactory(proxyFactory);
proxyFactory.setFrozen(this.freezeProxy);
if (advisorsPreFiltered()) {
proxyFactory.setPreFiltered(true);
}
//使用proxyfactory创建代理类
return proxyFactory.getProxy(getProxyClassLoader());
}
- ProxyFactory#getProxy(java.lang.ClassLoader)
public Object getProxy(ClassLoader classLoader) {
return createAopProxy().getProxy(classLoader);
}
3.1.2.1. 根据情况使用JDK或者CGLIB创建代理对象
- DefaultAopProxyFactory#createAopProxy
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);
}
//cglib的代理
return new ObjenesisCglibAopProxy(config);
}
else {
//jdk动态代理
return new JdkDynamicAopProxy(config);
}
}
4. 以后从容器中获取的Calc就是代理类
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