@[TOC]
系列文档索引
SpringAOP从入门到源码分析大全（一）熟悉动态代理 SpringAOP从入门到源码分析大全（二）熟悉ProxyFactory SpringAOP从入门到源码分析大全（三）ProxyFactory源码分析 SpringAOP从入门到源码分析大全（四）SpringAOP的源码分析 SpringAOP从入门到源码分析大全（五）手写一个编程式AOP
五、ProxyFactory源码分析
1、案例
UserService userService = new UserService();
// spring 将cglib和jdk动态代理合二为一了，如果有接口，就会走jdk代理，如果只有类，就会走cglib代理
ProxyFactory proxyFactory = new ProxyFactory();
proxyFactory.setTarget(userService);
// 可以设置多个Advice，会形成代理链
proxyFactory.addAdvice(new MyBeforeAdvice());
proxyFactory.addAdvice(new MyAroundAdvice());
proxyFactory.addAdvice(new MyAfterAdvice());
proxyFactory.addAdvisor(new PointcutAdvisor() {
@Override
public Pointcut getPointcut() {
return new Pointcut() {
@Override
public ClassFilter getClassFilter() {
return new ClassFilter() {
@Override
public boolean matches(Class<?> clazz) {
// 类匹配器
return false;
}
};
}
@Override
public MethodMatcher getMethodMatcher() {
// 方法匹配器
return new MethodMatcher() {
@Override
public boolean matches(Method method, Class<?> targetClass) {
return false;
}
@Override
public boolean isRuntime() {
return false; // 如果为true时，下面的参数matches就会生效
}
@Override
public boolean matches(Method method, Class<?> targetClass, Object... args) {
return false;
}
};
}
};
}
@Override
public Advice getAdvice() {
return new MyAfterAdvice();
}
// 没用
@Override
public boolean isPerInstance() {
return true;
}
});
UserService proxy = (UserService) proxyFactory.getProxy();
proxy.test();
2、认识TargetSource
（1）何时用到TargetSource
我们在调用proxyFactory.setTarget方法时，是将原始对象封装为了SingletonTargetSource。
SingletonTargetSource实现了TargetSource接口，相当于非常简单的一个TargetSource。
// 动态目标源可以支持池化、热插拔等。
public interface TargetSource extends TargetClassAware {
// 返回TargetSource返回的目标类型。
@Override
@Nullable
Class<?> getTargetClass();
// true表示目标不可变，意味着会缓存Target
boolean isStatic();
// 返回目标实例。在AOP框架调用AOP方法调用的“目标”之前立即调用。
@Nullable
Object getTarget() throws Exception;
// 释放从getTarget()方法获得的给定目标对象(如果有的话)。
void releaseTarget(Object target) throws Exception;
}
其实，AOP代理的对象，每次调用代理对象的方法时，获取的原始对象就是从TargetSource 的getTarget方法中获取的，这就意味着具备了很强的灵活性。
（2）@Lazy的原理
@Autowired
private UserService userService;
在属性注入时，使用@Lazy注解，并不会初始化Bean，而是将代理对象赋值给了属性。
我们看一下@Lazy属性赋值的源码：
// org.springframework.context.annotation.ContextAnnotationAutowireCandidateResolver#buildLazyResolutionProxy
protected Object buildLazyResolutionProxy(final DependencyDescriptor descriptor, final @Nullable String beanName) {
BeanFactory beanFactory = getBeanFactory();
Assert.state(beanFactory instanceof DefaultListableBeanFactory,
"BeanFactory needs to be a DefaultListableBeanFactory");
final DefaultListableBeanFactory dlbf = (DefaultListableBeanFactory) beanFactory;
TargetSource ts = new TargetSource() {
@Override
public Class<?> getTargetClass() {
return descriptor.getDependencyType();
}
@Override
public boolean isStatic() {
return false;
}
@Override
public Object getTarget() {
Set<String> autowiredBeanNames = (beanName != null ? new LinkedHashSet<>(1) : null);
Object target = dlbf.doResolveDependency(descriptor, beanName, autowiredBeanNames, null);
if (target == null) {
Class<?> type = getTargetClass();
if (Map.class == type) {
return Collections.emptyMap();
}
else if (List.class == type) {
return Collections.emptyList();
}
else if (Set.class == type || Collection.class == type) {
return Collections.emptySet();
}
throw new NoSuchBeanDefinitionException(descriptor.getResolvableType(),
"Optional dependency not present for lazy injection point");
}
if (autowiredBeanNames != null) {
for (String autowiredBeanName : autowiredBeanNames) {
if (dlbf.containsBean(autowiredBeanName)) {
dlbf.registerDependentBean(autowiredBeanName, beanName);
}
}
}
return target;
}
@Override
public void releaseTarget(Object target) {
}
};
ProxyFactory pf = new ProxyFactory();
pf.setTargetSource(ts);
Class<?> dependencyType = descriptor.getDependencyType();
if (dependencyType.isInterface()) {
pf.addInterface(dependencyType);
}
return pf.getProxy(dlbf.getBeanClassLoader());
}
上面的源码可以看出，就是将属性赋值了一个代理对象，而TargetSource 的getTarget方法，就是从容器中获取目标对象的Bean进行返回。很巧妙的实现了懒加载。
（3）应用TargetSource
实际上我们日常开发中，很少会用到TargetSource。
我们也可以使用TargetSource实现懒加载、池化（每次获取Target都是从池子里获取）、热插拔（每次获取Target都是重新获取）。
3、ProxyFactory选择cglib或jdk动态代理原理
ProxyFactory在生成代理对象之前需要决定到底是使用JDK动态代理还是CGLIB技术：
// org.springframework.aop.framework.DefaultAopProxyFactory#createAopProxy
@Override
public AopProxy createAopProxy(AdvisedSupport config) throws AopConfigException {
// 是GraalVM 就直接用jdk代理
// Optimize == true或者isProxyTargetClass == true 或者配置了接口，就走jdk
if (!NativeDetector.inNativeImage() &&
(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.");
}
// 被代理的类是接口 或 被代理的类已经是jdk代理类了 或 lambda表达式 就用jdk
if (targetClass.isInterface() || Proxy.isProxyClass(targetClass) || ClassUtils.isLambdaClass(targetClass)) {
return new JdkDynamicAopProxy(config);
}
return new ObjenesisCglibAopProxy(config);
}
else {
return new JdkDynamicAopProxy(config);
}
}
然后获取代理类的方法，就是jdk和cglib代理的逻辑。
4、jdk代理获取代理方法的逻辑
JdkDynamicAopProxy实现了InvocationHandler方法，JdkDynamicAopProxy调用其getProxy方法，执行目标方法就会执行JdkDynamicAopProxy的invoke方法：
@Override
@Nullable
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
Object oldProxy = null;
boolean setProxyContext = false;
// 拿到被代理对象
TargetSource targetSource = this.advised.targetSource;
Object target = null;
try {
// 如果接口中没有定义equals()方法，那么直接调用，不走代理
if (!this.equalsDefined && AopUtils.isEqualsMethod(method)) {
// The target does not implement the equals(Object) method itself.
return equals(args[0]);
}
else if (!this.hashCodeDefined && AopUtils.isHashCodeMethod(method)) {
// The target does not implement the hashCode() method itself.
return hashCode();
}
else if (method.getDeclaringClass() == DecoratingProxy.class) {
// There is only getDecoratedClass() declared -> dispatch to proxy config.
// 得到代理对象的类型，而不是所实现的接口
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...
// 也是直接调用Advised接口中的方法，不走代理逻辑
// 其实就是利用代理对象获取ProxyFactory中的信息
return AopUtils.invokeJoinpointUsingReflection(this.advised, method, args);
}
Object retVal;
// 如果ProxyFactory的exposeProxy为true，则将代理对象设置到currentProxy这个ThreadLocal中去
// 如果使用@EnableAspectJAutoProxy注解，需要手动将该参数设置为true，默认为false
if (this.advised.exposeProxy) {
// Make invocation available if necessary.
oldProxy = AopContext.setCurrentProxy(proxy);
setProxyContext = true;
}
// Get as late as possible to minimize the time we "own" the target,
// in case it comes from a pool.
// 被代理对象和代理类
target = targetSource.getTarget();
Class<?> targetClass = (target != null ? target.getClass() : null);
// Get the interception chain for this method.
// 代理对象在执行某个方法时，根据方法筛选出匹配的Advisor，并适配成Interceptor 代理链
List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);
// Check whether we have any advice. If we don't, we can fall back on direct
// reflective invocation of the target, and avoid creating a MethodInvocation.
if (chain.isEmpty()) {
// We can skip creating a MethodInvocation: just invoke the target directly
// Note that the final invoker must be an InvokerInterceptor so we know it does
// nothing but a reflective operation on the target, and no hot swapping or fancy proxying.
// 如果没有Advice，则直接调用对应方法
Object[] argsToUse = AopProxyUtils.adaptArgumentsIfNecessary(method, args);
retVal = AopUtils.invokeJoinpointUsingReflection(target, method, argsToUse);
}
else {
// We need to create a method invocation...
MethodInvocation invocation =
new ReflectiveMethodInvocation(proxy, target, method, args, targetClass, chain);
// Proceed to the joinpoint through the interceptor chain.
retVal = invocation.proceed(); // 执行下一步
}
// 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);
}
}
}
（1）getInterceptorsAndDynamicInterceptionAdvice获取拦截器链
// org.springframework.aop.framework.AdvisedSupport#getInterceptorsAndDynamicInterceptionAdvice
public List<Object> getInterceptorsAndDynamicInterceptionAdvice(Method method, @Nullable Class<?> targetClass) {
// 代理对象在执行某个方法时，会根据当前ProxyFactory中所设置的Advisor根据当前method再次进行过滤
MethodCacheKey cacheKey = new MethodCacheKey(method);
// 注意这个List，表示的就是Advice，有缓存。
List<Object> cached = this.methodCache.get(cacheKey);
if (cached == null) {
cached = this.advisorChainFactory.getInterceptorsAndDynamicInterceptionAdvice(
this, method, targetClass);
this.methodCache.put(cacheKey, cached);
}
return cached;
}
// org.springframework.aop.framework.DefaultAdvisorChainFactory#getInterceptorsAndDynamicInterceptionAdvice
@Override
public List<Object> getInterceptorsAndDynamicInterceptionAdvice(
Advised config, Method method, @Nullable Class<?> targetClass) {
// This is somewhat tricky... We have to process introductions first,
// but we need to preserve order in the ultimate list.
AdvisorAdapterRegistry registry = GlobalAdvisorAdapterRegistry.getInstance();
// 从ProxyFactory中拿到所设置的Advice，（添加时被封装成了DefaultPointcutAdvisor）
// 添加的时候会控制顺序
Advisor[] advisors = config.getAdvisors();
List<Object> interceptorList = new ArrayList<>(advisors.length);
Class<?> actualClass = (targetClass != null ? targetClass : method.getDeclaringClass());
Boolean hasIntroductions = null;
for (Advisor advisor : advisors) {
if (advisor instanceof PointcutAdvisor) {
// Add it conditionally.
PointcutAdvisor pointcutAdvisor = (PointcutAdvisor) advisor;
// 先匹配类
if (config.isPreFiltered() || pointcutAdvisor.getPointcut().getClassFilter().matches(actualClass)) {
MethodMatcher mm = pointcutAdvisor.getPointcut().getMethodMatcher();
boolean match;
// 再匹配方法
if (mm instanceof IntroductionAwareMethodMatcher) {
if (hasIntroductions == null) {
hasIntroductions = hasMatchingIntroductions(advisors, actualClass);
}
match = ((IntroductionAwareMethodMatcher) mm).matches(method, actualClass, hasIntroductions);
}
else {
match = mm.matches(method, actualClass);
}
if (match) {
// 如果匹配，则将Advisor封装成Interceptor，当前Advisor中的Advice可能既是MethodBeforeAdvice也是ThrowingAdvice，除了around的都需要包装
MethodInterceptor[] interceptors = registry.getInterceptors(advisor);
if (mm.isRuntime()) { // true 需要包装Interceptor，会将参数传过来进行判断
// 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));
}
}
// 最终，interceptorList中存储的是当前正在执行的Method所匹配的MethodInterceptor，可能是动态的，也可能是非动态的。
// 找到Method所匹配的MethodInterceptor后，就会开始调用这些MethodInterceptor，如果是动态的，会额外进行方法参数的匹配判断
}
}
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;
}
（2）包装AfterReturningAdvice、MethodBeforeAdvice为MethodInterceptor
包装的MethodInterceptor和around的效果是一样的。
ThrowsAdviceInterceptor：复杂一些，会将异常类型匹配出来
（3）总结
在构造JdkDynamicAopProxy对象时，会先拿到被代理对象自己所实现的接口，并且额外的增加SpringProxy、Advised、DecoratingProxy三个接口，组合成一个Class[]，并赋值给proxiedInterfaces属性
并且检查这些接口中是否定义了equals()、hashcode()方法
执行Proxy.newProxyInstance(classLoader, this.proxiedInterfaces, this)，得到代理对象，JdkDynamicAopProxy作为InvocationHandler，代理对象在执行某个方法时，会进入到JdkDynamicAopProxy的**invoke()**方法中
5、cglib代理获取代理方法的逻辑
CglibAopProxy的getProxy方法逻辑：
// org.springframework.aop.framework.CglibAopProxy#getProxy(java.lang.ClassLoader)
@Override
public Object getProxy(@Nullable ClassLoader classLoader) {
if (logger.isTraceEnabled()) {
logger.trace("Creating CGLIB proxy: " + this.advised.getTargetSource());
}
try {
// 被代理的类
Class<?> rootClass = this.advised.getTargetClass();
Assert.state(rootClass != null, "Target class must be available for creating a CGLIB proxy");
Class<?> proxySuperClass = rootClass;
// 如果被代理类本身就已经是cglib所生成的类了
if (rootClass.getName().contains(ClassUtils.CGLIB_CLASS_SEPARATOR)) {
// 获取真正的被代理类
proxySuperClass = rootClass.getSuperclass();
// 获取被代理类所实现的接口
Class<?>[] additionalInterfaces = rootClass.getInterfaces();
for (Class<?> additionalInterface : additionalInterfaces) {
this.advised.addInterface(additionalInterface);
}
}
// Validate the class, writing log messages as necessary.
validateClassIfNecessary(proxySuperClass, classLoader);
// Configure CGLIB Enhancer...
Enhancer enhancer = createEnhancer();
if (classLoader != null) {
enhancer.setClassLoader(classLoader);
if (classLoader instanceof SmartClassLoader &&
((SmartClassLoader) classLoader).isClassReloadable(proxySuperClass)) {
enhancer.setUseCache(false);
}
}
// 被代理类，代理类的父类
enhancer.setSuperclass(proxySuperClass);
// 代理类额外要实现的接口
enhancer.setInterfaces(AopProxyUtils.completeProxiedInterfaces(this.advised));
enhancer.setNamingPolicy(SpringNamingPolicy.INSTANCE);
enhancer.setStrategy(new ClassLoaderAwareGeneratorStrategy(classLoader));
// 获取和被代理类所匹配的Advisor
Callback[] callbacks = getCallbacks(rootClass);
Class<?>[] types = new Class<?>[callbacks.length];
for (int x = 0; x < types.length; x++) {
types[x] = callbacks[x].getClass();
}
// fixedInterceptorMap only populated at this point, after getCallbacks call above
enhancer.setCallbackFilter(new ProxyCallbackFilter(
this.advised.getConfigurationOnlyCopy(), this.fixedInterceptorMap, this.fixedInterceptorOffset));
enhancer.setCallbackTypes(types);
// Generate the proxy class and create a proxy instance.
return createProxyClassAndInstance(enhancer, callbacks);
}
catch (CodeGenerationException | IllegalArgumentException ex) {
throw new AopConfigException("Could not generate CGLIB subclass of " + this.advised.getTargetClass() +
": Common causes of this problem include using a final class or a non-visible class",
ex);
}
catch (Throwable ex) {
// TargetSource.getTarget() failed
throw new AopConfigException("Unexpected AOP exception", ex);
}
}
（1）getCallbacks获取callback方法
// org.springframework.aop.framework.CglibAopProxy#getCallbacks
private Callback[] getCallbacks(Class<?> rootClass) throws Exception {
// Parameters used for optimization choices...
boolean isFrozen = this.advised.isFrozen();
boolean exposeProxy = this.advised.isExposeProxy();
boolean isStatic = this.advised.getTargetSource().isStatic();
// Choose an "aop" interceptor (used for AOP calls).
// 重要
Callback aopInterceptor = new DynamicAdvisedInterceptor(this.advised);
// Choose a "straight to target" interceptor. (used for calls that are
// unadvised but can return this). May be required to expose the proxy.
Callback targetInterceptor;
if (exposeProxy) {
targetInterceptor = (isStatic ?
new StaticUnadvisedExposedInterceptor(this.advised.getTargetSource().getTarget()) :
new DynamicUnadvisedExposedInterceptor(this.advised.getTargetSource()));
}
else {
targetInterceptor = (isStatic ?
new StaticUnadvisedInterceptor(this.advised.getTargetSource().getTarget()) :
new DynamicUnadvisedInterceptor(this.advised.getTargetSource()));
}
// Choose a "direct to target" dispatcher (used for
// unadvised calls to static targets that cannot return this).
Callback targetDispatcher = (isStatic ?
new StaticDispatcher(this.advised.getTargetSource().getTarget()) : new SerializableNoOp());
Callback[] mainCallbacks = new Callback[] {
aopInterceptor, // for normal advice
targetInterceptor, // invoke target without considering advice, if optimized
new SerializableNoOp(), // no override for methods mapped to this
targetDispatcher, this.advisedDispatcher,
new EqualsInterceptor(this.advised),
new HashCodeInterceptor(this.advised)
};
Callback[] callbacks;
// If the target is a static one and the advice chain is frozen,
// then we can make some optimizations by sending the AOP calls
// direct to the target using the fixed chain for that method.
if (isStatic && isFrozen) {
Method[] methods = rootClass.getMethods();
Callback[] fixedCallbacks = new Callback[methods.length];
this.fixedInterceptorMap = CollectionUtils.newHashMap(methods.length);
// TODO: small memory optimization here (can skip creation for methods with no advice)
for (int x = 0; x < methods.length; x++) {
Method method = methods[x];
List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, rootClass);
fixedCallbacks[x] = new FixedChainStaticTargetInterceptor(
chain, this.advised.getTargetSource().getTarget(), this.advised.getTargetClass());
this.fixedInterceptorMap.put(method, x);
}
// Now copy both the callbacks from mainCallbacks
// and fixedCallbacks into the callbacks array.
callbacks = new Callback[mainCallbacks.length + fixedCallbacks.length];
System.arraycopy(mainCallbacks, 0, callbacks, 0, mainCallbacks.length);
System.arraycopy(fixedCallbacks, 0, callbacks, mainCallbacks.length, fixedCallbacks.length);
this.fixedInterceptorOffset = mainCallbacks.length;
}
else {
callbacks = mainCallbacks;
}
return callbacks;
}
// org.springframework.aop.framework.CglibAopProxy.DynamicAdvisedInterceptor#intercept
@Override
@Nullable
public Object intercept(Object proxy, Method method, Object[] args, MethodProxy methodProxy) throws Throwable {
Object oldProxy = null;
boolean setProxyContext = false;
Object target = null;
TargetSource targetSource = this.advised.getTargetSource();
try {
if (this.advised.exposeProxy) {
// Make invocation available if necessary.
oldProxy = AopContext.setCurrentProxy(proxy);
setProxyContext = true;
}
// Get as late as possible to minimize the time we "own" the target, in case it comes from a pool...
target = targetSource.getTarget();
Class<?> targetClass = (target != null ? target.getClass() : null);
List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);
Object retVal;
// Check whether we only have one InvokerInterceptor: that is,
// no real advice, but just reflective invocation of the target.
if (chain.isEmpty() && CglibMethodInvocation.isMethodProxyCompatible(method)) {
// We can skip creating a MethodInvocation: just invoke the target directly.
// Note that the final invoker must be an InvokerInterceptor, so we know
// it does nothing but a reflective operation on the target, and no hot
// swapping or fancy proxying.
Object[] argsToUse = AopProxyUtils.adaptArgumentsIfNecessary(method, args);
retVal = invokeMethod(target, method, argsToUse, methodProxy);
}
else {
// We need to create a method invocation...
retVal = new CglibMethodInvocation(proxy, target, method, args, targetClass, chain, methodProxy).proceed();
}
retVal = processReturnType(proxy, target, method, retVal);
return retVal;
}
finally {
if (target != null && !targetSource.isStatic()) {
targetSource.releaseTarget(target);
}
if (setProxyContext) {
// Restore old proxy.
AopContext.setCurrentProxy(oldProxy);
}
}
}
（2）总结
创建Enhancer对象
设置Enhancer的superClass为通过ProxyFactory.setTarget()所设置的对象的类
设置Enhancer的interfaces为通过ProxyFactory.addInterface()所添加的接口，以及SpringProxy、Advised、DecoratingProxy接口
设置Enhancer的Callbacks为DynamicAdvisedInterceptor
最后创建一个代理对象，代理对象在执行某个方法时，会进入到DynamicAdvisedInterceptor的intercept()方法中
6、执行器链执行逻辑
// org.springframework.aop.framework.ReflectiveMethodInvocation#proceed
@Override
@Nullable
public Object proceed() throws Throwable {
// We start with an index of -1 and increment early.
// 当调用完了最后一个interceptor后会就执行被代理方法
if (this.currentInterceptorIndex == this.interceptorsAndDynamicMethodMatchers.size() - 1) {
// 调用目标方法
return invokeJoinpoint();
}
// currentInterceptorIndex 初始值 - 1
Object interceptorOrInterceptionAdvice =
this.interceptorsAndDynamicMethodMatchers.get(++this.currentInterceptorIndex);
// 当前interceptor是InterceptorAndDynamicMethodMatcher，则先进行匹配，匹配成功后再调用该Interceptor
// 如果没有匹配则递归调用proceed()方法，调用下一个interceptor
if (interceptorOrInterceptionAdvice instanceof InterceptorAndDynamicMethodMatcher) {
// Evaluate dynamic method matcher here: static part will already have
// been evaluated and found to match.
InterceptorAndDynamicMethodMatcher dm =
(InterceptorAndDynamicMethodMatcher) interceptorOrInterceptionAdvice;
Class<?> targetClass = (this.targetClass != null ? this.targetClass : this.method.getDeclaringClass());
// 动态匹配，根据方法参数匹配
if (dm.methodMatcher.matches(this.method, targetClass, this.arguments)) {
return dm.interceptor.invoke(this);
}
else {
// Dynamic matching failed.
// Skip this interceptor and invoke the next in the chain.
// 不匹配则执行下一个MethodInterceptor
return proceed();
}
}
else {
// It's an interceptor, so we just invoke it: The pointcut will have
// been evaluated statically before this object was constructed.
// 直接调用MethodInterceptor，传入this，在内部会再次调用proceed方法进行递归
// 比如MethodBeforeAdviceInterceptor
return ((MethodInterceptor) interceptorOrInterceptionAdvice).invoke(this);
}
}
在使用ProxyFactory创建代理对象之前，需要往ProxyFactory先添加Advisor
代理对象在执行某个方法时，会把ProxyFactory中的Advisor拿出来和当前正在执行的方法进行匹配筛选
把和方法所匹配的Advisor适配成MethodInterceptor
把和当前方法匹配的MethodInterceptor链，以及被代理对象、代理对象、代理类、当前Method对象、方法参数封装为MethodInvocation对象
调用MethodInvocation的proceed()方法，开始执行各个MethodInterceptor以及被代理对象的对应方法
按顺序调用每个MethodInterceptor的invoke()方法，并且会把MethodInvocation对象传入invoke()方法
直到执行完最后一个MethodInterceptor了，就会调用invokeJoinpoint()方法，从而执行被代理对象的当前方法
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