spring aop底层源码执行逻辑剖析(源码解析)

尤芙蓉 · 发表于 2024-9-22 07:10:41

aop动态代理源码剖析

aop增强逻辑的执行时机是在initializeBean方法中

protected Object initializeBean(String beanName, Object bean, @Nullable RootBeanDefinition mbd) {
if (beanName.indexOf("my") >= 0) {
System.out.println("============= [initializeBean] beanName=" + beanName + " =============");
}
if (System.getSecurityManager() != null) {
AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
invokeAwareMethods(beanName, bean);
return null;
}, getAccessControlContext());
}
else {
invokeAwareMethods(beanName, bean);
}
Object wrappedBean = bean;
if (mbd == null || !mbd.isSynthetic()) {
wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
}
try {
invokeInitMethods(beanName, wrappedBean, mbd);
}
catch (Throwable ex) {
throw new BeanCreationException(
(mbd != null ? mbd.getResourceDescription() : null),
beanName, "Invocation of init method failed", ex);
}
if (mbd == null || !mbd.isSynthetic()) {
// aop增强逻辑的执行时机
// 说白了就是在BeanPostProcessor#postProcessAfterInitialization
wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
}
return wrappedBean;
}

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org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator#postProcessAfterInitialization

@Override
public Object postProcessAfterInitialization(@Nullable Object bean, String beanName) {
if (bean != null) {
Object cacheKey = getCacheKey(bean.getClass(), beanName);
if (this.earlyProxyReferences.remove(cacheKey) != bean) {
// 如果它有资格被代理
return wrapIfNecessary(bean, beanName, cacheKey);
}
}
return bean;
}

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protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) {
// 以下三种情况，判断，如果不需要增强，就直接返回
if (StringUtils.hasLength(beanName) && this.targetSourcedBeans.contains(beanName)) {
return bean;
}
if (Boolean.FALSE.equals(this.advisedBeans.get(cacheKey))) {
return bean;
}
// 如果是基础设施类（Pointcut、Advice、Advisor 等）或需要 skip，则不需要增强
if (isInfrastructureClass(bean.getClass()) || shouldSkip(bean.getClass(), beanName)) {
this.advisedBeans.put(cacheKey, Boolean.FALSE);
return bean;
}
// Create proxy if we have advice.
// 为目标 bean 查找合适的通知器，并封装成一个排好顺序的List<Advisor>集合
// 底层是基于拓扑排序
Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);
if (specificInterceptors != DO_NOT_PROXY) {
this.advisedBeans.put(cacheKey, Boolean.TRUE);
// 创建代理
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;
}

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protected boolean isInfrastructureClass(Class<?> beanClass) {
// 下面这些是基础设施类，说白了就是aop的一些配置类，是不需要被增强的
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;
}

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创建动态代理底层逻辑createProxy()

protected Object createProxy(Class<?> beanClass, @Nullable String beanName,
@Nullable Object[] specificInterceptors, TargetSource targetSource) {
if (this.beanFactory instanceof ConfigurableListableBeanFactory) {
AutoProxyUtils.exposeTargetClass((ConfigurableListableBeanFactory) this.beanFactory, beanName, beanClass);
}
// 通过代理工厂创建代理
ProxyFactory proxyFactory = new ProxyFactory();
proxyFactory.copyFrom(this);
// 设置代理模式
// 在EnableAspectJAutoProxy注解中，有一个属性proxyTargetClass
// boolean proxyTargetClass() default false;
// 表示默认使用的是jdk动态代理，如果设置为true则会使用cglib动态代理
if (proxyFactory.isProxyTargetClass()) {
// Explicit handling of JDK proxy targets and lambdas (for introduction advice scenarios)
if (Proxy.isProxyClass(beanClass) || ClassUtils.isLambdaClass(beanClass)) {
// Must allow for introductions; can't just set interfaces to the proxy's interfaces only.
for (Class<?> ifc : beanClass.getInterfaces()) {
proxyFactory.addInterface(ifc);
}
}
}
else {
// No proxyTargetClass flag enforced, let's apply our default checks...
// 如果没有接口，则会赋值为true，强制使用cglib动态代理
if (shouldProxyTargetClass(beanClass, beanName)) {
proxyFactory.setProxyTargetClass(true);
}
else {
evaluateProxyInterfaces(beanClass, proxyFactory);
}
}
Advisor[] advisors = buildAdvisors(beanName, specificInterceptors);
proxyFactory.addAdvisors(advisors);
proxyFactory.setTargetSource(targetSource);
customizeProxyFactory(proxyFactory);
proxyFactory.setFrozen(this.freezeProxy);
if (advisorsPreFiltered()) {
proxyFactory.setPreFiltered(true);
}
// Use original ClassLoader if bean class not locally loaded in overriding class loader
ClassLoader classLoader = getProxyClassLoader();
if (classLoader instanceof SmartClassLoader && classLoader != beanClass.getClassLoader()) {
classLoader = ((SmartClassLoader) classLoader).getOriginalClassLoader();
}
// 使用工厂模式真正创建动态代理
return proxyFactory.getProxy(classLoader);
}

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proxyFactory.getProxy(classLoader);底层逻辑

public Object getProxy(@Nullable ClassLoader classLoader) {
// 创建 AopProxy 对象
// 调用 AopProxy.getProxy 创建代理对象
return createAopProxy().getProxy(classLoader);
}

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@Override
public AopProxy createAopProxy(AdvisedSupport config) throws AopConfigException {
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.");
}
if (targetClass.isInterface() || Proxy.isProxyClass(targetClass) || ClassUtils.isLambdaClass(targetClass)) {
return new JdkDynamicAopProxy(config);// 使用jdk创建动态代理
}
return new ObjenesisCglibAopProxy(config); // 使用cglib创建动态代理
}
else {
return new JdkDynamicAopProxy(config);// 使用jdk创建动态代理
}
}

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使用jdk的方式创建动态代理

org.springframework.aop.framework.JdkDynamicAopProxy#getProxy(java.lang.ClassLoader)

@Override
public Object getProxy(@Nullable ClassLoader classLoader) {
if (logger.isTraceEnabled()) {
logger.trace("Creating JDK dynamic proxy: " + this.advised.getTargetSource());
}
return Proxy.newProxyInstance(classLoader, this.proxiedInterfaces, this);
}

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因为jdk动态代理的最重要的方法是java.lang.reflect.InvocationHandler#invoke

重点看该类中的invoke方法

@Override
@Nullable
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
Object oldProxy = null;
boolean setProxyContext = false;
TargetSource targetSource = this.advised.targetSource;
Object target = null;
try {
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.
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...
return AopUtils.invokeJoinpointUsingReflection(this.advised, method, args);
}
Object retVal;
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);
// Get the interception chain for this method.
// 获取到所有的通知拦截器
// 0 = {ExposeInvocationInterceptor}
// 1 = {AspectJAroundAdvice}
// 2 = {MethodBeforeAdviceInterceptor}
// 3 = {AspectJAfterAdvice}
// 4 = {AfterReturningAdviceInterceptor}
// 5 = {AspectJAfterThrowingAdvice}
List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);
// Check whether we have any advice. If we don't, we can fallback 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.
// 如果没有拦截器，则直接调用目标方法
Object[] argsToUse = AopProxyUtils.adaptArgumentsIfNecessary(method, args);
retVal = AopUtils.invokeJoinpointUsingReflection(target, method, argsToUse);
}
else {
// We need to create a method invocation...
// 创建一个方法调用器，将拦截器链传入
MethodInvocation invocation =
new ReflectiveMethodInvocation(proxy, target, method, args, targetClass, chain);
// Proceed to the joinpoint through the interceptor chain.
// 通过拦截器链进入连接点。
retVal = invocation.proceed();
}
// 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);
}
}
}

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org.springframework.aop.framework.ReflectiveMethodInvocation#proceed

/**
* Index from 0 of the current interceptor we're invoking.
* -1 until we invoke: then the current interceptor.
*/
// 我们正在调用的拦截器的索引
private int currentInterceptorIndex = -1;
@Override
@Nullable
public Object proceed() throws Throwable {
// We start with an index of -1 and increment early.
// 也就是说当所有拦截器都执行完成后，执行目标方法
if (this.currentInterceptorIndex == this.interceptorsAndDynamicMethodMatchers.size() - 1) {
return invokeJoinpoint(); // 目标方法的执行
}
// interceptorsAndDynamicMethodMatchers表示我们通过构造方法传过来的拦截器
// interceptorOrInterceptionAdvice：渠道的拦截器（或者叫做切面逻辑）
Object interceptorOrInterceptionAdvice =
this.interceptorsAndDynamicMethodMatchers.get(++this.currentInterceptorIndex);
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());
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.
return proceed();
}
}
else {
// It's an interceptor, so we just invoke it: The pointcut will have
// been evaluated statically before this object was constructed.
// 通过不同的拦截器完成切面逻辑
// 也就是说执行该拦截器的切面逻辑
return ((MethodInterceptor) interceptorOrInterceptionAdvice).invoke(this);
}
}

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解下来看看这6个切面的执行逻辑：
// 0 = {ExposeInvocationInterceptor}
// 1 = {AspectJAroundAdvice}
// 2 = {MethodBeforeAdviceInterceptor}
// 3 = {AspectJAfterAdvice}
// 4 = {AfterReturningAdviceInterceptor}
// 5 = {AspectJAfterThrowingAdvice}

org.springframework.aop.interceptor.ExposeInvocationInterceptor#invoke

@Override
@Nullable
public Object invoke(MethodInvocation mi) throws Throwable {
MethodInvocation oldInvocation = invocation.get();
invocation.set(mi);
try {
return mi.proceed(); // 没有任何执行逻辑，直接调用目标方法
}
finally {
invocation.set(oldInvocation);
}
}

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org.springframework.aop.aspectj.AspectJAroundAdvice#invoke

@Override
@Nullable
public Object invoke(MethodInvocation mi) throws Throwable {
if (!(mi instanceof ProxyMethodInvocation)) {
throw new IllegalStateException("MethodInvocation is not a Spring ProxyMethodInvocation: " + mi);
}
ProxyMethodInvocation pmi = (ProxyMethodInvocation) mi;
ProceedingJoinPoint pjp = lazyGetProceedingJoinPoint(pmi);
JoinPointMatch jpm = getJoinPointMatch(pmi);
return invokeAdviceMethod(pjp, jpm, null, null); // 直接调用自定义的逻辑
}

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org.springframework.aop.framework.adapter.MethodBeforeAdviceInterceptor#invoke

@Override
@Nullable
public Object invoke(MethodInvocation mi) throws Throwable {
// 先调用自定的before方法
this.advice.before(mi.getMethod(), mi.getArguments(), mi.getThis());
// 在调用目标方法
return mi.proceed();
}

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org.springframework.aop.aspectj.AspectJAfterAdvice#invoke

@Override
@Nullable
public Object invoke(MethodInvocation mi) throws Throwable {
try {
return mi.proceed(); // 先调用目标方法
}
finally {
// 再调用自定义的after方法
// 这个方法放在了finally块中，不然会执行
invokeAdviceMethod(getJoinPointMatch(), null, null);
}
}

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org.springframework.aop.framework.adapter.AfterReturningAdviceInterceptor#invoke

@Override
@Nullable
public Object invoke(MethodInvocation mi) throws Throwable {
// 先执行目标方法
Object retVal = mi.proceed();
// 没有异常的情况下，再执行自定义的afterReturning逻辑，
this.advice.afterReturning(retVal, mi.getMethod(), mi.getArguments(), mi.getThis());
return retVal;
}

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org.springframework.aop.aspectj.AspectJAfterThrowingAdvice#invoke

@Override
@Nullable
public Object invoke(MethodInvocation mi) throws Throwable {
try {
// 先执行目标方法
return mi.proceed();
}
catch (Throwable ex) {
if (shouldInvokeOnThrowing(ex)) {
// 如果出现异常的时候，执行自定义的afterThrowing方法
invokeAdviceMethod(getJoinPointMatch(), null, ex);
}
throw ex;
}
}

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自己最好debug看看这样理解的更加深刻

使用cglib的方式创建动态代理

cglib动态代理主要是Enhancer，是创建目标类的子类来完成的动态代理。

重点关注：intercept方法

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 {
Class<?> rootClass = this.advised.getTargetClass();
Assert.state(rootClass != null, "Target class must be available for creating a CGLIB proxy");
Class<?> proxySuperClass = rootClass;
if (rootClass.getName().contains(ClassUtils.CGLIB_CLASS_SEPARATOR)) {
proxySuperClass = rootClass.getSuperclass();
Class<?>[] additionalInterfaces = rootClass.getInterfaces();
for (Class<?> additionalInterface : additionalInterfaces) {
this.advised.addInterface(additionalInterface);
}
}
// Validate the class, writing log messages as necessary.
validateClassIfNecessary(proxySuperClass, classLoader);
// 配置 CGLIB 增强器...
// Configure CGLIB Enhancer...
Enhancer enhancer = createEnhancer();
if (classLoader != null) {
enhancer.setClassLoader(classLoader);
if (classLoader instanceof SmartClassLoader &&
((SmartClassLoader) classLoader).isClassReloadable(proxySuperClass)) {
enhancer.setUseCache(false);
}
}
// 目标代理类 class com.coding.spring.aop.bean.MyAOPBean
enhancer.setSuperclass(proxySuperClass);
enhancer.setInterfaces(AopProxyUtils.completeProxiedInterfaces(this.advised));
enhancer.setNamingPolicy(SpringNamingPolicy.INSTANCE);
enhancer.setStrategy(new ClassLoaderAwareGeneratorStrategy(classLoader));
// 0 = DynamicAdvisedInterceptor
// 1 = StaticUnadvisedInterceptor
// 2 = SerializableNoOp
// 3 = StaticDispatcher
// 4 = AdvisedDispatcher
// 5 = EqualsInterceptor
// 6 = HashCodeInterceptor
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);
// 生成代理类并创建代理实例。
// 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);
}
}

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private Callback[] getCallbacks(Class<?> rootClass) throws Exception {
// Parameters used for optimization choices...
boolean exposeProxy = this.advised.isExposeProxy();
boolean isFrozen = this.advised.isFrozen();
boolean isStatic = this.advised.getTargetSource().isStatic();
// Choose an "aop" interceptor (used for AOP calls).
// AOP 回调接口 DynamicAdvisedInterceptor
// private static class DynamicAdvisedInterceptor implements MethodInterceptor, Serializable {
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;
}

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// 可以看到MethodInterceptor实现了Callback接口
public interface MethodInterceptor extends Callback {
Object intercept(Object var1, Method var2, Object[] var3, MethodProxy var4) throws Throwable;
}

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/**
* General purpose AOP callback. Used when the target is dynamic or when the
* proxy is not frozen.
*/
private static class DynamicAdvisedInterceptor implements MethodInterceptor, Serializable {
private final AdvisedSupport advised;
public DynamicAdvisedInterceptor(AdvisedSupport advised) {
this.advised = advised;
}
// CglibAopProxy.DynamicAdvisedInterceptor.intercept
// 最终创建动态代理之后，会调用到这个intercept方法
@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);
// 0 = {ExposeInvocationInterceptor}
// 1 = {AspectJAroundAdvice}
// 2 = {MethodBeforeAdviceInterceptor}
// 3 = {AspectJAfterAdvice}
// 4 = {AfterReturningAdviceInterceptor}
// 5 = {AspectJAfterThrowingAdvice}
// 获取拦截器链
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...
// 创建 CglibMethodInvocation 进行proceed()方法调用
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);
}
}
}
@Override
public boolean equals(@Nullable Object other) {
return (this == other ||
(other instanceof DynamicAdvisedInterceptor &&
this.advised.equals(((DynamicAdvisedInterceptor) other).advised)));
}
/**
* CGLIB uses this to drive proxy creation.
*/
@Override
public int hashCode() {
return this.advised.hashCode();
}
}

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org.springframework.aop.framework.CglibAopProxy.CglibMethodInvocation#proceed

@Override
@Nullable
public Object proceed() throws Throwable {
try {
// 调用 ReflectiveMethodInvocation.proceed
return super.proceed();
}
catch (RuntimeException ex) {
throw ex;
}
catch (Exception ex) {
if (ReflectionUtils.declaresException(getMethod(), ex.getClass()) ||
KotlinDetector.isKotlinType(getMethod().getDeclaringClass())) {
// Propagate original exception if declared on the target method
// (with callers expecting it). Always propagate it for Kotlin code
// since checked exceptions do not have to be explicitly declared there.
throw ex;
}
else {
// Checked exception thrown in the interceptor but not declared on the
// target method signature -> apply an UndeclaredThrowableException,
// aligned with standard JDK dynamic proxy behavior.
throw new UndeclaredThrowableException(ex);
}
}
}

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org.springframework.aop.framework.ObjenesisCglibAopProxy#createProxyClassAndInstance

@Override
protected Object createProxyClassAndInstance(Enhancer enhancer, Callback[] callbacks) {
Class<?> proxyClass = enhancer.createClass();
Object proxyInstance = null;
if (objenesis.isWorthTrying()) {
try {
// 创建代理类实例
proxyInstance = objenesis.newInstance(proxyClass, enhancer.getUseCache());
}
catch (Throwable ex) {
logger.debug("Unable to instantiate proxy using Objenesis, " +
"falling back to regular proxy construction", ex);
}
}
if (proxyInstance == null) {
// Regular instantiation via default constructor...
try {
Constructor<?> ctor = (this.constructorArgs != null ?
proxyClass.getDeclaredConstructor(this.constructorArgTypes) :
proxyClass.getDeclaredConstructor());
ReflectionUtils.makeAccessible(ctor);
proxyInstance = (this.constructorArgs != null ?
ctor.newInstance(this.constructorArgs) : ctor.newInstance());
}
catch (Throwable ex) {
throw new AopConfigException("Unable to instantiate proxy using Objenesis, " +
"and regular proxy instantiation via default constructor fails as well", ex);
}
}
// 设置 callBack 回调接口
((Factory) proxyInstance).setCallbacks(callbacks);
return proxyInstance;
}

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org.springframework.aop.framework.ReflectiveMethodInvocation#proceed

@Override
@Nullable
public Object proceed() throws Throwable {
// We start with an index of -1 and increment early.
// 所有拦截器都执行完成后，执行目标方法
if (this.currentInterceptorIndex == this.interceptorsAndDynamicMethodMatchers.size() - 1) {
return invokeJoinpoint();
}
Object interceptorOrInterceptionAdvice =
this.interceptorsAndDynamicMethodMatchers.get(++this.currentInterceptorIndex);
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());
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.
return proceed();
}
}
else {
// It's an interceptor, so we just invoke it: The pointcut will have
// been evaluated statically before this object was constructed.
// 通过不同的拦截器完成切面逻辑
// 看到这里就和jdk动态代理的逻辑是一样的了
return ((MethodInterceptor) interceptorOrInterceptionAdvice).invoke(this);
}
}

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后面的执行逻辑就和上面jdk动态代理的执行逻辑一样了。

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雕像规范像q · 发表于 2025-2-21 21:48:12

感谢楼主分享。

knuhg6435586 · 发表于 2025-4-1 06:22:26

路过，支持一下

天地交融廊 · 发表于 2025-4-15 09:45:49

感谢楼主，顶。

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spring aop底层源码执行逻辑剖析(源码解析)

目录

aop动态代理源码剖析

创建动态代理底层逻辑createProxy()

使用jdk的方式创建动态代理

使用cglib的方式创建动态代理