Spring-11 AOP JDK & CGLIB 动态代理详解

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ProxyFactory & AopProxyFactory & AopProxy & 代理对象之间的关系

ProxyFactory 中的重要属性有 targetSource 封装了目标对象, interfaces 目标对象类型的接口 , advisors 封装了切面和连接点信息。在创建代理对象的过程中会将 ProxyFactory 对象层层传递以保留 AOP 的相关配置信息。

JDK 动态代理

jdk 代理使用的是 JdkDynamicAopProxy 创建的。JdkDynamicAopProxy 本身就是 InvocationHandler 的实现。在创建代理时就是使用 jdk Proxy 创建代理对象。

@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);
         try {
            retVal = methodProxy.invoke(target, argsToUse);
         }
         catch (CodeGenerationException ex) {
            CglibMethodInvocation.logFastClassGenerationFailure(method);
            retVal = AopUtils.invokeJoinpointUsingReflection(target, method, argsToUse);
         }
      }
      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);
      }
   }
}

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