ProxyFactoryBean

ProxyFactoryBean

ProxyFactoryBean是spring ioc环境中创建AOP应用的底层方法，通过它完成了对AOP的封装

public Object getObject() throws BeansException {
  // 初始化通知器链
   initializeAdvisorChain();
  // 单例
   if (isSingleton()) {
      return getSingletonInstance();
   }
  // 非单例
   else {
      
      return newPrototypeInstance();
   }
}

initializeAdvisorChain

private synchronized void initializeAdvisorChain() throws AopConfigException, BeansException {
   if (this.advisorChainInitialized) {
      return;
   }

   if (!ObjectUtils.isEmpty(this.interceptorNames)) {
      if (this.beanFactory == null) {
         throw new IllegalStateException("No BeanFactory available anymore (probably due to serialization) " +
               "- cannot resolve interceptor names " + Arrays.asList(this.interceptorNames));
      }

      // Globals can't be last unless we specified a targetSource using the property...
      if (this.interceptorNames[this.interceptorNames.length - 1].endsWith(GLOBAL_SUFFIX) &&
            this.targetName == null && this.targetSource == EMPTY_TARGET_SOURCE) {
         throw new AopConfigException("Target required after globals");
      }

      // Materialize interceptor chain from bean names.
     // 添加Advisor链
      for (String name : this.interceptorNames) {
         

         if (name.endsWith(GLOBAL_SUFFIX)) {
            if (!(this.beanFactory instanceof ListableBeanFactory)) {
               throw new AopConfigException(
                     "Can only use global advisors or interceptors with a ListableBeanFactory");
            }
            addGlobalAdvisor((ListableBeanFactory) this.beanFactory,
                  name.substring(0, name.length() - GLOBAL_SUFFIX.length()));
         }

         else {
            // If we get here, we need to add a named interceptor.
            // We must check if it's a singleton or prototype.
            Object advice;
            if (this.singleton || this.beanFactory.isSingleton(name)) {
               // Add the real Advisor/Advice to the chain.
               advice = this.beanFactory.getBean(name);
            }
            else {
               // It's a prototype Advice or Advisor: replace with a prototype.
               // Avoid unnecessary creation of prototype bean just for advisor chain initialization.
               advice = new PrototypePlaceholderAdvisor(name);
            }
            addAdvisorOnChainCreation(advice, name);
         }
      }
   }

   this.advisorChainInitialized = true;
}

getSingletonInstance

private synchronized Object getSingletonInstance() {
   if (this.singletonInstance == null) {
      this.targetSource = freshTargetSource();
      if (this.autodetectInterfaces && getProxiedInterfaces().length == 0 && !isProxyTargetClass()) {
         // Rely on AOP infrastructure to tell us what interfaces to proxy.
        // 需要代理的接口
         Class<?> targetClass = getTargetClass();
         if (targetClass == null) {
            throw new FactoryBeanNotInitializedException("Cannot determine target class for proxy");
         }
        // 设置代理对象的接口
         setInterfaces(ClassUtils.getAllInterfacesForClass(targetClass, this.proxyClassLoader));
      }
      // Initialize the shared singleton instance.
      super.setFrozen(this.freezeProxy);
     // 生成代理
      this.singletonInstance = getProxy(createAopProxy());
   }
   return this.singletonInstance;
}

protected Object getProxy(AopProxy aopProxy) {
        return aopProxy.getProxy(this.proxyClassLoader);
    }

createAopProxy

protected final synchronized AopProxy createAopProxy() {
   if (!this.active) {
      activate();
   }
  // 默认使用的是DefaultAopProxyFactory
   return getAopProxyFactory().createAopProxy(this);
}

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.");
      }
     // 如果目标类是接口，则使用JdkDynamicAopProxy
      if (targetClass.isInterface() || Proxy.isProxyClass(targetClass)) {
         return new JdkDynamicAopProxy(config);
      }
     // 不是接口，使用ObjenesisCglibAopProxy
      return new ObjenesisCglibAopProxy(config);
   }
   else {
      return new JdkDynamicAopProxy(config);
   }
}

JdkDynamicAopProxy获取代理

public Object getProxy(ClassLoader classLoader) {
   
  // 获取代理接口
   Class<?>[] proxiedInterfaces = AopProxyUtils.completeProxiedInterfaces(this.advised, true);
   findDefinedEqualsAndHashCodeMethods(proxiedInterfaces);
   return Proxy.newProxyInstance(classLoader, proxiedInterfaces, this);
}

ObjenesisCglibAopProxy获取代理

public Object getProxy(ClassLoader classLoader) {
   

   try {
     // 获取需要代理的类对象
      Class<?> rootClass = this.advised.getTargetClass();
      Assert.state(rootClass != null, "Target class must be available for creating a CGLIB proxy");

      Class<?> proxySuperClass = rootClass;
      if (ClassUtils.isCglibProxyClass(rootClass)) {
         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);

      // Configure CGLIB Enhancer...
     // 创建Enhancer
      Enhancer enhancer = createEnhancer();
      if (classLoader != null) {
         enhancer.setClassLoader(classLoader);
         if (classLoader instanceof SmartClassLoader &&
               ((SmartClassLoader) classLoader).isClassReloadable(proxySuperClass)) {
            enhancer.setUseCache(false);
         }
      }
     // 设置Enhancer对象
      enhancer.setSuperclass(proxySuperClass);
      enhancer.setInterfaces(AopProxyUtils.completeProxiedInterfaces(this.advised));
      enhancer.setNamingPolicy(SpringNamingPolicy.INSTANCE);
      enhancer.setStrategy(new ClassLoaderAwareUndeclaredThrowableStrategy(classLoader));

      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 ex) {
      throw new AopConfigException("Could not generate CGLIB subclass of class [" +
            this.advised.getTargetClass() + "]: " +
            "Common causes of this problem include using a final class or a non-visible class",
            ex);
   }
   catch (IllegalArgumentException ex) {
      throw new AopConfigException("Could not generate CGLIB subclass of class [" +
            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);
   }
}