spring源码分析之——spring aop代理实现细节

前面分析了spring aop的实现原理。为了突出整个流程的清晰，其中有些细节部分没有详细分析。

现在就分析一下aop生成代理对象的细节。言乘上文,spring aop 生成代理对象是在

AbstractAutoProxyCreator的如下方法中：

protected Object createProxy(
			Class<?> beanClass, String beanName, Object[] specificInterceptors, TargetSource targetSource) {

		ProxyFactory proxyFactory = new ProxyFactory();
		// Copy our properties (proxyTargetClass etc) inherited from ProxyConfig.
		proxyFactory.copyFrom(this);

		if (!shouldProxyTargetClass(beanClass, beanName)) {
			// Must allow for introductions; can't just set interfaces to
			// the target's interfaces only.
			Class<?>[] targetInterfaces = ClassUtils.getAllInterfacesForClass(beanClass, this.proxyClassLoader);
			for (Class<?> targetInterface : targetInterfaces) {
				proxyFactory.addInterface(targetInterface);
			}
		}

		Advisor[] advisors = buildAdvisors(beanName, specificInterceptors);
		for (Advisor advisor : advisors) {
			proxyFactory.addAdvisor(advisor);
		}

		proxyFactory.setTargetSource(targetSource);
		customizeProxyFactory(proxyFactory);

		proxyFactory.setFrozen(this.freezeProxy);
		if (advisorsPreFiltered()) {
			proxyFactory.setPreFiltered(true);
		}

		return proxyFactory.getProxy(this.proxyClassLoader);
	}

   从上面可以看出，如果设置了proxyTargetClass，那么proxyFactory就不调用addInterface.

   跟踪一下最后代码，最后实际调用了了DefaultAopProxyFactory的createAopProxy方法，代码如下：

 

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()) {
				return new JdkDynamicAopProxy(config);
			}
			if (!cglibAvailable) {
				throw new AopConfigException(
						"Cannot proxy target class because CGLIB2 is not available. " +
						"Add CGLIB to the class path or specify proxy interfaces.");
			}
			return CglibProxyFactory.createCglibProxy(config);
		}
		else {
			return new JdkDynamicAopProxy(config);
		}
	}

   这段代码的意义很明确。如果设置了proxyTargetClass或者根本没有接口，那么就

   使用CglibProxyFactory生成代理。否则使用JdkDynamicAopProxy。

   这两种代理方式的实现细节在此不作分析。