Spring框架学习[创建AOP代理对象并对目标对象切面拦截] - JAVA

System.arraycopy(mainCallbacks, 0, callbacks, 0, mainCallbacks.length); System.arraycopy(fixedCallbacks, 0, callbacks, mainCallbacks.length, fixedCallbacks.length); this.fixedInterceptorOffset = mainCallbacks.length; } //如果目标不是静态的，或者通知链不被冻结，则使用AOP主要的通知 else { callbacks = mainCallbacks; } return callbacks; }

//通过CGLIB方式创建AOP代理对象public Object getProxy(ClassLoader classLoader) {		if (logger.isDebugEnabled()) {			logger.debug("Creating CGLIB2 proxy: target source is " + this.advised.getTargetSource());		}		try {			//从代理创建辅助类中获取在IoC容器中配置的目标对象			Class rootClass = this.advised.getTargetClass();			Assert.state(rootClass != null, "Target class must be available for creating a CGLIB proxy");			//将目标对象本身做为自己的基类			Class proxySuperClass = rootClass;			//检查获取到的目标类是否是CGLIB产生的			if (AopUtils.isCglibProxyClass(rootClass)) {				//如果目标类是有CGLIB产生的，获取目标类的基类				proxySuperClass = rootClass.getSuperclass();				//获取目标类的接口				Class[] additionalInterfaces = rootClass.getInterfaces();				//将目标类的接口添加到容器AOP代理创建辅助类的配置中				for (Class additionalInterface : additionalInterfaces) {					this.advised.addInterface(additionalInterface);				}			}			//校验代理基类			validateClassIfNecessary(proxySuperClass);			//配置CGLIB的Enhancer类，Enhancer是CGLIB中的主要操作类			Enhancer enhancer = createEnhancer();			if (classLoader != null) {				enhancer.setClassLoader(classLoader);				if (classLoader instanceof SmartClassLoader &&						((SmartClassLoader) classLoader).isClassReloadable(proxySuperClass)) {					enhancer.setUseCache(false);				}			}			//设置enhancer的基类			enhancer.setSuperclass(proxySuperClass);			enhancer.setStrategy(new UndeclaredThrowableStrategy(UndeclaredThrowableException.class));	//设置enhancer的接口	enhancer.setInterfaces(AopProxyUtils.completeProxiedInterfaces(this.advised));			enhancer.setInterceptDuringConstruction(false);			//设置enhancer的回调方法			Callback[] callbacks = getCallbacks(rootClass);			enhancer.setCallbacks(callbacks);			//将通知器中配置作为enhancer的方法过滤			enhancer.setCallbackFilter(new ProxyCallbackFilter(					this.advised.getConfigurationOnlyCopy(), this.fixedInterceptorMap, this.fixedInterceptorOffset));			Class[] types = new Class[callbacks.length];			for (int x = 0; x < types.length; x++) {				types[x] = callbacks[x].getClass();			}			//设置enhancer的回调类型			enhancer.setCallbackTypes(types);			//创建代理对象			Object proxy;			if (this.constructorArgs != null) {				proxy = enhancer.create(this.constructorArgTypes, this.constructorArgs);			}			else {				proxy = enhancer.create();			}			return proxy;		}		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 (Exception ex) {			// TargetSource.getTarget() failed			throw new AopConfigException("Unexpected AOP exception", ex);		}	}//获取给定类的回调通知 private Callback[] getCallbacks(Class rootClass) throws Exception {		//优化参数		boolean exposeProxy = this.advised.isExposeProxy();		boolean isFrozen = this.advised.isFrozen();		boolean isStatic = this.advised.getTargetSource().isStatic();		//根据AOP配置创建一个动态通知拦截器，CGLIB创建的动态代理会自动调用		//DynamicAdvisedInterceptor类的intercept方法对目标对象进行拦截处理		Callback aopInterceptor = new DynamicAdvisedInterceptor(this.advised);		Callback targetInterceptor;		//根据是否暴露代理，创建直接应用目标的通知		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());		}		// 创建目标分发器		Callback targetDispatcher = isStatic  				new StaticDispatcher(this.advised.getTargetSource().getTarget()) : new SerializableNoOp();		Callback[] mainCallbacks = new Callback[]{			aopInterceptor, //普通通知			targetInterceptor, // 如果优化则不考虑配置的通知			new SerializableNoOp(), //没有被覆盖的方法			targetDispatcher, this.advisedDispatcher,			new EqualsInterceptor(this.advised),			new HashCodeInterceptor(this.advised)		};		Callback[] callbacks;		//如果目标是静态的，并且通知链被冻结，则使用优化AOP调用，直接对方法使用//固定的通知链		if (isStatic && isFrozen) {			Method[] methods = rootClass.getMethods();			Callback[] fixedCallbacks = new Callback[methods.length];			this.fixedInterceptorMap = new HashMap<String, Integer>(methods.length);			for (int x = 0; x < methods.length; x++) {				List<cke:Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(methods[x], rootClass);				fixedCallbacks[x] = new FixedChainStaticTargetInterceptor(						chain, this.advised.getTargetSource().getTarget(), this.advised.getTargetClass());				this.fixedInterceptorMap.put(methods[x].toString(), x);			}			//将固定回调和主要回调拷贝到回调数组中			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;		}		//如果目标不是静态的，或者通知链不被冻结，则使用AOP主要的通知		else {			callbacks = mainCallbacks;		}		return callbacks;	}

通过上面对CGLIB创建代理和获取回答通知的源码分析，我们了解到CGLIB在获取代理的通知时，会创建DynamicAdvisedInterceptor类，当应用调用目标对象的方法时，不是直接调用目标对象，而是通过CGLIB创建的代理对象来调用目标对象，在调用目标对象的方法时，触发DynamicAdvisedInterceptor的intercept回调方法对目标对象进行处理，CGLIB回调拦截器链的源码如下：

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Spring框架学习[创建AOP代理对象并对目标对象切面拦截](十)