Spring 5.x 源码之旅四十八AOP代理细节三JdkDynamicAopProxy和CglibAopProxy

JdkDynamicAopProxy的getProxy

主要是JdkDynamicAopProxy在代理前还有一些事情要说下：

AopProxyUtils的completeProxiedInterfaces

这里说白了就是增加一些其他的接口SpringProxy，DecoratingProxy，Advised。

static Class<?>[] completeProxiedInterfaces(AdvisedSupport advised, boolean decoratingProxy) {
		Class<?>[] specifiedInterfaces = advised.getProxiedInterfaces();
		if (specifiedInterfaces.length == 0) {
			// No user-specified interfaces: check whether target class is an interface.
			Class<?> targetClass = advised.getTargetClass();
			if (targetClass != null) {
				if (targetClass.isInterface()) {
					advised.setInterfaces(targetClass);
				}
				else if (Proxy.isProxyClass(targetClass)) {
					advised.setInterfaces(targetClass.getInterfaces());
				}
				specifiedInterfaces = advised.getProxiedInterfaces();
			}
		}
		boolean addSpringProxy = !advised.isInterfaceProxied(SpringProxy.class);
		boolean addAdvised = !advised.isOpaque() && !advised.isInterfaceProxied(Advised.class);
		boolean addDecoratingProxy = (decoratingProxy && !advised.isInterfaceProxied(DecoratingProxy.class));
		int nonUserIfcCount = 0;
		if (addSpringProxy) {//需要添加SpringProxy接口
			nonUserIfcCount++;
		}
		if (addAdvised) {//需要添加通知
			nonUserIfcCount++;
		}
		if (addDecoratingProxy) {//需要添加DecoratingProxy接口
			nonUserIfcCount++;
		}
		Class<?>[] proxiedInterfaces = new Class<?>[specifiedInterfaces.length + nonUserIfcCount];
		System.arraycopy(specifiedInterfaces, 0, proxiedInterfaces, 0, specifiedInterfaces.length);
		int index = specifiedInterfaces.length;
		if (addSpringProxy) {
			proxiedInterfaces[index] = SpringProxy.class;
			index++;
		}
		if (addAdvised) {
			proxiedInterfaces[index] = Advised.class;
			index++;
		}
		if (addDecoratingProxy) {
			proxiedInterfaces[index] = DecoratingProxy.class;
		}
		return proxiedInterfaces;
	}

CglibAopProxy的getProxy

就是CGLIB的基本用法，创建增强器，拦截器，设置父类等

@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)) {//类名是否包含CGLIB分隔符
				proxySuperClass = rootClass.getSuperclass();
				Class<?>[] additionalInterfaces = rootClass.getInterfaces();//获得原始父类的接口
				for (Class<?> additionalInterface : additionalInterfaces) {
					this.advised.addInterface(additionalInterface);
				}
			}
			//验证修饰符和方法修饰符
			// Validate the class, writing log messages as necessary.
			validateClassIfNecessary(proxySuperClass, classLoader);

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

ObjenesisCglibAopProxy的createProxyClassAndInstance

生成代理类，然后用objenesis生成实例。

@Override
	protected Object createProxyClassAndInstance(Enhancer enhancer, Callback[] callbacks) {
		Class<?> proxyClass = enhancer.createClass();
		Object proxyInstance = null;

		if (objenesis.isWorthTrying()) {
			try {
				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);
			}
		}

		((Factory) proxyInstance).setCallbacks(callbacks);
		return proxyInstance;
	}

最后还会设置一些回调器：

了解到这里就差不多知道是怎么生成AOP代理了，接下去就看看哪些方法是怎么执行的吧。

好了，今天就到这里了，希望对学习理解有帮助，大神看见勿喷，仅为自己的学习理解，能力有限，请多包涵。