Spring及Spring boot 第二章 AOP 源码 AopProxy系列

CglibAopProxy

getProxy获得Proxy

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;
            int x;
            if (rootClass.getName().contains("$$")) {
                proxySuperClass = rootClass.getSuperclass();
                Class<?>[] additionalInterfaces = rootClass.getInterfaces();
                Class[] var5 = additionalInterfaces;
                int var6 = additionalInterfaces.length;

                for(x = 0; x < var6; ++x) {
                    Class<?> additionalInterface = var5[x];
                    this.advised.addInterface(additionalInterface);
                }
            }

            this.validateClassIfNecessary(proxySuperClass, classLoader);
            Enhancer enhancer = this.createEnhancer();
            if (classLoader != null) {
                enhancer.setClassLoader(classLoader);
                if (classLoader instanceof SmartClassLoader && ((SmartClassLoader)classLoader).isClassReloadable(proxySuperClass)) {
                    enhancer.setUseCache(false);
                }
            }

            enhancer.setSuperclass(proxySuperClass);
            enhancer.setInterfaces(AopProxyUtils.completeProxiedInterfaces(this.advised));
            enhancer.setNamingPolicy(SpringNamingPolicy.INSTANCE);
            enhancer.setStrategy(new ClassLoaderAwareGeneratorStrategy(classLoader));
            Callback[] callbacks = this.getCallbacks(rootClass);
            Class<?>[] types = new Class[callbacks.length];

            for(x = 0; x < types.length; ++x) {
                types[x] = callbacks[x].getClass();
            }

            enhancer.setCallbackFilter(new CglibAopProxy.ProxyCallbackFilter(this.advised.getConfigurationOnlyCopy(), this.fixedInterceptorMap, this.fixedInterceptorOffset));
            enhancer.setCallbackTypes(types);
            return this.createProxyClassAndInstance(enhancer, callbacks);
        } catch (IllegalArgumentException | CodeGenerationException var9) {
            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", var9);
        } catch (Throwable var10) {
            throw new AopConfigException("Unexpected AOP exception", var10);
        }
    }

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0：进行 AOP 代理的通用拦截器【重点关注】
1：执行目标方法的拦截器
2：空的 Callback 对象，例如 finalize() 方法，不需要进行任何处理
3：目标对象调度器，用于获取目标对象
4：配置管理器的调度器，会返回一个 AdvisedSupport 对象
5：处理 equals(Object) 方法的拦截器
6：处理 hashCode() 方法的拦截器

getCallbacks

	private Callback[] getCallbacks(Class<?> rootClass) throws Exception {
		// Parameters used for optimization choices...
		boolean exposeProxy = this.advised.isExposeProxy();
		boolean isFrozen = this.advised.isFrozen();
		boolean isStatic = this.advised.getTargetSource().isStatic();

		// Choose an "aop" interceptor (used for AOP calls).
		Callback aopInterceptor = new DynamicAdvisedInterceptor(this.advised);

		// Choose a "straight to target" interceptor. (used for calls that are
		// unadvised but can return this). May be required to expose the proxy.
		Callback targetInterceptor;
		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()));
		}

		// Choose a "direct to target" dispatcher (used for
		// unadvised calls to static targets that cannot return this).
		Callback targetDispatcher = (isStatic ?
				new StaticDispatcher(this.advised.getTargetSource().getTarget()) : new SerializableNoOp());

		Callback[] mainCallbacks = new Callback[] {
				aopInterceptor,  // for normal advice
				targetInterceptor,  // invoke target without considering advice, if optimized
				new SerializableNoOp(),  // no override for methods mapped to this
				targetDispatcher, this.advisedDispatcher,
				new EqualsInterceptor(this.advised),
				new HashCodeInterceptor(this.advised)
		};

		Callback[] callbacks;

		// If the target is a static one and the advice chain is frozen,
		// then we can make some optimizations by sending the AOP calls
		// direct to the target using the fixed chain for that method.
		if (isStatic && isFrozen) {
			Method[] methods = rootClass.getMethods();
			Callback[] fixedCallbacks = new Callback[methods.length];
			this.fixedInterceptorMap = CollectionUtils.newHashMap(methods.length);

			// TODO: small memory optimization here (can skip creation for methods with no advice)
			for (int x = 0; x < methods.length; x++) {
				Method method = methods[x];
				List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, rootClass);
				fixedCallbacks[x] = new FixedChainStaticTargetInterceptor(
						chain, this.advised.getTargetSource().getTarget(), this.advised.getTargetClass());
				this.fixedInterceptorMap.put(method, x);
			}

			// Now copy both the callbacks from mainCallbacks
			// and fixedCallbacks into the callbacks array.
			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;
		}
		else {
			callbacks = mainCallbacks;
		}
		return callbacks;
	}
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