https://github.com/spring-projects/spring-framework: Spring Context (Spring IO)
  • Juergen Hoeller 
/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.context.annotation;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.lang.reflect.Proxy;
import java.util.Arrays;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.aop.scope.ScopedProxyFactoryBean;
import org.springframework.asm.Type;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.beans.factory.support.SimpleInstantiationStrategy;
import org.springframework.cglib.core.ClassGenerator;
import org.springframework.cglib.core.Constants;
import org.springframework.cglib.core.DefaultGeneratorStrategy;
import org.springframework.cglib.core.SpringNamingPolicy;
import org.springframework.cglib.proxy.Callback;
import org.springframework.cglib.proxy.CallbackFilter;
import org.springframework.cglib.proxy.Enhancer;
import org.springframework.cglib.proxy.Factory;
import org.springframework.cglib.proxy.MethodInterceptor;
import org.springframework.cglib.proxy.MethodProxy;
import org.springframework.cglib.proxy.NoOp;
import org.springframework.cglib.transform.ClassEmitterTransformer;
import org.springframework.cglib.transform.TransformingClassGenerator;
import org.springframework.lang.Nullable;
import org.springframework.objenesis.ObjenesisException;
import org.springframework.objenesis.SpringObjenesis;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.ObjectUtils;
import org.springframework.util.ReflectionUtils;


Enhances Configuration classes by generating a CGLIB subclass which interacts with the Spring container to respect bean scoping semantics for @Bean methods. Each such @Bean method will be overridden in the generated subclass, only delegating to the actual @Bean method implementation if the container actually requests the construction of a new instance. Otherwise, a call to such an @Bean method serves as a reference back to the container, obtaining the corresponding bean by name. 
Author:Chris Beams, Juergen Hoeller
See Also:
Since:3.0
/**
 * Enhances {@link Configuration} classes by generating a CGLIB subclass which
 * interacts with the Spring container to respect bean scoping semantics for
 * {@code @Bean} methods. Each such {@code @Bean} method will be overridden in
 * the generated subclass, only delegating to the actual {@code @Bean} method
 * implementation if the container actually requests the construction of a new
 * instance. Otherwise, a call to such an {@code @Bean} method serves as a
 * reference back to the container, obtaining the corresponding bean by name.
 *
 * @author Chris Beams
 * @author Juergen Hoeller
 * @since 3.0
 * @see #enhance
 * @see ConfigurationClassPostProcessor
 */
class ConfigurationClassEnhancer {

	// The callbacks to use. Note that these callbacks must be stateless.
	private static final Callback[] CALLBACKS = new Callback[] {
			new BeanMethodInterceptor(),
			new BeanFactoryAwareMethodInterceptor(),
			NoOp.INSTANCE
	};

	private static final ConditionalCallbackFilter CALLBACK_FILTER = new ConditionalCallbackFilter(CALLBACKS);

	private static final String BEAN_FACTORY_FIELD = "$$beanFactory";


	private static final Log logger = LogFactory.getLog(ConfigurationClassEnhancer.class);

	private static final SpringObjenesis objenesis = new SpringObjenesis();


	
Loads the specified class and generates a CGLIB subclass of it equipped with
container-aware callbacks capable of respecting scoping and other bean semantics.

Returns:the enhanced subclass
/**
	 * Loads the specified class and generates a CGLIB subclass of it equipped with
	 * container-aware callbacks capable of respecting scoping and other bean semantics.
	 * @return the enhanced subclass
	 */
	public Class<?> enhance(Class<?> configClass, @Nullable ClassLoader classLoader) {
		if (EnhancedConfiguration.class.isAssignableFrom(configClass)) {
			if (logger.isDebugEnabled()) {
				logger.debug(String.format("Ignoring request to enhance %s as it has " +
						"already been enhanced. This usually indicates that more than one " +
						"ConfigurationClassPostProcessor has been registered (e.g. via " +
						"<context:annotation-config>). This is harmless, but you may " +
						"want check your configuration and remove one CCPP if possible",
						configClass.getName()));
			}
			return configClass;
		}
		Class<?> enhancedClass = createClass(newEnhancer(configClass, classLoader));
		if (logger.isTraceEnabled()) {
			logger.trace(String.format("Successfully enhanced %s; enhanced class name is: %s",
					configClass.getName(), enhancedClass.getName()));
		}
		return enhancedClass;
	}

	
Creates a new CGLIB Enhancer instance. 
/**
	 * Creates a new CGLIB {@link Enhancer} instance.
	 */
	private Enhancer newEnhancer(Class<?> configSuperClass, @Nullable ClassLoader classLoader) {
		Enhancer enhancer = new Enhancer();
		enhancer.setSuperclass(configSuperClass);
		enhancer.setInterfaces(new Class<?>[] {EnhancedConfiguration.class});
		enhancer.setUseFactory(false);
		enhancer.setNamingPolicy(SpringNamingPolicy.INSTANCE);
		enhancer.setStrategy(new BeanFactoryAwareGeneratorStrategy(classLoader));
		enhancer.setCallbackFilter(CALLBACK_FILTER);
		enhancer.setCallbackTypes(CALLBACK_FILTER.getCallbackTypes());
		return enhancer;
	}

	
Uses enhancer to generate a subclass of superclass,
ensuring that callbacks are registered for the new subclass.

/**
	 * Uses enhancer to generate a subclass of superclass,
	 * ensuring that callbacks are registered for the new subclass.
	 */
	private Class<?> createClass(Enhancer enhancer) {
		Class<?> subclass = enhancer.createClass();
		// Registering callbacks statically (as opposed to thread-local)
		// is critical for usage in an OSGi environment (SPR-5932)...
		Enhancer.registerStaticCallbacks(subclass, CALLBACKS);
		return subclass;
	}


	
Marker interface to be implemented by all @Configuration CGLIB subclasses. Facilitates idempotent behavior for ConfigurationClassEnhancer.enhance through checking to see if candidate classes are already assignable to it, e.g. have already been enhanced. 
Also extends BeanFactoryAware, as all enhanced @Configuration classes require access to the BeanFactory that created them. 
Note that this interface is intended for framework-internal use only, however
must remain public in order to allow access to subclasses generated from other
packages (i.e. user code).

/**
	 * Marker interface to be implemented by all @Configuration CGLIB subclasses.
	 * Facilitates idempotent behavior for {@link ConfigurationClassEnhancer#enhance}
	 * through checking to see if candidate classes are already assignable to it, e.g.
	 * have already been enhanced.
	 * <p>Also extends {@link BeanFactoryAware}, as all enhanced {@code @Configuration}
	 * classes require access to the {@link BeanFactory} that created them.
	 * <p>Note that this interface is intended for framework-internal use only, however
	 * must remain public in order to allow access to subclasses generated from other
	 * packages (i.e. user code).
	 */
	public interface EnhancedConfiguration extends BeanFactoryAware {
	}


	
Conditional Callback. 
See Also:
/**
	 * Conditional {@link Callback}.
	 * @see ConditionalCallbackFilter
	 */
	private interface ConditionalCallback extends Callback {

		boolean isMatch(Method candidateMethod);
	}


	
A CallbackFilter that works by interrogating Callbacks in the order that they are defined via ConditionalCallback. 
/**
	 * A {@link CallbackFilter} that works by interrogating {@link Callback Callbacks} in the order
	 * that they are defined via {@link ConditionalCallback}.
	 */
	private static class ConditionalCallbackFilter implements CallbackFilter {

		private final Callback[] callbacks;

		private final Class<?>[] callbackTypes;

		public ConditionalCallbackFilter(Callback[] callbacks) {
			this.callbacks = callbacks;
			this.callbackTypes = new Class<?>[callbacks.length];
			for (int i = 0; i < callbacks.length; i++) {
				this.callbackTypes[i] = callbacks[i].getClass();
			}
		}

		@Override
		public int accept(Method method) {
			for (int i = 0; i < this.callbacks.length; i++) {
				Callback callback = this.callbacks[i];
				if (!(callback instanceof ConditionalCallback) || ((ConditionalCallback) callback).isMatch(method)) {
					return i;
				}
			}
			throw new IllegalStateException("No callback available for method " + method.getName());
		}

		public Class<?>[] getCallbackTypes() {
			return this.callbackTypes;
		}
	}


	
Custom extension of CGLIB's DefaultGeneratorStrategy, introducing a BeanFactory field. Also exposes the application ClassLoader as thread context ClassLoader for the time of class generation (in order for ASM to pick it up when doing common superclass resolution). 
/**
	 * Custom extension of CGLIB's DefaultGeneratorStrategy, introducing a {@link BeanFactory} field.
	 * Also exposes the application ClassLoader as thread context ClassLoader for the time of
	 * class generation (in order for ASM to pick it up when doing common superclass resolution).
	 */
	private static class BeanFactoryAwareGeneratorStrategy extends DefaultGeneratorStrategy {

		@Nullable
		private final ClassLoader classLoader;

		public BeanFactoryAwareGeneratorStrategy(@Nullable ClassLoader classLoader) {
			this.classLoader = classLoader;
		}

		@Override
		protected ClassGenerator transform(ClassGenerator cg) throws Exception {
			ClassEmitterTransformer transformer = new ClassEmitterTransformer() {
				@Override
				public void end_class() {
					declare_field(Constants.ACC_PUBLIC, BEAN_FACTORY_FIELD, Type.getType(BeanFactory.class), null);
					super.end_class();
				}
			};
			return new TransformingClassGenerator(cg, transformer);
		}

		@Override
		public byte[] generate(ClassGenerator cg) throws Exception {
			if (this.classLoader == null) {
				return super.generate(cg);
			}

			Thread currentThread = Thread.currentThread();
			ClassLoader threadContextClassLoader;
			try {
				threadContextClassLoader = currentThread.getContextClassLoader();
			}
			catch (Throwable ex) {
				// Cannot access thread context ClassLoader - falling back...
				return super.generate(cg);
			}

			boolean overrideClassLoader = !this.classLoader.equals(threadContextClassLoader);
			if (overrideClassLoader) {
				currentThread.setContextClassLoader(this.classLoader);
			}
			try {
				return super.generate(cg);
			}
			finally {
				if (overrideClassLoader) {
					// Reset original thread context ClassLoader.
					currentThread.setContextClassLoader(threadContextClassLoader);
				}
			}
		}
	}


	
Intercepts the invocation of any BeanFactoryAware.setBeanFactory(BeanFactory) on @Configuration class instances for the purpose of recording the BeanFactory. 
See Also:
/**
	 * Intercepts the invocation of any {@link BeanFactoryAware#setBeanFactory(BeanFactory)} on
	 * {@code @Configuration} class instances for the purpose of recording the {@link BeanFactory}.
	 * @see EnhancedConfiguration
	 */
	private static class BeanFactoryAwareMethodInterceptor implements MethodInterceptor, ConditionalCallback {

		@Override
		@Nullable
		public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy) throws Throwable {
			Field field = ReflectionUtils.findField(obj.getClass(), BEAN_FACTORY_FIELD);
			Assert.state(field != null, "Unable to find generated BeanFactory field");
			field.set(obj, args[0]);

			// Does the actual (non-CGLIB) superclass implement BeanFactoryAware?
			// If so, call its setBeanFactory() method. If not, just exit.
			if (BeanFactoryAware.class.isAssignableFrom(ClassUtils.getUserClass(obj.getClass().getSuperclass()))) {
				return proxy.invokeSuper(obj, args);
			}
			return null;
		}

		@Override
		public boolean isMatch(Method candidateMethod) {
			return isSetBeanFactory(candidateMethod);
		}

		public static boolean isSetBeanFactory(Method candidateMethod) {
			return (candidateMethod.getName().equals("setBeanFactory") &&
					candidateMethod.getParameterCount() == 1 &&
					BeanFactory.class == candidateMethod.getParameterTypes()[0] &&
					BeanFactoryAware.class.isAssignableFrom(candidateMethod.getDeclaringClass()));
		}
	}


	
Intercepts the invocation of any Bean-annotated methods in order to ensure proper handling of bean semantics such as scoping and AOP proxying. 
See Also:
/**
	 * Intercepts the invocation of any {@link Bean}-annotated methods in order to ensure proper
	 * handling of bean semantics such as scoping and AOP proxying.
	 * @see Bean
	 * @see ConfigurationClassEnhancer
	 */
	private static class BeanMethodInterceptor implements MethodInterceptor, ConditionalCallback {

		
Enhance a @Bean method to check the supplied BeanFactory for the existence of this bean object. 
Throws:
  • Throwable – as a catch-all for any exception that may be thrown when invoking the super implementation of the proxied method i.e., the actual @Bean method
/**
		 * Enhance a {@link Bean @Bean} method to check the supplied BeanFactory for the
		 * existence of this bean object.
		 * @throws Throwable as a catch-all for any exception that may be thrown when invoking the
		 * super implementation of the proxied method i.e., the actual {@code @Bean} method
		 */
		@Override
		@Nullable
		public Object intercept(Object enhancedConfigInstance, Method beanMethod, Object[] beanMethodArgs,
					MethodProxy cglibMethodProxy) throws Throwable {

			ConfigurableBeanFactory beanFactory = getBeanFactory(enhancedConfigInstance);
			String beanName = BeanAnnotationHelper.determineBeanNameFor(beanMethod);

			// Determine whether this bean is a scoped-proxy
			if (BeanAnnotationHelper.isScopedProxy(beanMethod)) {
				String scopedBeanName = ScopedProxyCreator.getTargetBeanName(beanName);
				if (beanFactory.isCurrentlyInCreation(scopedBeanName)) {
					beanName = scopedBeanName;
				}
			}

			// To handle the case of an inter-bean method reference, we must explicitly check the
			// container for already cached instances.

			// First, check to see if the requested bean is a FactoryBean. If so, create a subclass
			// proxy that intercepts calls to getObject() and returns any cached bean instance.
			// This ensures that the semantics of calling a FactoryBean from within @Bean methods
			// is the same as that of referring to a FactoryBean within XML. See SPR-6602.
			if (factoryContainsBean(beanFactory, BeanFactory.FACTORY_BEAN_PREFIX + beanName) &&
					factoryContainsBean(beanFactory, beanName)) {
				Object factoryBean = beanFactory.getBean(BeanFactory.FACTORY_BEAN_PREFIX + beanName);
				if (factoryBean instanceof ScopedProxyFactoryBean) {
					// Scoped proxy factory beans are a special case and should not be further proxied
				}
				else {
					// It is a candidate FactoryBean - go ahead with enhancement
					return enhanceFactoryBean(factoryBean, beanMethod.getReturnType(), beanFactory, beanName);
				}
			}

			if (isCurrentlyInvokedFactoryMethod(beanMethod)) {
				// The factory is calling the bean method in order to instantiate and register the bean
				// (i.e. via a getBean() call) -> invoke the super implementation of the method to actually
				// create the bean instance.
				if (logger.isInfoEnabled() &&
						BeanFactoryPostProcessor.class.isAssignableFrom(beanMethod.getReturnType())) {
					logger.info(String.format("@Bean method %s.%s is non-static and returns an object " +
									"assignable to Spring's BeanFactoryPostProcessor interface. This will " +
									"result in a failure to process annotations such as @Autowired, " +
									"@Resource and @PostConstruct within the method's declaring " +
									"@Configuration class. Add the 'static' modifier to this method to avoid " +
									"these container lifecycle issues; see @Bean javadoc for complete details.",
							beanMethod.getDeclaringClass().getSimpleName(), beanMethod.getName()));
				}
				return cglibMethodProxy.invokeSuper(enhancedConfigInstance, beanMethodArgs);
			}

			return resolveBeanReference(beanMethod, beanMethodArgs, beanFactory, beanName);
		}

		private Object resolveBeanReference(Method beanMethod, Object[] beanMethodArgs,
				ConfigurableBeanFactory beanFactory, String beanName) {

			// The user (i.e. not the factory) is requesting this bean through a call to
			// the bean method, direct or indirect. The bean may have already been marked
			// as 'in creation' in certain autowiring scenarios; if so, temporarily set
			// the in-creation status to false in order to avoid an exception.
			boolean alreadyInCreation = beanFactory.isCurrentlyInCreation(beanName);
			try {
				if (alreadyInCreation) {
					beanFactory.setCurrentlyInCreation(beanName, false);
				}
				boolean useArgs = !ObjectUtils.isEmpty(beanMethodArgs);
				if (useArgs && beanFactory.isSingleton(beanName)) {
					// Stubbed null arguments just for reference purposes,
					// expecting them to be autowired for regular singleton references?
					// A safe assumption since @Bean singleton arguments cannot be optional...
					for (Object arg : beanMethodArgs) {
						if (arg == null) {
							useArgs = false;
							break;
						}
					}
				}
				Object beanInstance = (useArgs ? beanFactory.getBean(beanName, beanMethodArgs) :
						beanFactory.getBean(beanName));
				if (!ClassUtils.isAssignableValue(beanMethod.getReturnType(), beanInstance)) {
					// Detect package-protected NullBean instance through equals(null) check
					if (beanInstance.equals(null)) {
						if (logger.isDebugEnabled()) {
							logger.debug(String.format("@Bean method %s.%s called as bean reference " +
									"for type [%s] returned null bean; resolving to null value.",
									beanMethod.getDeclaringClass().getSimpleName(), beanMethod.getName(),
									beanMethod.getReturnType().getName()));
						}
						beanInstance = null;
					}
					else {
						String msg = String.format("@Bean method %s.%s called as bean reference " +
								"for type [%s] but overridden by non-compatible bean instance of type [%s].",
								beanMethod.getDeclaringClass().getSimpleName(), beanMethod.getName(),
								beanMethod.getReturnType().getName(), beanInstance.getClass().getName());
						try {
							BeanDefinition beanDefinition = beanFactory.getMergedBeanDefinition(beanName);
							msg += " Overriding bean of same name declared in: " + beanDefinition.getResourceDescription();
						}
						catch (NoSuchBeanDefinitionException ex) {
							// Ignore - simply no detailed message then.
						}
						throw new IllegalStateException(msg);
					}
				}
				Method currentlyInvoked = SimpleInstantiationStrategy.getCurrentlyInvokedFactoryMethod();
				if (currentlyInvoked != null) {
					String outerBeanName = BeanAnnotationHelper.determineBeanNameFor(currentlyInvoked);
					beanFactory.registerDependentBean(beanName, outerBeanName);
				}
				return beanInstance;
			}
			finally {
				if (alreadyInCreation) {
					beanFactory.setCurrentlyInCreation(beanName, true);
				}
			}
		}

		@Override
		public boolean isMatch(Method candidateMethod) {
			return (candidateMethod.getDeclaringClass() != Object.class &&
					!BeanFactoryAwareMethodInterceptor.isSetBeanFactory(candidateMethod) &&
					BeanAnnotationHelper.isBeanAnnotated(candidateMethod));
		}

		private ConfigurableBeanFactory getBeanFactory(Object enhancedConfigInstance) {
			Field field = ReflectionUtils.findField(enhancedConfigInstance.getClass(), BEAN_FACTORY_FIELD);
			Assert.state(field != null, "Unable to find generated bean factory field");
			Object beanFactory = ReflectionUtils.getField(field, enhancedConfigInstance);
			Assert.state(beanFactory != null, "BeanFactory has not been injected into @Configuration class");
			Assert.state(beanFactory instanceof ConfigurableBeanFactory,
					"Injected BeanFactory is not a ConfigurableBeanFactory");
			return (ConfigurableBeanFactory) beanFactory;
		}

		
Check the BeanFactory to see whether the bean named beanName already
exists. Accounts for the fact that the requested bean may be "in creation", i.e.:
we're in the middle of servicing the initial request for this bean. From an enhanced
factory method's perspective, this means that the bean does not actually yet exist,
and that it is now our job to create it for the first time by executing the logic
in the corresponding factory method.

Said another way, this check repurposes ConfigurableBeanFactory.isCurrentlyInCreation(String) to determine whether the container is calling this method or the user is calling this method. 
Params:
  • beanName – name of bean to check for
Returns:whether beanName already exists in the factory
/**
		 * Check the BeanFactory to see whether the bean named <var>beanName</var> already
		 * exists. Accounts for the fact that the requested bean may be "in creation", i.e.:
		 * we're in the middle of servicing the initial request for this bean. From an enhanced
		 * factory method's perspective, this means that the bean does not actually yet exist,
		 * and that it is now our job to create it for the first time by executing the logic
		 * in the corresponding factory method.
		 * <p>Said another way, this check repurposes
		 * {@link ConfigurableBeanFactory#isCurrentlyInCreation(String)} to determine whether
		 * the container is calling this method or the user is calling this method.
		 * @param beanName name of bean to check for
		 * @return whether <var>beanName</var> already exists in the factory
		 */
		private boolean factoryContainsBean(ConfigurableBeanFactory beanFactory, String beanName) {
			return (beanFactory.containsBean(beanName) && !beanFactory.isCurrentlyInCreation(beanName));
		}

		
Check whether the given method corresponds to the container's currently invoked
factory method. Compares method name and parameter types only in order to work
around a potential problem with covariant return types (currently only known
to happen on Groovy classes).

/**
		 * Check whether the given method corresponds to the container's currently invoked
		 * factory method. Compares method name and parameter types only in order to work
		 * around a potential problem with covariant return types (currently only known
		 * to happen on Groovy classes).
		 */
		private boolean isCurrentlyInvokedFactoryMethod(Method method) {
			Method currentlyInvoked = SimpleInstantiationStrategy.getCurrentlyInvokedFactoryMethod();
			return (currentlyInvoked != null && method.getName().equals(currentlyInvoked.getName()) &&
					Arrays.equals(method.getParameterTypes(), currentlyInvoked.getParameterTypes()));
		}

		
Create a subclass proxy that intercepts calls to getObject(), delegating to the current BeanFactory
instead of creating a new instance. These proxies are created only when calling a FactoryBean from
within a Bean method, allowing for proper scoping semantics even when working against the FactoryBean
instance directly. If a FactoryBean instance is fetched through the container via &-dereferencing,
it will not be proxied. This too is aligned with the way XML configuration works.

/**
		 * Create a subclass proxy that intercepts calls to getObject(), delegating to the current BeanFactory
		 * instead of creating a new instance. These proxies are created only when calling a FactoryBean from
		 * within a Bean method, allowing for proper scoping semantics even when working against the FactoryBean
		 * instance directly. If a FactoryBean instance is fetched through the container via &-dereferencing,
		 * it will not be proxied. This too is aligned with the way XML configuration works.
		 */
		private Object enhanceFactoryBean(final Object factoryBean, Class<?> exposedType,
				final ConfigurableBeanFactory beanFactory, final String beanName) {

			try {
				Class<?> clazz = factoryBean.getClass();
				boolean finalClass = Modifier.isFinal(clazz.getModifiers());
				boolean finalMethod = Modifier.isFinal(clazz.getMethod("getObject").getModifiers());
				if (finalClass || finalMethod) {
					if (exposedType.isInterface()) {
						if (logger.isTraceEnabled()) {
							logger.trace("Creating interface proxy for FactoryBean '" + beanName + "' of type [" +
									clazz.getName() + "] for use within another @Bean method because its " +
									(finalClass ? "implementation class" : "getObject() method") +
									" is final: Otherwise a getObject() call would not be routed to the factory.");
						}
						return createInterfaceProxyForFactoryBean(factoryBean, exposedType, beanFactory, beanName);
					}
					else {
						if (logger.isDebugEnabled()) {
							logger.debug("Unable to proxy FactoryBean '" + beanName + "' of type [" +
									clazz.getName() + "] for use within another @Bean method because its " +
									(finalClass ? "implementation class" : "getObject() method") +
									" is final: A getObject() call will NOT be routed to the factory. " +
									"Consider declaring the return type as a FactoryBean interface.");
						}
						return factoryBean;
					}
				}
			}
			catch (NoSuchMethodException ex) {
				// No getObject() method -> shouldn't happen, but as long as nobody is trying to call it...
			}

			return createCglibProxyForFactoryBean(factoryBean, beanFactory, beanName);
		}

		private Object createInterfaceProxyForFactoryBean(final Object factoryBean, Class<?> interfaceType,
				final ConfigurableBeanFactory beanFactory, final String beanName) {

			return Proxy.newProxyInstance(
					factoryBean.getClass().getClassLoader(), new Class<?>[] {interfaceType},
					(proxy, method, args) -> {
						if (method.getName().equals("getObject") && args == null) {
							return beanFactory.getBean(beanName);
						}
						return ReflectionUtils.invokeMethod(method, factoryBean, args);
					});
		}

		private Object createCglibProxyForFactoryBean(final Object factoryBean,
				final ConfigurableBeanFactory beanFactory, final String beanName) {

			Enhancer enhancer = new Enhancer();
			enhancer.setSuperclass(factoryBean.getClass());
			enhancer.setNamingPolicy(SpringNamingPolicy.INSTANCE);
			enhancer.setCallbackType(MethodInterceptor.class);

			// Ideally create enhanced FactoryBean proxy without constructor side effects,
			// analogous to AOP proxy creation in ObjenesisCglibAopProxy...
			Class<?> fbClass = enhancer.createClass();
			Object fbProxy = null;

			if (objenesis.isWorthTrying()) {
				try {
					fbProxy = objenesis.newInstance(fbClass, enhancer.getUseCache());
				}
				catch (ObjenesisException ex) {
					logger.debug("Unable to instantiate enhanced FactoryBean using Objenesis, " +
							"falling back to regular construction", ex);
				}
			}

			if (fbProxy == null) {
				try {
					fbProxy = ReflectionUtils.accessibleConstructor(fbClass).newInstance();
				}
				catch (Throwable ex) {
					throw new IllegalStateException("Unable to instantiate enhanced FactoryBean using Objenesis, " +
							"and regular FactoryBean instantiation via default constructor fails as well", ex);
				}
			}

			((Factory) fbProxy).setCallback(0, (MethodInterceptor) (obj, method, args, proxy) -> {
				if (method.getName().equals("getObject") && args.length == 0) {
					return beanFactory.getBean(beanName);
				}
				return proxy.invoke(factoryBean, args);
			});

			return fbProxy;
		}
	}

}