Create enhanced FactoryBean instance before applying method interceptor (preferably via Objenesis)

Also removes "throws Exception" declaration from ThreadPoolExecutorFactoryBean's getObject method.

Issue: SPR-13095

spring-context/src/main/java/org/springframework/context/annotation/ConfigurationClassEnhancer.java

@@ -39,12 +39,17 @@ 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.core.annotation.AnnotationUtils;
+import org.springframework.objenesis.Objenesis;
+import org.springframework.objenesis.ObjenesisException;
+import org.springframework.objenesis.ObjenesisStd;
+import org.springframework.objenesis.SpringObjenesis;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ObjectUtils;
@@ -82,6 +87,10 @@ class ConfigurationClassEnhancer {
 
 	private static final Log logger = LogFactory.getLog(ConfigurationClassEnhancer.class);
 
+	private static final Objenesis cachedObjenesis = new SpringObjenesis();
+
+	private static final Objenesis nonCachedObjenesis = new ObjenesisStd(false);
+
 
 	/**
 	 * Loads the specified class and generates a CGLIB subclass of it equipped with
@@ -388,9 +397,25 @@ class ConfigurationClassEnhancer {
 
 			Enhancer enhancer = new Enhancer();
 			enhancer.setSuperclass(factoryBean.getClass());
-			enhancer.setUseFactory(false);
 			enhancer.setNamingPolicy(SpringNamingPolicy.INSTANCE);
-			enhancer.setCallback(new MethodInterceptor() {
+			enhancer.setCallbackType(MethodInterceptor.class);
+
+			// Ideally create enhanced FactoryBean proxy without constructor side effects,
+			// analogous to AOP proxy creation in ObjenesisCglibAopProxy...
+			Class<?> fbClass = enhancer.createClass();
+			Objenesis objenesis = (enhancer.getUseCache() ? cachedObjenesis : nonCachedObjenesis);
+			Factory factory;
+			try {
+				factory = (Factory) objenesis.newInstance(fbClass);
+			}
+			catch (ObjenesisException ex) {
+				// Fallback to regular proxy construction on unsupported JVMs
+				logger.debug("Unable to instantiate enhanced FactoryBean using Objenesis, " +
+						"falling back to regular construction", ex);
+				factory = (Factory) fbClass.newInstance();
+			}
+
+			factory.setCallback(0, new MethodInterceptor() {
 				@Override
 				public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy) throws Throwable {
 					if (method.getName().equals("getObject") && args.length == 0) {
@@ -399,7 +424,8 @@ class ConfigurationClassEnhancer {
 					return proxy.invoke(factoryBean, args);
 				}
 			});
-			return enhancer.create();
+
+			return factory;
 		}
 
 		private ConfigurableBeanFactory getBeanFactory(Object enhancedConfigInstance) {

spring-context/src/main/java/org/springframework/scheduling/concurrent/ThreadPoolExecutorFactoryBean.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2015 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.
@@ -187,7 +187,7 @@ public class ThreadPoolExecutorFactoryBean extends ExecutorConfigurationSupport
 
 
 	@Override
-	public ExecutorService getObject() throws Exception {
+	public ExecutorService getObject() {
 		return this.exposedExecutor;
 	}