ASM ClassWriter uses application ClassLoader for its getCommonSuperClass check

Issue: SPR-13695

spring-beans/src/main/java/org/springframework/beans/factory/support/CglibSubclassingInstantiationStrategy.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 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.
@@ -25,6 +25,9 @@ import org.apache.commons.logging.LogFactory;
 import org.springframework.beans.BeanInstantiationException;
 import org.springframework.beans.BeanUtils;
 import org.springframework.beans.factory.BeanFactory;
+import org.springframework.beans.factory.config.ConfigurableBeanFactory;
+import org.springframework.cglib.core.ClassGenerator;
+import org.springframework.cglib.core.DefaultGeneratorStrategy;
 import org.springframework.cglib.core.SpringNamingPolicy;
 import org.springframework.cglib.proxy.Callback;
 import org.springframework.cglib.proxy.CallbackFilter;
@@ -141,6 +144,10 @@ public class CglibSubclassingInstantiationStrategy extends SimpleInstantiationSt
 			Enhancer enhancer = new Enhancer();
 			enhancer.setSuperclass(beanDefinition.getBeanClass());
 			enhancer.setNamingPolicy(SpringNamingPolicy.INSTANCE);
+			if (this.owner instanceof ConfigurableBeanFactory) {
+				ClassLoader cl = ((ConfigurableBeanFactory) this.owner).getBeanClassLoader();
+				enhancer.setStrategy(new ClassLoaderAwareGeneratorStrategy(cl));
+			}
 			enhancer.setCallbackFilter(new MethodOverrideCallbackFilter(beanDefinition));
 			enhancer.setCallbackTypes(CALLBACK_TYPES);
 			return enhancer.createClass();
@@ -178,6 +185,52 @@ public class CglibSubclassingInstantiationStrategy extends SimpleInstantiationSt
 	}
 
 
+	/**
+	 * CGLIB GeneratorStrategy variant which 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 ClassLoaderAwareGeneratorStrategy extends DefaultGeneratorStrategy {
+
+		private final ClassLoader classLoader;
+
+		public ClassLoaderAwareGeneratorStrategy(ClassLoader classLoader) {
+			this.classLoader = classLoader;
+		}
+
+		@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);
+				}
+			}
+		}
+	}
+
+
 	/**
 	 * CGLIB callback for filtering method interception behavior.
 	 */