Auto-adapt reflective arguments in case of vararg array type mismatch

Issue: SPR-13328

Author: jhoeller

spring-aop/src/main/java/org/springframework/aop/ProxyMethodInvocation.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 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.
@@ -57,14 +57,14 @@ public interface ProxyMethodInvocation extends MethodInvocation {
 	 * @return an invocable clone of this invocation.
 	 * {@code proceed()} can be called once per clone.
 	 */
-	MethodInvocation invocableClone(Object[] arguments);
+	MethodInvocation invocableClone(Object... arguments);
 
 	/**
 	 * Set the arguments to be used on subsequent invocations in the any advice
 	 * in this chain.
 	 * @param arguments the argument array
 	 */
-	void setArguments(Object[] arguments);
+	void setArguments(Object... arguments);
 
 	/**
 	 * Add the specified user attribute with the given value to this invocation.

spring-aop/src/main/java/org/springframework/aop/framework/AopProxyUtils.java

@@ -16,6 +16,8 @@
 
 package org.springframework.aop.framework;
 
+import java.lang.reflect.Array;
+import java.lang.reflect.Method;
 import java.lang.reflect.Proxy;
 import java.util.Arrays;
 
@@ -25,6 +27,7 @@
 import org.springframework.aop.support.AopUtils;
 import org.springframework.aop.target.SingletonTargetSource;
 import org.springframework.util.Assert;
+import org.springframework.util.ObjectUtils;
 
 /**
  * Utility methods for AOP proxy factories.
@@ -161,4 +164,38 @@ public static boolean equalsAdvisors(AdvisedSupport a, AdvisedSupport b) {
 		return Arrays.equals(a.getAdvisors(), b.getAdvisors());
 	}
 
+
+	/**
+	 * Adapt the given arguments to the target signature in the given method,
+	 * if necessary: in particular, if a given vararg argument array does not
+	 * match the array type of the declared vararg parameter in the method.
+	 * @param method the target method
+	 * @param arguments the given arguments
+	 * @return a cloned argument array, or the original if no adaptation is needed
+	 * @since 4.2.3
+	 */
+	static Object[] adaptArgumentsIfNecessary(Method method, Object... arguments) {
+		if (method.isVarArgs() && !ObjectUtils.isEmpty(arguments)) {
+			Class<?>[] paramTypes = method.getParameterTypes();
+			if (paramTypes.length == arguments.length) {
+				int varargIndex = paramTypes.length - 1;
+				Class<?> varargType = paramTypes[varargIndex];
+				if (varargType.isArray()) {
+					Object varargArray = arguments[varargIndex];
+					if (varargArray instanceof Object[] && !varargType.isInstance(varargArray)) {
+						Object[] newArguments = new Object[arguments.length];
+						System.arraycopy(arguments, 0, newArguments, 0, varargIndex);
+						Class<?> targetElementType = varargType.getComponentType();
+						int varargLength = Array.getLength(varargArray);
+						Object newVarargArray = Array.newInstance(targetElementType, varargLength);
+						System.arraycopy(varargArray, 0, newVarargArray, 0, varargLength);
+						newArguments[varargIndex] = newVarargArray;
+						return newArguments;
+					}
+				}
+			}
+		}
+		return arguments;
+	}
+
 }

spring-aop/src/main/java/org/springframework/aop/framework/JdkDynamicAopProxy.java

@@ -198,7 +198,8 @@ public Object invoke(Object proxy, Method method, Object[] args) throws Throwabl
 				// We can skip creating a MethodInvocation: just invoke the target directly
 				// Note that the final invoker must be an InvokerInterceptor so we know it does
 				// nothing but a reflective operation on the target, and no hot swapping or fancy proxying.
-				retVal = AopUtils.invokeJoinpointUsingReflection(target, method, args);
+				Object[] argsToUse = AopProxyUtils.adaptArgumentsIfNecessary(method, args);
+				retVal = AopUtils.invokeJoinpointUsingReflection(target, method, argsToUse);
 			}
 			else {
 				// We need to create a method invocation...

spring-aop/src/main/java/org/springframework/aop/framework/ReflectiveMethodInvocation.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 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.
@@ -109,7 +109,7 @@ protected ReflectiveMethodInvocation(
 		this.target = target;
 		this.targetClass = targetClass;
 		this.method = BridgeMethodResolver.findBridgedMethod(method);
-		this.arguments = arguments;
+		this.arguments = AopProxyUtils.adaptArgumentsIfNecessary(method, arguments);
 		this.interceptorsAndDynamicMethodMatchers = interceptorsAndDynamicMethodMatchers;
 	}
 
@@ -145,7 +145,7 @@ public final Object[] getArguments() {
 	}
 
 	@Override
-	public void setArguments(Object[] arguments) {
+	public void setArguments(Object... arguments) {
 		this.arguments = arguments;
 	}
 
@@ -219,7 +219,7 @@ public MethodInvocation invocableClone() {
 	 * @see java.lang.Object#clone()
 	 */
 	@Override
-	public MethodInvocation invocableClone(Object[] arguments) {
+	public MethodInvocation invocableClone(Object... arguments) {
 		// Force initialization of the user attributes Map,
 		// for having a shared Map reference in the clone.
 		if (this.userAttributes == null) {