AnnotationAwareOrderComparator uses DecoratingProxy interface for target class introspection

Issue: SPR-13884

spring-core/src/main/java/org/springframework/core/DecoratingProxy.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2002-2016 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.core;
+
+/**
+ * Interface to be implemented by decorating proxies, in particular Spring AOP
+ * proxies but potentially also custom proxies with decorator semantics.
+ *
+ * <p>Note that this interface should just be implemented if the decorated class
+ * is not within the hierarchy of the proxy class to begin with. In particular,
+ * a "target-class" proxy such as a Spring AOP CGLIB proxy should not implement
+ * it since any lookup on the target class can simply be performed on the proxy
+ * class there anyway.
+ *
+ * <p>Defined in the core module in order to allow
+ * #{@link org.springframework.core.annotation.AnnotationAwareOrderComparator}
+ * (and potential other candidates without spring-aop dependencies) to use it
+ * for introspection purposes, in particular annotation lookups.
+ *
+ * @author Juergen Hoeller
+ * @since 4.3
+ */
+public interface DecoratingProxy {
+
+	/**
+	 * Return the (ultimate) decorated class behind this proxy.
+	 * <p>In case of an AOP proxy, this will be the ultimate target class,
+	 * not just the immediate target (in case of multiple nested proxies).
+	 * @return the decorated class (never {@code null})
+	 */
+	Class<?> getDecoratedClass();
+
+}

spring-core/src/main/java/org/springframework/core/annotation/AnnotationAwareOrderComparator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -23,6 +23,7 @@ import java.util.Collections;
 import java.util.List;
 
 import org.springframework.core.OrderComparator;
+import org.springframework.core.DecoratingProxy;
 
 /**
  * {@code AnnotationAwareOrderComparator} is an extension of
@@ -81,10 +82,13 @@ public class AnnotationAwareOrderComparator extends OrderComparator {
 			}
 		}
 		else if (obj != null) {
-			return OrderUtils.getOrder(obj.getClass());
+			order = OrderUtils.getOrder(obj.getClass());
+			if (order == null && obj instanceof DecoratingProxy) {
+				order = OrderUtils.getOrder(((DecoratingProxy) obj).getDecoratedClass());
+			}
 		}
 
-		return null;
+		return order;
 	}
 
 	/**
@@ -94,13 +98,17 @@ public class AnnotationAwareOrderComparator extends OrderComparator {
 	 * multiple matches but only one object to be returned.
 	 */
 	public Integer getPriority(Object obj) {
+		Integer priority = null;
 		if (obj instanceof Class) {
-			return OrderUtils.getPriority((Class<?>) obj);
+			priority = OrderUtils.getPriority((Class<?>) obj);
 		}
 		else if (obj != null) {
-			return OrderUtils.getPriority(obj.getClass());
+			priority = OrderUtils.getPriority(obj.getClass());
+			if (priority == null && obj instanceof DecoratingProxy) {
+				priority = OrderUtils.getOrder(((DecoratingProxy) obj).getDecoratedClass());
+			}
 		}
-		return null;
+		return priority;
 	}