Allow @CachePut 'key' SpEL to refer to #result

Allow the @CachePut 'key' SpEL to refer to the result of the method call
via a '#result' variable.

This change is particularly useful when working with JPA entities that
have generated @Id values since the ID will often not be available
until the entity has been saved.

Issue: SPR-10664

spring-aspects/src/test/java/org/springframework/cache/config/AnnotatedClassCacheableService.java

@@ -163,4 +163,11 @@ public class AnnotatedClassCacheableService implements CacheableService<Object>
 	public Object multiUpdate(Object arg1) {
 		return arg1;
 	}
+
+	@Override
+	@CachePut(value="primary", key="#result.id")
+	public TestEntity putRefersToResult(TestEntity arg1) {
+		arg1.setId(Long.MIN_VALUE);
+		return arg1;
+	}
 }

spring-aspects/src/test/java/org/springframework/cache/config/CacheableService.java

@@ -70,4 +70,6 @@ public interface CacheableService<T> {
 	T multiConditionalCacheAndEvict(Object arg1);
 
 	T multiUpdate(Object arg1);
+
+	TestEntity putRefersToResult(TestEntity arg1);
 }

spring-aspects/src/test/java/org/springframework/cache/config/DefaultCacheableService.java

@@ -171,4 +171,11 @@ public class DefaultCacheableService implements CacheableService<Long> {
 	public Long multiUpdate(Object arg1) {
 		return Long.valueOf(arg1.toString());
 	}
+
+	@Override
+	@CachePut(value="primary", key="#result.id")
+	public TestEntity putRefersToResult(TestEntity arg1) {
+		arg1.setId(Long.MIN_VALUE);
+		return arg1;
+	}
 }

spring-aspects/src/test/java/org/springframework/cache/config/TestEntity.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2002-2013 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.cache.config;
+
+import org.springframework.util.ObjectUtils;
+
+/**
+ * Simple test entity for use with caching tests.
+ *
+ * @author Michael Pl<50>d
+ */
+public class TestEntity {
+
+	private Long id;
+
+	public Long getId() {
+		return this.id;
+	}
+
+	public void setId(Long id) {
+		this.id = id;
+	}
+
+	@Override
+	public int hashCode() {
+		return ObjectUtils.nullSafeHashCode(this.id);
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (obj == this) {
+			return true;
+		}
+		if (obj == null) {
+			return false;
+		}
+		if (obj instanceof TestEntity) {
+			return ObjectUtils.nullSafeEquals(this.id, ((TestEntity) obj).id);
+		}
+		return false;
+	}
+}