Extract ValueExtractor functional interface

See gh-24375

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

@@ -28,7 +28,6 @@ import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
-import java.util.function.BiFunction;
 
 import org.springframework.core.annotation.AnnotationTypeMapping.MirrorSets.MirrorSet;
 import org.springframework.lang.Nullable;
@@ -465,8 +464,7 @@ final class AnnotationTypeMapping {
 	 * nested annotations
 	 * @return {@code true} if the value is equivalent to the default value
 	 */
-	boolean isEquivalentToDefaultValue(int attributeIndex, Object value,
-			BiFunction<Method, Object, Object> valueExtractor) {
+	boolean isEquivalentToDefaultValue(int attributeIndex, Object value, ValueExtractor valueExtractor) {
 
 		Method attribute = this.attributes.get(attributeIndex);
 		return isEquivalentToDefaultValue(attribute, value, valueExtractor);
@@ -488,13 +486,13 @@ final class AnnotationTypeMapping {
 	}
 
 	private static boolean isEquivalentToDefaultValue(Method attribute, Object value,
-			BiFunction<Method, Object, Object> valueExtractor) {
+			ValueExtractor valueExtractor) {
 
 		return areEquivalent(attribute.getDefaultValue(), value, valueExtractor);
 	}
 
 	private static boolean areEquivalent(@Nullable Object value, @Nullable Object extractedValue,
-			BiFunction<Method, Object, Object> valueExtractor) {
+			ValueExtractor valueExtractor) {
 
 		if (ObjectUtils.nullSafeEquals(value, extractedValue)) {
 			return true;
@@ -528,7 +526,7 @@ final class AnnotationTypeMapping {
 	}
 
 	private static boolean areEquivalent(Annotation annotation, @Nullable Object extractedValue,
-			BiFunction<Method, Object, Object> valueExtractor) {
+			ValueExtractor valueExtractor) {
 
 		AttributeMethods attributes = AttributeMethods.forAnnotationType(annotation.annotationType());
 		for (int i = 0; i < attributes.size(); i++) {
@@ -539,7 +537,7 @@ final class AnnotationTypeMapping {
 				value2 = ((TypeMappedAnnotation<?>) extractedValue).getValue(attribute.getName()).orElse(null);
 			}
 			else {
-				value2 = valueExtractor.apply(attribute, extractedValue);
+				value2 = valueExtractor.extract(attribute, extractedValue);
 			}
 			if (!areEquivalent(value1, value2, valueExtractor)) {
 				return false;
@@ -603,9 +601,7 @@ final class AnnotationTypeMapping {
 			return this.assigned[attributeIndex];
 		}
 
-		int[] resolve(@Nullable Object source, @Nullable Object annotation,
-				BiFunction<Method, Object, Object> valueExtractor) {
-
+		int[] resolve(@Nullable Object source, @Nullable Object annotation, ValueExtractor valueExtractor) {
 			int[] result = new int[attributes.size()];
 			for (int i = 0; i < result.length; i++) {
 				result[i] = i;
@@ -641,14 +637,12 @@ final class AnnotationTypeMapping {
 				}
 			}
 
-			<A> int resolve(@Nullable Object source, @Nullable A annotation,
-					BiFunction<Method, Object, Object> valueExtractor) {
-
+			<A> int resolve(@Nullable Object source, @Nullable A annotation, ValueExtractor valueExtractor) {
 				int result = -1;
 				Object lastValue = null;
 				for (int i = 0; i < this.size; i++) {
 					Method attribute = attributes.get(this.indexes[i]);
-					Object value = valueExtractor.apply(attribute, annotation);
+					Object value = valueExtractor.extract(attribute, annotation);
 					boolean isDefaultValue = (value == null ||
 							isEquivalentToDefaultValue(attribute, value, valueExtractor));
 					if (isDefaultValue || ObjectUtils.nullSafeEquals(lastValue, value)) {

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

@@ -27,7 +27,6 @@ import java.util.List;
 import java.util.Map;
 import java.util.NoSuchElementException;
 import java.util.Optional;
-import java.util.function.BiFunction;
 import java.util.function.Function;
 import java.util.function.Predicate;
 
@@ -64,6 +63,7 @@ import org.springframework.util.ReflectionUtils;
  *
  * @author Phillip Webb
  * @author Juergen Hoeller
+ * @author Sam Brannen
  * @since 5.2
  * @param <A> the annotation type
  * @see TypeMappedAnnotations
@@ -96,7 +96,7 @@ final class TypeMappedAnnotation<A extends Annotation> extends AbstractMergedAnn
 	@Nullable
 	private final Object rootAttributes;
 
-	private final BiFunction<Method, Object, Object> valueExtractor;
+	private final ValueExtractor valueExtractor;
 
 	private final int aggregateIndex;
 
@@ -114,16 +114,15 @@ final class TypeMappedAnnotation<A extends Annotation> extends AbstractMergedAnn
 
 
 	private TypeMappedAnnotation(AnnotationTypeMapping mapping, @Nullable ClassLoader classLoader,
-			@Nullable Object source, @Nullable Object rootAttributes,
-			BiFunction<Method, Object, Object> valueExtractor, int aggregateIndex) {
+			@Nullable Object source, @Nullable Object rootAttributes, ValueExtractor valueExtractor,
+			int aggregateIndex) {
 
 		this(mapping, classLoader, source, rootAttributes, valueExtractor, aggregateIndex, null);
 	}
 
 	private TypeMappedAnnotation(AnnotationTypeMapping mapping, @Nullable ClassLoader classLoader,
-			@Nullable Object source, @Nullable Object rootAttributes,
-			BiFunction<Method, Object, Object> valueExtractor, int aggregateIndex,
-			@Nullable int[] resolvedRootMirrors) {
+			@Nullable Object source, @Nullable Object rootAttributes, ValueExtractor valueExtractor,
+			int aggregateIndex, @Nullable int[] resolvedRootMirrors) {
 
 		this.mapping = mapping;
 		this.classLoader = classLoader;
@@ -140,9 +139,8 @@ final class TypeMappedAnnotation<A extends Annotation> extends AbstractMergedAnn
 	}
 
 	private TypeMappedAnnotation(AnnotationTypeMapping mapping, @Nullable ClassLoader classLoader,
-			@Nullable Object source, @Nullable Object rootAnnotation,
-			BiFunction<Method, Object, Object> valueExtractor, int aggregateIndex,
-			boolean useMergedValues, @Nullable Predicate<String> attributeFilter,
+			@Nullable Object source, @Nullable Object rootAnnotation, ValueExtractor valueExtractor,
+			int aggregateIndex, boolean useMergedValues, @Nullable Predicate<String> attributeFilter,
 			int[] resolvedRootMirrors, int[] resolvedMirrors) {
 
 		this.classLoader = classLoader;
@@ -426,7 +424,7 @@ final class TypeMappedAnnotation<A extends Annotation> extends AbstractMergedAnn
 		}
 		if (mapping.getDistance() == 0) {
 			Method attribute = mapping.getAttributes().get(attributeIndex);
-			Object result = this.valueExtractor.apply(attribute, this.rootAttributes);
+			Object result = this.valueExtractor.extract(attribute, this.rootAttributes);
 			return (result != null) ? result : attribute.getDefaultValue();
 		}
 		return getValueFromMetaAnnotation(attributeIndex, forMirrorResolution);
@@ -562,7 +560,7 @@ final class TypeMappedAnnotation<A extends Annotation> extends AbstractMergedAnn
 				mapping, null, this.source, value, getValueExtractor(value), this.aggregateIndex);
 	}
 
-	private BiFunction<Method, Object, Object> getValueExtractor(Object value) {
+	private ValueExtractor getValueExtractor(Object value) {
 		if (value instanceof Annotation) {
 			return ReflectionUtils::invokeMethod;
 		}
@@ -664,8 +662,7 @@ final class TypeMappedAnnotation<A extends Annotation> extends AbstractMergedAnn
 	@Nullable
 	private static <A extends Annotation> TypeMappedAnnotation<A> createIfPossible(
 			AnnotationTypeMapping mapping, @Nullable Object source, @Nullable Object rootAttribute,
-			BiFunction<Method, Object, Object> valueExtractor,
-			int aggregateIndex, IntrospectionFailureLogger logger) {
+			ValueExtractor valueExtractor, int aggregateIndex, IntrospectionFailureLogger logger) {
 
 		try {
 			return new TypeMappedAnnotation<>(mapping, null, source, rootAttribute,

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

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2002-2020 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
+ *
+ *      https://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.annotation;
+
+import java.lang.annotation.Annotation;
+import java.lang.reflect.Method;
+import java.util.Map;
+
+import org.springframework.lang.Nullable;
+
+/**
+ * Strategy API for extracting a value for an annotation attribute from a given
+ * source object which is typically an {@link Annotation}, {@link Map}, or
+ * {@link TypeMappedAnnotation}.
+ *
+ * @since 5.2.4
+ * @author Sam Brannen
+ */
+@FunctionalInterface
+interface ValueExtractor {
+
+	/**
+	 * Extract the annotation attribute represented by the supplied {@link Method}
+	 * from the supplied source {@link Object}.
+	 */
+	@Nullable
+	Object extract(Method attribute, @Nullable Object object);
+
+}