DATACMNS-1324 - Introduced extensible proxy detection infrastructure.

Introduced ProxyUtils.getUserClass(…) that by default is basically a facade for Spring's ClassUtils.getUserClass(…) but allows the registration of ProxyDetector implementations via Spring's SpringFactoriesLoader mechanism.

Moved all existing usages of ClassUtils.getUserClass(…) to ProxyUtils.

src/main/java/org/springframework/data/domain/Example.java

@@ -15,7 +15,7 @@
  */
 package org.springframework.data.domain;
 
-import org.springframework.util.ClassUtils;
+import org.springframework.data.util.ProxyUtils;
 
 /**
  * Support for query by example (QBE). An {@link Example} takes a {@code probe} to define the example. Matching options
@@ -69,10 +69,10 @@ public interface Example<T> {
 	 * CGLIB-generated subclass.
 	 *
 	 * @return
-	 * @see ClassUtils#getUserClass(Class)
+	 * @see ProxyUtils#getUserClass(Class)
 	 */
 	@SuppressWarnings("unchecked")
 	default Class<T> getProbeType() {
-		return (Class<T>) ClassUtils.getUserClass(getProbe().getClass());
+		return (Class<T>) ProxyUtils.getUserClass(getProbe().getClass());
 	}
 }

src/main/java/org/springframework/data/repository/core/support/TransactionalRepositoryProxyPostProcessor.java

@@ -33,6 +33,7 @@ import org.springframework.beans.factory.ListableBeanFactory;
 import org.springframework.core.BridgeMethodResolver;
 import org.springframework.dao.support.PersistenceExceptionTranslationInterceptor;
 import org.springframework.data.repository.core.RepositoryInformation;
+import org.springframework.data.util.ProxyUtils;
 import org.springframework.transaction.annotation.Ejb3TransactionAnnotationParser;
 import org.springframework.transaction.annotation.JtaTransactionAnnotationParser;
 import org.springframework.transaction.annotation.SpringTransactionAnnotationParser;
@@ -386,7 +387,7 @@ class TransactionalRepositoryProxyPostProcessor implements RepositoryProxyPostPr
 			}
 
 			// Ignore CGLIB subclasses - introspect the actual user class.
-			Class<?> userClass = ClassUtils.getUserClass(targetClass);
+			Class<?> userClass = ProxyUtils.getUserClass(targetClass);
 			// The method may be on an interface, but we need attributes from the target class.
 			// If the target class is null, the method will be unchanged.
 			Method specificMethod = ClassUtils.getMostSpecificMethod(method, userClass);

src/main/java/org/springframework/data/repository/support/Repositories.java

@@ -33,6 +33,7 @@ import org.springframework.data.repository.core.EntityInformation;
 import org.springframework.data.repository.core.RepositoryInformation;
 import org.springframework.data.repository.core.support.RepositoryFactoryInformation;
 import org.springframework.data.repository.query.QueryMethod;
+import org.springframework.data.util.ProxyUtils;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 
@@ -122,7 +123,7 @@ public class Repositories implements Iterable<Class<?>> {
 
 		Assert.notNull(domainClass, DOMAIN_TYPE_MUST_NOT_BE_NULL);
 
-		Class<?> userClass = ClassUtils.getUserClass(domainClass);
+		Class<?> userClass = ProxyUtils.getUserClass(domainClass);
 
 		return repositoryFactoryInfos.containsKey(userClass);
 	}
@@ -137,7 +138,7 @@ public class Repositories implements Iterable<Class<?>> {
 
 		Assert.notNull(domainClass, DOMAIN_TYPE_MUST_NOT_BE_NULL);
 
-		Class<?> userClass = ClassUtils.getUserClass(domainClass);
+		Class<?> userClass = ProxyUtils.getUserClass(domainClass);
 		Optional<String> repositoryBeanName = Optional.ofNullable(repositoryBeanNames.get(userClass));
 
 		return beanFactory.flatMap(it -> repositoryBeanName.map(it::getBean));
@@ -145,7 +146,7 @@ public class Repositories implements Iterable<Class<?>> {
 
 	/**
 	 * Returns the {@link RepositoryFactoryInformation} for the given domain class. The given <code>code</code> is
-	 * converted to the actual user class if necessary, @see ClassUtils#getUserClass.
+	 * converted to the actual user class if necessary, @see ProxyUtils#getUserClass.
 	 *
 	 * @param domainClass must not be {@literal null}.
 	 * @return the {@link RepositoryFactoryInformation} for the given domain class or {@literal null} if no repository
@@ -155,7 +156,7 @@ public class Repositories implements Iterable<Class<?>> {
 
 		Assert.notNull(domainClass, DOMAIN_TYPE_MUST_NOT_BE_NULL);
 
-		Class<?> userType = ClassUtils.getUserClass(domainClass);
+		Class<?> userType = ProxyUtils.getUserClass(domainClass);
 		RepositoryFactoryInformation<Object, Object> repositoryInfo = repositoryFactoryInfos.get(userType);
 
 		if (repositoryInfo != null) {

src/main/java/org/springframework/data/repository/util/ReactiveWrappers.java

@@ -31,6 +31,7 @@ import java.util.stream.Collectors;
 
 import org.reactivestreams.Publisher;
 import org.springframework.core.ReactiveTypeDescriptor;
+import org.springframework.data.util.ProxyUtils;
 import org.springframework.data.util.ReflectionUtils;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
@@ -154,7 +155,7 @@ public class ReactiveWrappers {
 	 * @return {@literal true} if the {@code type} is a supported reactive wrapper type.
 	 */
 	public static boolean supports(Class<?> type) {
-		return isWrapper(ClassUtils.getUserClass(type));
+		return isWrapper(ProxyUtils.getUserClass(type));
 	}
 
 	/**

src/main/java/org/springframework/data/util/ClassTypeInformation.java

@@ -89,7 +89,7 @@ public class ClassTypeInformation<S> extends TypeDiscoverer<S> {
 	 * @param type
 	 */
 	ClassTypeInformation(Class<S> type) {
-		super(ClassUtils.getUserClass(type), getTypeVariableMap(type));
+		super(ProxyUtils.getUserClass(type), getTypeVariableMap(type));
 		this.type = type;
 	}
 

src/main/java/org/springframework/data/util/ProxyUtils.java

@@ -0,0 +1,96 @@
+/*
+ * Copyright 2018 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.data.util;
+
+import lombok.experimental.UtilityClass;
+
+import java.util.List;
+import java.util.Map;
+
+import org.springframework.core.io.support.SpringFactoriesLoader;
+import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
+import org.springframework.util.ConcurrentReferenceHashMap;
+
+/**
+ * Proxy type detection utilities, extensible via {@link ProxyDetector} registered via Spring factories.
+ * 
+ * @author Oliver Gierke
+ * @soundtrack Victor Wooten - Cruising Altitude (Trypnotix)
+ */
+@UtilityClass
+public class ProxyUtils {
+
+	private static Map<Class<?>, Class<?>> USER_TYPES = new ConcurrentReferenceHashMap<>();
+
+	private static final List<ProxyDetector> DETECTORS = SpringFactoriesLoader.loadFactories(ProxyDetector.class,
+			ProxyUtils.class.getClassLoader());
+
+	static {
+		DETECTORS.add(ClassUtils::getUserClass);
+	}
+
+	/**
+	 * Returns the user class for the given type.
+	 * 
+	 * @param type must not be {@literal null}.
+	 * @return
+	 */
+	public static Class<?> getUserClass(Class<?> type) {
+
+		Assert.notNull(type, "Type must not be null!");
+
+		return USER_TYPES.computeIfAbsent(type, it -> {
+
+			Class<?> result = it;
+
+			for (ProxyDetector proxyDetector : DETECTORS) {
+				result = proxyDetector.getUserType(result);
+			}
+
+			return result;
+		});
+	}
+
+	/**
+	 * Returns the user class for the given source object.
+	 * 
+	 * @param source must not be {@literal null}.
+	 * @return
+	 */
+	public static Class<?> getUserClass(Object source) {
+
+		Assert.notNull(source, "Source object must not be null!");
+
+		return getUserClass(source.getClass());
+	}
+
+	/**
+	 * SPI to extend Spring's default proxy detection capabilities.
+	 *
+	 * @author Oliver Gierke
+	 */
+	public interface ProxyDetector {
+
+		/**
+		 * Returns the user class for the given type.
+		 * 
+		 * @param type will never be {@literal null}.
+		 * @return
+		 */
+		Class<?> getUserType(Class<?> type);
+	}
+}