DATACMNS-532 - Added support for default methods on repository interfaces.

DefaultRepositoryInformation now excludes default methods from the query methods it detects. RepositoryFactorySupport adds a special MethodInterceptor to the proxy which handles the invocation of default methods.

Related tickets: DATACMNS-535.

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

@@ -35,6 +35,7 @@ import org.springframework.data.repository.Repository;
 import org.springframework.data.repository.core.CrudMethods;
 import org.springframework.data.repository.core.RepositoryInformation;
 import org.springframework.data.repository.core.RepositoryMetadata;
+import org.springframework.data.util.ReflectionUtils;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 
@@ -172,7 +173,7 @@ class DefaultRepositoryInformation implements RepositoryInformation {
 	 * @return
 	 */
 	private boolean isQueryMethodCandidate(Method method) {
-		return !method.isBridge() //
+		return !method.isBridge() && !ReflectionUtils.isDefaultMethod(method) //
 				&& (isQueryAnnotationPresentOn(method) || !isCustomMethod(method) && !isBaseClassMethod(method));
 	}
 

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

@@ -18,6 +18,8 @@ package org.springframework.data.repository.core.support;
 import static org.springframework.util.ReflectionUtils.*;
 
 import java.io.Serializable;
+import java.lang.invoke.MethodHandles;
+import java.lang.reflect.Constructor;
 import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.HashMap;
@@ -27,6 +29,7 @@ import java.util.concurrent.ConcurrentHashMap;
 
 import org.aopalliance.intercept.MethodInterceptor;
 import org.aopalliance.intercept.MethodInvocation;
+import org.springframework.aop.ProxyMethodInvocation;
 import org.springframework.aop.framework.ProxyFactory;
 import org.springframework.beans.factory.BeanClassLoaderAware;
 import org.springframework.core.GenericTypeResolver;
@@ -59,6 +62,8 @@ import org.springframework.util.ObjectUtils;
 public abstract class RepositoryFactorySupport implements BeanClassLoaderAware {
 
 	private static final TypeDescriptor WRAPPER_TYPE = TypeDescriptor.valueOf(NullableWrapper.class);
+	private static final boolean IS_JAVA_8 = org.springframework.util.ClassUtils.isPresent("java.util.Optional",
+			RepositoryFactorySupport.class.getClassLoader());
 
 	private final Map<RepositoryInformationCacheKey, RepositoryInformation> REPOSITORY_INFORMATION_CACHE = new HashMap<RepositoryInformationCacheKey, RepositoryInformation>();
 
@@ -166,6 +171,10 @@ public abstract class RepositoryFactorySupport implements BeanClassLoaderAware {
 			processor.postProcess(result, information);
 		}
 
+		if (IS_JAVA_8) {
+			result.addAdvice(new DefaultMethodInvokingMethodInterceptor());
+		}
+
 		result.addAdvice(new QueryExecutorMethodInterceptor(information, customImplementation, target));
 
 		return (T) result.getProxy(classLoader);
@@ -437,6 +446,53 @@ public abstract class RepositoryFactorySupport implements BeanClassLoaderAware {
 		}
 	}
 
+	/**
+	 * Method interceptor to invoke default methods on the repository proxy.
+	 *
+	 * @author Oliver Gierke
+	 */
+	private static class DefaultMethodInvokingMethodInterceptor implements MethodInterceptor {
+
+		private final Constructor<MethodHandles.Lookup> constructor;
+
+		/**
+		 * Creates a new {@link DefaultMethodInvokingMethodInterceptor}.
+		 */
+		public DefaultMethodInvokingMethodInterceptor() {
+
+			try {
+				this.constructor = MethodHandles.Lookup.class.getDeclaredConstructor(Class.class, int.class);
+
+				if (!constructor.isAccessible()) {
+					constructor.setAccessible(true);
+				}
+			} catch (Exception o_O) {
+				throw new IllegalStateException(o_O);
+			}
+		}
+
+		/* 
+		 * (non-Javadoc)
+		 * @see org.aopalliance.intercept.MethodInterceptor#invoke(org.aopalliance.intercept.MethodInvocation)
+		 */
+		@Override
+		public Object invoke(MethodInvocation invocation) throws Throwable {
+
+			Method method = invocation.getMethod();
+
+			if (!org.springframework.data.util.ReflectionUtils.isDefaultMethod(method)) {
+				return invocation.proceed();
+			}
+
+			Object[] arguments = invocation.getArguments();
+			Class<?> declaringClass = method.getDeclaringClass();
+			Object proxy = ((ProxyMethodInvocation) invocation).getProxy();
+
+			return constructor.newInstance(declaringClass, MethodHandles.Lookup.PRIVATE)
+					.unreflectSpecial(method, declaringClass).bindTo(proxy).invokeWithArguments(arguments);
+		}
+	}
+
 	/**
 	 * {@link QueryCreationListener} collecting the {@link QueryMethod}s created for all query methods of the repository
 	 * interface.

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

@@ -17,6 +17,8 @@ package org.springframework.data.util;
 
 import java.lang.annotation.Annotation;
 import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
 
 import org.springframework.beans.BeanUtils;
 import org.springframework.core.annotation.AnnotationUtils;
@@ -51,6 +53,18 @@ public class ReflectionUtils {
 		}
 	}
 
+	/**
+	 * Back-port of Java 8's {@code isDefault()} method on {@link Method}.
+	 * 
+	 * @param method must not be {@literal null}.
+	 * @return
+	 */
+	public static boolean isDefaultMethod(Method method) {
+
+		return ((method.getModifiers() & (Modifier.ABSTRACT | Modifier.PUBLIC | Modifier.STATIC)) == Modifier.PUBLIC)
+				&& method.getDeclaringClass().isInterface();
+	}
+
 	/**
 	 * A {@link FieldFilter} that has a description.
 	 *