DATAREST-684 - ProxyProjectionFactory now exposes target instance on proxy.

Changed TargetClassAware to TargetAware and expose the actual proxy target for framework purposes.

Author: odrotbohm

src/main/java/org/springframework/data/projection/ProxyProjectionFactory.java

@@ -29,8 +29,6 @@
 import org.springframework.beans.BeanUtils;
 import org.springframework.util.Assert;
 
-import com.fasterxml.jackson.annotation.JsonIgnore;
-
 /**
  * A {@link ProjectionFactory} to create JDK proxies to back interfaces and handle method invocations on them. By
  * default accessor methods are supported. In case the delegating lookups result in an object of different type that the
@@ -64,13 +62,13 @@ public <T> T createProjection(Class<T> projectionType, Object source) {
 		ProxyFactory factory = new ProxyFactory();
 		factory.setTarget(source);
 		factory.setOpaque(true);
-		factory.setInterfaces(projectionType, TargetClassAware.class);
+		factory.setInterfaces(projectionType, TargetAware.class);
 
 		if (IS_JAVA_8) {
 			factory.addAdvice(new DefaultMethodInvokingMethodInterceptor());
 		}
 
-		factory.addAdvice(new TargetClassAwareMethodInterceptor(source.getClass()));
+		factory.addAdvice(new TargetAwareMethodInterceptor(source.getClass()));
 		factory.addAdvice(getMethodInterceptor(source, projectionType));
 
 		return (T) factory.getProxy(getClass().getClassLoader());
@@ -152,45 +150,37 @@ protected boolean isInputProperty(PropertyDescriptor descriptor) {
 		return true;
 	}
 
-	/**
-	 * Extension of {@link org.springframework.aop.TargetClassAware} to be able to ignore the getter on JSON rendering.
-	 * 
-	 * @author Oliver Gierke
-	 */
-	public static interface TargetClassAware extends org.springframework.aop.TargetClassAware {
-
-		@JsonIgnore
-		Class<?> getTargetClass();
-	}
-
 	/**
 	 * Custom {@link MethodInterceptor} to expose the proxy target class even if we set
 	 * {@link ProxyFactory#setOpaque(boolean)} to true to prevent properties on {@link Advised} to be rendered.
 	 * 
 	 * @author Oliver Gierke
 	 */
-	private static class TargetClassAwareMethodInterceptor implements MethodInterceptor {
+	private static class TargetAwareMethodInterceptor implements MethodInterceptor {
 
 		private static final Method GET_TARGET_CLASS_METHOD;
-		private final Class<?> targetClass;
+		private static final Method GET_TARGET_METHOD;
+
+		private final Class<?> targetType;
 
 		static {
 			try {
-				GET_TARGET_CLASS_METHOD = TargetClassAware.class.getMethod("getTargetClass");
+				GET_TARGET_CLASS_METHOD = TargetAware.class.getMethod("getTargetClass");
+				GET_TARGET_METHOD = TargetAware.class.getMethod("getTarget");
 			} catch (NoSuchMethodException e) {
 				throw new IllegalStateException(e);
 			}
 		}
 
 		/**
-		 * Creates a new {@link TargetClassAwareMethodInterceptor} with the given target class.
+		 * Creates a new {@link TargetAwareMethodInterceptor} with the given target class.
 		 * 
-		 * @param targetClass must not be {@literal null}.
+		 * @param targetType must not be {@literal null}.
 		 */
-		public TargetClassAwareMethodInterceptor(Class<?> targetClass) {
+		public TargetAwareMethodInterceptor(Class<?> targetType) {
 
-			Assert.notNull(targetClass, "Target class must not be null!");
-			this.targetClass = targetClass;
+			Assert.notNull(targetType, "Target type must not be null!");
+			this.targetType = targetType;
 		}
 
 		/* 
@@ -201,7 +191,9 @@ public TargetClassAwareMethodInterceptor(Class<?> targetClass) {
 		public Object invoke(MethodInvocation invocation) throws Throwable {
 
 			if (invocation.getMethod().equals(GET_TARGET_CLASS_METHOD)) {
-				return targetClass;
+				return targetType;
+			} else if (invocation.getMethod().equals(GET_TARGET_METHOD)) {
+				return invocation.getThis();
 			}
 
 			return invocation.proceed();

src/main/java/org/springframework/data/projection/TargetAware.java

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2015 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.projection;
+
+import org.springframework.aop.RawTargetAccess;
+
+import com.fasterxml.jackson.annotation.JsonIgnore;
+
+/**
+ * Extension of {@link org.springframework.aop.TargetClassAware} to be able to ignore the getter on JSON rendering.
+ * 
+ * @author Oliver Gierke
+ */
+public interface TargetAware extends org.springframework.aop.TargetClassAware, RawTargetAccess {
+
+	/**
+	 * Returns the type of the proxy target.
+	 * 
+	 * @return will never be {@literal null}.
+	 */
+	@JsonIgnore
+	Class<?> getTargetClass();
+
+	/**
+	 * Returns the proxy target.
+	 * 
+	 * @return will never be {@literal null}.
+	 */
+	@JsonIgnore
+	Object getTarget();
+}

src/test/java/org/springframework/data/projection/ProxyProjectionFactoryUnitTests.java

@@ -176,6 +176,18 @@ public void invokesDefaultMethodOnProxy() {
 		assertThat(advisors[0].getAdvice(), is(instanceOf(DefaultMethodInvokingMethodInterceptor.class)));
 	}
 
+	/**
+	 * @see DATACMNS-648
+	 */
+	@Test
+	public void exposesProxyTarget() {
+
+		CustomerExcerpt excerpt = factory.createProjection(CustomerExcerpt.class);
+
+		assertThat(excerpt, is(instanceOf(TargetAware.class)));
+		assertThat(((TargetAware) excerpt).getTarget(), is(instanceOf(Map.class)));
+	}
+
 	static class Customer {
 
 		public String firstname, lastname;