SPR-5426 - Allow for custom processing or result objects returned from handler/controller methods

org.springframework.web.servlet/src/main/java/org/springframework/web/servlet/mvc/annotation/AnnotationMethodHandlerAdapter.java

@@ -150,6 +150,8 @@ public class AnnotationMethodHandlerAdapter extends WebContentGenerator implemen
 
 	private WebArgumentResolver[] customArgumentResolvers;
 
+	private ModelAndViewResolver[] customModelAndViewResolvers;
+
 	private final Map<Class<?>, ServletHandlerMethodResolver> methodResolverCache =
 			new ConcurrentHashMap<Class<?>, ServletHandlerMethodResolver>();
 
@@ -269,7 +271,7 @@ public class AnnotationMethodHandlerAdapter extends WebContentGenerator implemen
 	}
 
 	/**
-	 * Set a custom ArgumentResolvers to use for special method parameter types. Such a custom ArgumentResolver will kick
+	 * Set a custom WebArgumentResolvers to use for special method parameter types. Such a custom WebArgumentResolver will kick
 	 * in first, having a chance to resolve an argument value before the standard argument handling kicks in.
 	 */
 	public void setCustomArgumentResolver(WebArgumentResolver argumentResolver) {
@@ -277,13 +279,29 @@ public class AnnotationMethodHandlerAdapter extends WebContentGenerator implemen
 	}
 
 	/**
-	 * Set one or more custom ArgumentResolvers to use for special method parameter types. Any such custom ArgumentResolver
+	 * Set one or more custom WebArgumentResolvers to use for special method parameter types. Any such custom WebArgumentResolver
 	 * will kick in first, having a chance to resolve an argument value before the standard argument handling kicks in.
 	 */
 	public void setCustomArgumentResolvers(WebArgumentResolver[] argumentResolvers) {
 		this.customArgumentResolvers = argumentResolvers;
 	}
 
+	/**
+	 * Set a custom ModelAndViewResolvers to use for special method return types. Such a custom ModelAndViewResolver will kick
+	 * in first, having a chance to resolve an return value before the standard ModelAndView handling kicks in.
+	 */
+	public void setCustomModelAndViewResolver(ModelAndViewResolver customModelAndViewResolver) {
+		this.customModelAndViewResolvers = new ModelAndViewResolver[]{customModelAndViewResolver};
+	}
+
+	/**
+	 * Set one or more custom ModelAndViewResolvers to use for special method return types. Any such custom ModelAndViewResolver
+	 * will kick in first, having a chance to resolve an return value before the standard ModelAndView handling kicks in.
+	 */
+	public void setCustomModelAndViewResolvers(ModelAndViewResolver[] customModelAndViewResolvers) {
+		this.customModelAndViewResolvers = customModelAndViewResolvers;
+	}
+
 	/**
 	 * Set the message body converters to use. These converters are used to convert from and to HTTP requests and
 	 * responses.
@@ -673,6 +691,16 @@ public class AnnotationMethodHandlerAdapter extends WebContentGenerator implemen
 				ExtendedModelMap implicitModel,
 				ServletWebRequest webRequest) {
 
+			// Invoke custom resolvers if present...
+			if (customModelAndViewResolvers != null) {
+				for (ModelAndViewResolver mavResolver : customModelAndViewResolvers) {
+					ModelAndView mav = mavResolver
+							.resolveModelAndView(handlerMethod, handlerType, returnValue, implicitModel, webRequest);
+					if (mav != ModelAndViewResolver.UNRESOLVED) {
+						return mav;
+					}
+				}
+			}
 			if (handlerMethod.isAnnotationPresent(ResponseStatus.class)) {
 				ResponseStatus responseStatus = handlerMethod.getAnnotation(ResponseStatus.class);
 				HttpServletResponse response = webRequest.getResponse();

org.springframework.web.servlet/src/main/java/org/springframework/web/servlet/mvc/annotation/ModelAndViewResolver.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2002-2009 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.web.servlet.mvc.annotation;
+
+import java.lang.reflect.Method;
+
+import org.springframework.ui.ExtendedModelMap;
+import org.springframework.web.context.request.NativeWebRequest;
+import org.springframework.web.servlet.ModelAndView;
+
+/**
+ * SPI for resolving custom return values from a specific handler method. Typically implemented to detect special return
+ * types, resolving well-known result values for them.
+ *
+ * <p>A typical implementation could look like as follows:
+ *
+ * <pre class="code">
+ * public class MyModelAndViewResolver implements ModelAndViewResolver {
+ *
+ *   public ModelAndView resolveModelAndView(Method handlerMethod,
+ *		   			Class handlerType,
+ *		   			Object returnValue,
+ *		 			ExtendedModelMap implicitModel,
+ *		 			NativeWebRequest webRequest) {
+ *     if (returnValue instanceof MySpecialRetVal.class)) {
+ *       return new MySpecialRetVal(returnValue);
+ *     }
+ *     return UNRESOLVED;
+ *   }
+ * }</pre>
+ *
+ * @author Arjen Poutsma
+ * @see org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter#setCustomModelAndViewResolvers
+ * @see org.springframework.web.portlet.mvc.annotation.AnnotationMethodHandlerAdapter#setCustomModelAndViewResolvers
+ * @since 3.0
+ */
+public interface ModelAndViewResolver {
+
+	/** Marker to be returned when the resolver does not know how to handle the given method parameter. */
+	ModelAndView UNRESOLVED = new ModelAndView();
+
+	ModelAndView resolveModelAndView(Method handlerMethod,
+			Class handlerType,
+			Object returnValue,
+			ExtendedModelMap implicitModel,
+			NativeWebRequest webRequest);
+}