Support ListenableFuture on @RequestMapping methods

Issue: SPR-11695

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ListenableFutureReturnValueHandler.java

@@ -0,0 +1,69 @@
+/*
+ * Copyright 2002-2014 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.method.annotation;
+
+import org.springframework.core.MethodParameter;
+import org.springframework.util.concurrent.ListenableFuture;
+import org.springframework.util.concurrent.ListenableFutureCallback;
+import org.springframework.web.context.request.NativeWebRequest;
+import org.springframework.web.context.request.async.DeferredResult;
+import org.springframework.web.context.request.async.WebAsyncUtils;
+import org.springframework.web.method.support.HandlerMethodReturnValueHandler;
+import org.springframework.web.method.support.ModelAndViewContainer;
+
+/**
+ * Handles return values of type
+ * {@link org.springframework.util.concurrent.ListenableFuture}.
+ *
+ * @author Rossen Stoyanchev
+ * @since 4.1
+ */
+public class ListenableFutureReturnValueHandler implements HandlerMethodReturnValueHandler {
+
+	@Override
+	public boolean supportsReturnType(MethodParameter returnType) {
+		Class<?> paramType = returnType.getParameterType();
+		return ListenableFuture.class.isAssignableFrom(paramType);
+	}
+
+	@Override
+	public void handleReturnValue(Object returnValue,
+			MethodParameter returnType, ModelAndViewContainer mavContainer,
+			NativeWebRequest webRequest) throws Exception {
+
+		if (returnValue == null) {
+			mavContainer.setRequestHandled(true);
+			return;
+		}
+
+		DeferredResult<Object> deferredResult = new DeferredResult<Object>();
+		WebAsyncUtils.getAsyncManager(webRequest).startDeferredResultProcessing(deferredResult, mavContainer);
+
+		ListenableFuture<?> future = (ListenableFuture<?>) returnValue;
+		future.addCallback(new ListenableFutureCallback<Object>() {
+			@Override
+			public void onSuccess(Object result) {
+				deferredResult.setResult(result);
+			}
+			@Override
+			public void onFailure(Throwable ex) {
+				deferredResult.setErrorResult(ex);
+			}
+		});
+	}
+
+}

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/RequestMappingHandlerAdapter.java

@@ -588,6 +588,7 @@ public class RequestMappingHandlerAdapter extends AbstractHandlerMethodAdapter
 		handlers.add(new CallableMethodReturnValueHandler());
 		handlers.add(new DeferredResultMethodReturnValueHandler());
 		handlers.add(new AsyncTaskMethodReturnValueHandler(this.beanFactory));
+		handlers.add(new ListenableFutureReturnValueHandler());
 
 		// Annotation-based return value types
 		handlers.add(new ModelAttributeMethodProcessor(false));