001/*
002 * Copyright 2002-2017 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.web.servlet.mvc.method.annotation;
018
019import org.springframework.beans.factory.BeanFactory;
020import org.springframework.core.MethodParameter;
021import org.springframework.lang.Nullable;
022import org.springframework.web.context.request.NativeWebRequest;
023import org.springframework.web.context.request.async.WebAsyncTask;
024import org.springframework.web.context.request.async.WebAsyncUtils;
025import org.springframework.web.method.support.HandlerMethodReturnValueHandler;
026import org.springframework.web.method.support.ModelAndViewContainer;
027
028/**
029 * Handles return values of type {@link WebAsyncTask}.
030 *
031 * @author Rossen Stoyanchev
032 * @since 3.2
033 */
034public class AsyncTaskMethodReturnValueHandler implements HandlerMethodReturnValueHandler {
035
036        @Nullable
037        private final BeanFactory beanFactory;
038
039
040        public AsyncTaskMethodReturnValueHandler(@Nullable BeanFactory beanFactory) {
041                this.beanFactory = beanFactory;
042        }
043
044
045        @Override
046        public boolean supportsReturnType(MethodParameter returnType) {
047                return WebAsyncTask.class.isAssignableFrom(returnType.getParameterType());
048        }
049
050        @Override
051        public void handleReturnValue(@Nullable Object returnValue, MethodParameter returnType,
052                        ModelAndViewContainer mavContainer, NativeWebRequest webRequest) throws Exception {
053
054                if (returnValue == null) {
055                        mavContainer.setRequestHandled(true);
056                        return;
057                }
058
059                WebAsyncTask<?> webAsyncTask = (WebAsyncTask<?>) returnValue;
060                if (this.beanFactory != null) {
061                        webAsyncTask.setBeanFactory(this.beanFactory);
062                }
063                WebAsyncUtils.getAsyncManager(webRequest).startCallableProcessing(webAsyncTask, mavContainer);
064        }
065
066}