001/*
002 * Copyright 2002-2014 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.method.annotation;
018
019import org.springframework.core.MethodParameter;
020import org.springframework.ui.Model;
021import org.springframework.web.bind.support.WebDataBinderFactory;
022import org.springframework.web.context.request.NativeWebRequest;
023import org.springframework.web.method.support.HandlerMethodArgumentResolver;
024import org.springframework.web.method.support.HandlerMethodReturnValueHandler;
025import org.springframework.web.method.support.ModelAndViewContainer;
026
027/**
028 * Resolves {@link Model} arguments and handles {@link Model} return values.
029 *
030 * <p>A {@link Model} return type has a set purpose. Therefore this handler
031 * should be configured ahead of handlers that support any return value type
032 * annotated with {@code @ModelAttribute} or {@code @ResponseBody} to ensure
033 * they don't take over.
034 *
035 * @author Rossen Stoyanchev
036 * @since 3.1
037 */
038public class ModelMethodProcessor implements HandlerMethodArgumentResolver, HandlerMethodReturnValueHandler {
039
040        @Override
041        public boolean supportsParameter(MethodParameter parameter) {
042                return Model.class.isAssignableFrom(parameter.getParameterType());
043        }
044
045        @Override
046        public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
047                        NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {
048
049                return mavContainer.getModel();
050        }
051
052        @Override
053        public boolean supportsReturnType(MethodParameter returnType) {
054                return Model.class.isAssignableFrom(returnType.getParameterType());
055        }
056
057        @Override
058        public void handleReturnValue(Object returnValue, MethodParameter returnType,
059                        ModelAndViewContainer mavContainer, NativeWebRequest webRequest) throws Exception {
060
061                if (returnValue == null) {
062                        return;
063                }
064                else if (returnValue instanceof Model) {
065                        mavContainer.addAllAttributes(((Model) returnValue).asMap());
066                }
067                else {
068                        // should not happen
069                        throw new UnsupportedOperationException("Unexpected return type: " +
070                                        returnType.getParameterType().getName() + " in method: " + returnType.getMethod());
071                }
072        }
073
074}