001/*
002 * Copyright 2002-2020 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 java.util.Map;
020
021import org.springframework.core.MethodParameter;
022import org.springframework.lang.Nullable;
023import org.springframework.util.Assert;
024import org.springframework.web.bind.support.WebDataBinderFactory;
025import org.springframework.web.context.request.NativeWebRequest;
026import org.springframework.web.method.support.HandlerMethodArgumentResolver;
027import org.springframework.web.method.support.HandlerMethodReturnValueHandler;
028import org.springframework.web.method.support.ModelAndViewContainer;
029
030/**
031 * Resolves {@link Map} method arguments and handles {@link Map} return values.
032 *
033 * <p>A Map return value can be interpreted in more than one ways depending
034 * on the presence of annotations like {@code @ModelAttribute} or
035 * {@code @ResponseBody}. As of 5.2 this resolver returns false if the
036 * parameter is annotated.
037 *
038 * @author Rossen Stoyanchev
039 * @since 3.1
040 */
041public class MapMethodProcessor implements HandlerMethodArgumentResolver, HandlerMethodReturnValueHandler {
042
043        @Override
044        public boolean supportsParameter(MethodParameter parameter) {
045                return (Map.class.isAssignableFrom(parameter.getParameterType()) &&
046                                parameter.getParameterAnnotations().length == 0);
047        }
048
049        @Override
050        @Nullable
051        public Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
052                        NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception {
053
054                Assert.state(mavContainer != null, "ModelAndViewContainer is required for model exposure");
055                return mavContainer.getModel();
056        }
057
058        @Override
059        public boolean supportsReturnType(MethodParameter returnType) {
060                return Map.class.isAssignableFrom(returnType.getParameterType());
061        }
062
063        @Override
064        @SuppressWarnings({"rawtypes", "unchecked"})
065        public void handleReturnValue(@Nullable Object returnValue, MethodParameter returnType,
066                        ModelAndViewContainer mavContainer, NativeWebRequest webRequest) throws Exception {
067
068                if (returnValue instanceof Map){
069                        mavContainer.addAllAttributes((Map) returnValue);
070                }
071                else if (returnValue != null) {
072                        // should not happen
073                        throw new UnsupportedOperationException("Unexpected return type [" +
074                                        returnType.getParameterType().getName() + "] in method: " + returnType.getMethod());
075                }
076        }
077
078}