/*
 * Copyright 2002-2020 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
 *
 *      https://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
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package org.springframework.web.method.annotation;

import java.util.Map;

import org.springframework.core.MethodParameter;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.HandlerMethodReturnValueHandler;
import org.springframework.web.method.support.ModelAndViewContainer;

Resolves Map method arguments and handles Map return values.

A Map return value can be interpreted in more than one ways depending on the presence of annotations like @ModelAttribute or @ResponseBody. As of 5.2 this resolver returns false if the parameter is annotated.

Author:Rossen Stoyanchev
Since:3.1
/** * Resolves {@link Map} method arguments and handles {@link Map} return values. * * <p>A Map return value can be interpreted in more than one ways depending * on the presence of annotations like {@code @ModelAttribute} or * {@code @ResponseBody}. As of 5.2 this resolver returns false if the * parameter is annotated. * * @author Rossen Stoyanchev * @since 3.1 */
public class MapMethodProcessor implements HandlerMethodArgumentResolver, HandlerMethodReturnValueHandler { @Override public boolean supportsParameter(MethodParameter parameter) { return (Map.class.isAssignableFrom(parameter.getParameterType()) && parameter.getParameterAnnotations().length == 0); } @Override @Nullable public Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer, NativeWebRequest webRequest, @Nullable WebDataBinderFactory binderFactory) throws Exception { Assert.state(mavContainer != null, "ModelAndViewContainer is required for model exposure"); return mavContainer.getModel(); } @Override public boolean supportsReturnType(MethodParameter returnType) { return Map.class.isAssignableFrom(returnType.getParameterType()); } @Override @SuppressWarnings({"rawtypes", "unchecked"}) public void handleReturnValue(@Nullable Object returnValue, MethodParameter returnType, ModelAndViewContainer mavContainer, NativeWebRequest webRequest) throws Exception { if (returnValue instanceof Map){ mavContainer.addAllAttributes((Map) returnValue); } else if (returnValue != null) { // should not happen throw new UnsupportedOperationException("Unexpected return type [" + returnType.getParameterType().getName() + "] in method: " + returnType.getMethod()); } } }