org.springframework.web.servlet.mvc.method.annotation.MatrixVariableMapMethodArgumentResolver.java Source code

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Here is the source code for org.springframework.web.servlet.mvc.method.annotation.MatrixVariableMapMethodArgumentResolver.java

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/*
 * Copyright 2002-2018 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
 * limitations under the License.
 */

package org.springframework.web.servlet.mvc.method.annotation;

import java.util.Collections;
import java.util.List;
import java.util.Map;

import org.springframework.core.MethodParameter;
import org.springframework.core.ResolvableType;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.CollectionUtils;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.annotation.MatrixVariable;
import org.springframework.web.bind.annotation.ValueConstants;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;
import org.springframework.web.context.request.RequestAttributes;
import org.springframework.web.method.support.HandlerMethodArgumentResolver;
import org.springframework.web.method.support.ModelAndViewContainer;
import org.springframework.web.servlet.HandlerMapping;

/**
 * Resolves arguments of type {@link Map} annotated with {@link MatrixVariable @MatrixVariable}
 * where the annotation does not specify a name. In other words the purpose of this resolver
 * is to provide access to multiple matrix variables, either all or associated with a specific
 * path variable.
 *
 * <p>When a name is specified, an argument of type Map is considered to be a single attribute
 * with a Map value, and is resolved by {@link MatrixVariableMethodArgumentResolver} instead.
 *
 * @author Rossen Stoyanchev
 * @since 3.2
 */
public class MatrixVariableMapMethodArgumentResolver implements HandlerMethodArgumentResolver {

    @Override
    public boolean supportsParameter(MethodParameter parameter) {
        MatrixVariable matrixVariable = parameter.getParameterAnnotation(MatrixVariable.class);
        return (matrixVariable != null && Map.class.isAssignableFrom(parameter.getParameterType())
                && !StringUtils.hasText(matrixVariable.name()));
    }

    @Override
    @Nullable
    public Object resolveArgument(MethodParameter parameter, @Nullable ModelAndViewContainer mavContainer,
            NativeWebRequest request, @Nullable WebDataBinderFactory binderFactory) throws Exception {

        @SuppressWarnings("unchecked")
        Map<String, MultiValueMap<String, String>> matrixVariables = (Map<String, MultiValueMap<String, String>>) request
                .getAttribute(HandlerMapping.MATRIX_VARIABLES_ATTRIBUTE, RequestAttributes.SCOPE_REQUEST);

        if (CollectionUtils.isEmpty(matrixVariables)) {
            return Collections.emptyMap();
        }

        MultiValueMap<String, String> map = new LinkedMultiValueMap<>();
        MatrixVariable ann = parameter.getParameterAnnotation(MatrixVariable.class);
        Assert.state(ann != null, "No MatrixVariable annotation");
        String pathVariable = ann.pathVar();

        if (!pathVariable.equals(ValueConstants.DEFAULT_NONE)) {
            MultiValueMap<String, String> mapForPathVariable = matrixVariables.get(pathVariable);
            if (mapForPathVariable == null) {
                return Collections.emptyMap();
            }
            map.putAll(mapForPathVariable);
        } else {
            for (MultiValueMap<String, String> vars : matrixVariables.values()) {
                vars.forEach((name, values) -> {
                    for (String value : values) {
                        map.add(name, value);
                    }
                });
            }
        }

        return (isSingleValueMap(parameter) ? map.toSingleValueMap() : map);
    }

    private boolean isSingleValueMap(MethodParameter parameter) {
        if (!MultiValueMap.class.isAssignableFrom(parameter.getParameterType())) {
            ResolvableType[] genericTypes = ResolvableType.forMethodParameter(parameter).getGenerics();
            if (genericTypes.length == 2) {
                return !List.class.isAssignableFrom(genericTypes[1].toClass());
            }
        }
        return false;
    }

}