001/*
002 * Copyright 2002-2018 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.beans.factory.config.ConfigurableBeanFactory;
022import org.springframework.core.MethodParameter;
023import org.springframework.lang.Nullable;
024import org.springframework.util.Assert;
025import org.springframework.web.bind.MissingRequestHeaderException;
026import org.springframework.web.bind.ServletRequestBindingException;
027import org.springframework.web.bind.WebDataBinder;
028import org.springframework.web.bind.annotation.RequestHeader;
029import org.springframework.web.context.request.NativeWebRequest;
030
031/**
032 * Resolves method arguments annotated with {@code @RequestHeader} except for
033 * {@link Map} arguments. See {@link RequestHeaderMapMethodArgumentResolver} for
034 * details on {@link Map} arguments annotated with {@code @RequestHeader}.
035 *
036 * <p>An {@code @RequestHeader} is a named value resolved from a request header.
037 * It has a required flag and a default value to fall back on when the request
038 * header does not exist.
039 *
040 * <p>A {@link WebDataBinder} is invoked to apply type conversion to resolved
041 * request header values that don't yet match the method parameter type.
042 *
043 * @author Arjen Poutsma
044 * @author Rossen Stoyanchev
045 * @since 3.1
046 */
047public class RequestHeaderMethodArgumentResolver extends AbstractNamedValueMethodArgumentResolver {
048
049        /**
050         * Create a new {@link RequestHeaderMethodArgumentResolver} instance.
051         * @param beanFactory a bean factory to use for resolving  ${...}
052         * placeholder and #{...} SpEL expressions in default values;
053         * or {@code null} if default values are not expected to have expressions
054         */
055        public RequestHeaderMethodArgumentResolver(@Nullable ConfigurableBeanFactory beanFactory) {
056                super(beanFactory);
057        }
058
059
060        @Override
061        public boolean supportsParameter(MethodParameter parameter) {
062                return (parameter.hasParameterAnnotation(RequestHeader.class) &&
063                                !Map.class.isAssignableFrom(parameter.nestedIfOptional().getNestedParameterType()));
064        }
065
066        @Override
067        protected NamedValueInfo createNamedValueInfo(MethodParameter parameter) {
068                RequestHeader ann = parameter.getParameterAnnotation(RequestHeader.class);
069                Assert.state(ann != null, "No RequestHeader annotation");
070                return new RequestHeaderNamedValueInfo(ann);
071        }
072
073        @Override
074        @Nullable
075        protected Object resolveName(String name, MethodParameter parameter, NativeWebRequest request) throws Exception {
076                String[] headerValues = request.getHeaderValues(name);
077                if (headerValues != null) {
078                        return (headerValues.length == 1 ? headerValues[0] : headerValues);
079                }
080                else {
081                        return null;
082                }
083        }
084
085        @Override
086        protected void handleMissingValue(String name, MethodParameter parameter) throws ServletRequestBindingException {
087                throw new MissingRequestHeaderException(name, parameter);
088        }
089
090
091        private static final class RequestHeaderNamedValueInfo extends NamedValueInfo {
092
093                private RequestHeaderNamedValueInfo(RequestHeader annotation) {
094                        super(annotation.name(), annotation.required(), annotation.defaultValue());
095                }
096        }
097
098}