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.reactive.result.method.annotation;
018
019import java.util.List;
020import java.util.Map;
021
022import org.springframework.beans.factory.config.ConfigurableBeanFactory;
023import org.springframework.core.MethodParameter;
024import org.springframework.core.ReactiveAdapterRegistry;
025import org.springframework.core.convert.ConversionService;
026import org.springframework.lang.Nullable;
027import org.springframework.util.Assert;
028import org.springframework.web.bind.annotation.RequestHeader;
029import org.springframework.web.server.ServerWebExchange;
030import org.springframework.web.server.ServerWebInputException;
031
032/**
033 * Resolves method arguments annotated with {@code @RequestHeader} except for
034 * {@link Map} arguments. See {@link RequestHeaderMapMethodArgumentResolver} for
035 * details on {@link Map} arguments annotated with {@code @RequestHeader}.
036 *
037 * <p>An {@code @RequestHeader} is a named value resolved from a request header.
038 * It has a required flag and a default value to fall back on when the request
039 * header does not exist.
040 *
041 * <p>A {@link ConversionService} is invoked to apply type conversion to resolved
042 * request header values that don't yet match the method parameter type.
043 *
044 * @author Rossen Stoyanchev
045 * @since 5.0
046 * @see RequestHeaderMapMethodArgumentResolver
047 */
048public class RequestHeaderMethodArgumentResolver extends AbstractNamedValueSyncArgumentResolver {
049
050        /**
051         * Create a new {@link RequestHeaderMethodArgumentResolver} instance.
052         * @param factory a bean factory to use for resolving {@code ${...}}
053         * placeholder and {@code #{...}} SpEL expressions in default values;
054         * or {@code null} if default values are not expected to have expressions
055         * @param registry for checking reactive type wrappers
056         */
057        public RequestHeaderMethodArgumentResolver(@Nullable ConfigurableBeanFactory factory,
058                        ReactiveAdapterRegistry registry) {
059
060                super(factory, registry);
061        }
062
063
064        @Override
065        public boolean supportsParameter(MethodParameter param) {
066                return checkAnnotatedParamNoReactiveWrapper(param, RequestHeader.class, this::singleParam);
067        }
068
069        private boolean singleParam(RequestHeader annotation, Class<?> type) {
070                return !Map.class.isAssignableFrom(type);
071        }
072
073        @Override
074        protected NamedValueInfo createNamedValueInfo(MethodParameter parameter) {
075                RequestHeader ann = parameter.getParameterAnnotation(RequestHeader.class);
076                Assert.state(ann != null, "No RequestHeader annotation");
077                return new RequestHeaderNamedValueInfo(ann);
078        }
079
080        @Override
081        protected Object resolveNamedValue(String name, MethodParameter parameter, ServerWebExchange exchange) {
082                List<String> headerValues = exchange.getRequest().getHeaders().get(name);
083                Object result = null;
084                if (headerValues != null) {
085                        result = (headerValues.size() == 1 ? headerValues.get(0) : headerValues);
086                }
087                return result;
088        }
089
090        @Override
091        protected void handleMissingValue(String name, MethodParameter parameter) {
092                String type = parameter.getNestedParameterType().getSimpleName();
093                throw new ServerWebInputException("Missing request header '" + name + "' " +
094                                "for method parameter of type " + type, parameter);
095        }
096
097
098        private static final class RequestHeaderNamedValueInfo extends NamedValueInfo {
099
100                private RequestHeaderNamedValueInfo(RequestHeader annotation) {
101                        super(annotation.name(), annotation.required(), annotation.defaultValue());
102                }
103        }
104
105}