001/*
002 * Copyright 2002-2019 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.messaging.handler.annotation.reactive;
018
019import java.util.List;
020import java.util.Map;
021
022import org.apache.commons.logging.Log;
023import org.apache.commons.logging.LogFactory;
024
025import org.springframework.beans.factory.config.ConfigurableBeanFactory;
026import org.springframework.core.MethodParameter;
027import org.springframework.core.convert.ConversionService;
028import org.springframework.lang.Nullable;
029import org.springframework.messaging.Message;
030import org.springframework.messaging.MessageHandlingException;
031import org.springframework.messaging.handler.annotation.Header;
032import org.springframework.messaging.support.NativeMessageHeaderAccessor;
033import org.springframework.util.Assert;
034
035/**
036 * Resolver for {@link Header @Header} arguments. Headers are resolved from
037 * either the top-level header map or the nested
038 * {@link NativeMessageHeaderAccessor native} header map.
039 *
040 * @author Rossen Stoyanchev
041 * @since 5.2
042 * @see HeadersMethodArgumentResolver
043 * @see NativeMessageHeaderAccessor
044 */
045public class HeaderMethodArgumentResolver extends AbstractNamedValueMethodArgumentResolver {
046
047        private static final Log logger = LogFactory.getLog(HeaderMethodArgumentResolver.class);
048
049
050        public HeaderMethodArgumentResolver(
051                        ConversionService conversionService, @Nullable ConfigurableBeanFactory beanFactory) {
052
053                super(conversionService, beanFactory);
054        }
055
056
057        @Override
058        public boolean supportsParameter(MethodParameter parameter) {
059                return parameter.hasParameterAnnotation(Header.class);
060        }
061
062        @Override
063        protected NamedValueInfo createNamedValueInfo(MethodParameter parameter) {
064                Header annot = parameter.getParameterAnnotation(Header.class);
065                Assert.state(annot != null, "No Header annotation");
066                return new HeaderNamedValueInfo(annot);
067        }
068
069        @Override
070        @Nullable
071        protected Object resolveArgumentInternal(MethodParameter parameter, Message<?> message, String name) {
072
073                Object headerValue = message.getHeaders().get(name);
074                Object nativeHeaderValue = getNativeHeaderValue(message, name);
075
076                if (headerValue != null && nativeHeaderValue != null) {
077                        if (logger.isDebugEnabled()) {
078                                logger.debug("A value was found for '" + name + "', in both the top level header map " +
079                                                "and also in the nested map for native headers. Using the value from top level map. " +
080                                                "Use 'nativeHeader.myHeader' to resolve the native header.");
081                        }
082                }
083
084                return (headerValue != null ? headerValue : nativeHeaderValue);
085        }
086
087        @Nullable
088        private Object getNativeHeaderValue(Message<?> message, String name) {
089                Map<String, List<String>> nativeHeaders = getNativeHeaders(message);
090                if (name.startsWith("nativeHeaders.")) {
091                        name = name.substring("nativeHeaders.".length());
092                }
093                if (nativeHeaders == null || !nativeHeaders.containsKey(name)) {
094                        return null;
095                }
096                List<?> nativeHeaderValues = nativeHeaders.get(name);
097                return (nativeHeaderValues.size() == 1 ? nativeHeaderValues.get(0) : nativeHeaderValues);
098        }
099
100        @SuppressWarnings("unchecked")
101        @Nullable
102        private Map<String, List<String>> getNativeHeaders(Message<?> message) {
103                return (Map<String, List<String>>) message.getHeaders().get(NativeMessageHeaderAccessor.NATIVE_HEADERS);
104        }
105
106        @Override
107        protected void handleMissingValue(String headerName, MethodParameter parameter, Message<?> message) {
108                throw new MessageHandlingException(message, "Missing header '" + headerName +
109                                "' for method parameter type [" + parameter.getParameterType() + "]");
110        }
111
112
113        private static final class HeaderNamedValueInfo extends NamedValueInfo {
114
115                private HeaderNamedValueInfo(Header annotation) {
116                        super(annotation.name(), annotation.required(), annotation.defaultValue());
117                }
118        }
119
120}