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.lang.reflect.Method;
020import java.util.Map;
021
022import org.springframework.core.MethodParameter;
023import org.springframework.lang.Nullable;
024import org.springframework.messaging.Message;
025import org.springframework.messaging.MessageHeaders;
026import org.springframework.messaging.handler.annotation.Headers;
027import org.springframework.messaging.handler.invocation.reactive.SyncHandlerMethodArgumentResolver;
028import org.springframework.messaging.support.MessageHeaderAccessor;
029import org.springframework.util.ReflectionUtils;
030
031/**
032 * Argument resolver for headers. Resolves the following method parameters:
033 * <ul>
034 * <li>{@link Headers @Headers} {@link Map}
035 * <li>{@link MessageHeaders}
036 * <li>{@link MessageHeaderAccessor}
037 * </ul>
038 *
039 * @author Rossen Stoyanchev
040 * @since 5.2
041 */
042public class HeadersMethodArgumentResolver implements SyncHandlerMethodArgumentResolver {
043
044        @Override
045        public boolean supportsParameter(MethodParameter parameter) {
046                Class<?> paramType = parameter.getParameterType();
047                return ((parameter.hasParameterAnnotation(Headers.class) && Map.class.isAssignableFrom(paramType)) ||
048                                MessageHeaders.class == paramType || MessageHeaderAccessor.class.isAssignableFrom(paramType));
049        }
050
051        @Override
052        @Nullable
053        public Object resolveArgumentValue(MethodParameter parameter, Message<?> message) {
054                Class<?> paramType = parameter.getParameterType();
055                if (Map.class.isAssignableFrom(paramType)) {
056                        return message.getHeaders();
057                }
058                else if (MessageHeaderAccessor.class == paramType) {
059                        MessageHeaderAccessor accessor = MessageHeaderAccessor.getAccessor(message, MessageHeaderAccessor.class);
060                        return accessor != null ? accessor : new MessageHeaderAccessor(message);
061                }
062                else if (MessageHeaderAccessor.class.isAssignableFrom(paramType)) {
063                        MessageHeaderAccessor accessor = MessageHeaderAccessor.getAccessor(message, MessageHeaderAccessor.class);
064                        if (accessor != null && paramType.isAssignableFrom(accessor.getClass())) {
065                                return accessor;
066                        }
067                        else {
068                                Method method = ReflectionUtils.findMethod(paramType, "wrap", Message.class);
069                                if (method == null) {
070                                        throw new IllegalStateException(
071                                                        "Cannot create accessor of type " + paramType + " for message " + message);
072                                }
073                                return ReflectionUtils.invokeMethod(method, null, message);
074                        }
075                }
076                else {
077                        throw new IllegalStateException("Unexpected parameter of type " + paramType +
078                                        " in method " + parameter.getMethod() + ". ");
079                }
080        }
081
082}