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.messaging.handler.annotation.support; 018 019import java.lang.reflect.Method; 020import java.util.Map; 021 022import org.springframework.core.MethodParameter; 023import org.springframework.messaging.Message; 024import org.springframework.messaging.MessageHeaders; 025import org.springframework.messaging.handler.annotation.Headers; 026import org.springframework.messaging.handler.invocation.HandlerMethodArgumentResolver; 027import org.springframework.messaging.support.MessageHeaderAccessor; 028import org.springframework.util.ReflectionUtils; 029 030/** 031 * Resolves the following method parameters: 032 * <ul> 033 * <li>Parameters assignable to {@link Map} annotated with {@link Headers @Headers} 034 * <li>Parameters of type {@link MessageHeaders} 035 * <li>Parameters assignable to {@link MessageHeaderAccessor} 036 * </ul> 037 * 038 * @author Rossen Stoyanchev 039 * @since 4.0 040 */ 041public class HeadersMethodArgumentResolver implements HandlerMethodArgumentResolver { 042 043 @Override 044 public boolean supportsParameter(MethodParameter parameter) { 045 Class<?> paramType = parameter.getParameterType(); 046 return ((parameter.hasParameterAnnotation(Headers.class) && Map.class.isAssignableFrom(paramType)) || 047 MessageHeaders.class == paramType || MessageHeaderAccessor.class.isAssignableFrom(paramType)); 048 } 049 050 @Override 051 public Object resolveArgument(MethodParameter parameter, Message<?> message) throws Exception { 052 Class<?> paramType = parameter.getParameterType(); 053 if (Map.class.isAssignableFrom(paramType)) { 054 return message.getHeaders(); 055 } 056 else if (MessageHeaderAccessor.class == paramType) { 057 MessageHeaderAccessor accessor = MessageHeaderAccessor.getAccessor(message, MessageHeaderAccessor.class); 058 return (accessor != null ? accessor : new MessageHeaderAccessor(message)); 059 } 060 else if (MessageHeaderAccessor.class.isAssignableFrom(paramType)) { 061 MessageHeaderAccessor accessor = MessageHeaderAccessor.getAccessor(message, MessageHeaderAccessor.class); 062 if (accessor != null && paramType.isAssignableFrom(accessor.getClass())) { 063 return accessor; 064 } 065 else { 066 Method method = ReflectionUtils.findMethod(paramType, "wrap", Message.class); 067 if (method == null) { 068 throw new IllegalStateException( 069 "Cannot create accessor of type " + paramType + " for message " + message); 070 } 071 return ReflectionUtils.invokeMethod(method, null, message); 072 } 073 } 074 else { 075 throw new IllegalStateException( 076 "Unexpected method parameter type " + paramType + "in method " + parameter.getMethod() + ". " 077 + "@Headers method arguments must be assignable to java.util.Map."); 078 } 079 } 080 081}