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.support; 018 019import java.util.Map; 020 021import org.apache.commons.logging.Log; 022import org.apache.commons.logging.LogFactory; 023 024import org.springframework.lang.Nullable; 025import org.springframework.messaging.MessageHeaders; 026import org.springframework.util.StringUtils; 027 028/** 029 * A base {@link HeaderMapper} implementation. 030 * 031 * @author Stephane Nicoll 032 * @since 4.1 033 * @param <T> type of the instance to and from which headers will be mapped 034 */ 035public abstract class AbstractHeaderMapper<T> implements HeaderMapper<T> { 036 037 protected final Log logger = LogFactory.getLog(getClass()); 038 039 private String inboundPrefix = ""; 040 041 private String outboundPrefix = ""; 042 043 044 /** 045 * Specify a prefix to be appended to the message header name for any 046 * user-defined property that is being mapped into the MessageHeaders. 047 * The default is an empty String (no prefix). 048 */ 049 public void setInboundPrefix(@Nullable String inboundPrefix) { 050 this.inboundPrefix = (inboundPrefix != null ? inboundPrefix : ""); 051 } 052 053 /** 054 * Specify a prefix to be appended to the protocol property name for any 055 * user-defined message header that is being mapped into the protocol-specific 056 * Message. The default is an empty String (no prefix). 057 */ 058 public void setOutboundPrefix(@Nullable String outboundPrefix) { 059 this.outboundPrefix = (outboundPrefix != null ? outboundPrefix : ""); 060 } 061 062 063 /** 064 * Generate the name to use to set the header defined by the specified 065 * {@code headerName} to the protocol specific message. 066 * @see #setOutboundPrefix 067 */ 068 protected String fromHeaderName(String headerName) { 069 String propertyName = headerName; 070 if (StringUtils.hasText(this.outboundPrefix) && !propertyName.startsWith(this.outboundPrefix)) { 071 propertyName = this.outboundPrefix + headerName; 072 } 073 return propertyName; 074 } 075 076 /** 077 * Generate the name to use to set the header defined by the specified 078 * {@code propertyName} to the {@link MessageHeaders} instance. 079 * @see #setInboundPrefix(String) 080 */ 081 protected String toHeaderName(String propertyName) { 082 String headerName = propertyName; 083 if (StringUtils.hasText(this.inboundPrefix) && !headerName.startsWith(this.inboundPrefix)) { 084 headerName = this.inboundPrefix + propertyName; 085 } 086 return headerName; 087 } 088 089 /** 090 * Return the header value, or {@code null} if it does not exist 091 * or does not match the requested {@code type}. 092 */ 093 @Nullable 094 protected <V> V getHeaderIfAvailable(Map<String, Object> headers, String name, Class<V> type) { 095 Object value = headers.get(name); 096 if (value == null) { 097 return null; 098 } 099 if (!type.isAssignableFrom(value.getClass())) { 100 if (logger.isDebugEnabled()) { 101 logger.debug("Skipping header '" + name + "': expected type [" + type + "], but got [" + 102 value.getClass() + "]"); 103 } 104 return null; 105 } 106 else { 107 return type.cast(value); 108 } 109 } 110 111}