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