001    /**
002     *
003     * Licensed to the Apache Software Foundation (ASF) under one or more
004     * contributor license agreements.  See the NOTICE file distributed with
005     * this work for additional information regarding copyright ownership.
006     * The ASF licenses this file to You under the Apache License, Version 2.0
007     * (the "License"); you may not use this file except in compliance with
008     * the License.  You may obtain a copy of the License at
009     *
010     * http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    package org.apache.camel.impl;
019    
020    import org.apache.camel.Message;
021    
022    import java.util.HashMap;
023    import java.util.Map;
024    
025    /**
026     * The default implementation of {@link Message}
027     *
028     * @version $Revision: 540969 $
029     */
030    public class DefaultMessage extends MessageSupport {
031        private Map<String, Object> headers;
032    
033        @Override
034        public String toString() {
035            return "Message: " + getBody();
036        }
037    
038        public Object getHeader(String name) {
039            return getHeaders().get(name);
040        }
041    
042        public <T> T getHeader(String name, Class<T> type) {
043            Object value = getHeader(name);
044            return getExchange().getContext().getTypeConverter().convertTo(type, value);
045        }
046    
047        public void setHeader(String name, Object value) {
048            if (headers == null) {
049                headers = createHeaders();
050            }
051            headers.put(name, value);
052        }
053    
054        public Map<String, Object> getHeaders() {
055            if (headers == null) {
056                headers = createHeaders();
057            }
058            return headers;
059        }
060    
061        public void setHeaders(Map<String, Object> headers) {
062            this.headers = headers;
063        }
064    
065        public DefaultMessage newInstance() {
066            return new DefaultMessage();
067        }
068    
069        /**
070         * A factory method to lazily create the headers to make it easy to create efficient Message implementations
071         * which only construct and populate the Map on demand
072         *
073         * @return return a newly constructed Map possibly containing headers from the underlying inbound transport
074         */
075        protected Map<String, Object> createHeaders() {
076            HashMap<String, Object> map = new HashMap<String, Object>();
077            populateInitialHeaders(map);
078            return map;
079        }
080    
081        /**
082         * A strategy method populate the initial set of headers on an inbound message from an underlying binding
083         *
084         * @param map is the empty header map to populate
085         */
086        protected void populateInitialHeaders(Map<String, Object> map) {
087        }
088    }