001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.camel.impl;
018    
019    import java.util.HashMap;
020    import java.util.Map;
021    
022    /**
023     * The default implementation of {@link Message}
024     * 
025     * @version $Revision: 563607 $
026     */
027    public class DefaultMessage extends MessageSupport {
028        private Map<String, Object> headers;
029    
030        @Override
031        public String toString() {
032            return "Message: " + getBody();
033        }
034    
035        public Object getHeader(String name) {
036            return getHeaders().get(name);
037        }
038    
039        public <T> T getHeader(String name, Class<T> type) {
040            Object value = getHeader(name);
041            return getExchange().getContext().getTypeConverter().convertTo(type, value);
042        }
043    
044        public void setHeader(String name, Object value) {
045            if (headers == null) {
046                headers = createHeaders();
047            }
048            headers.put(name, value);
049        }
050    
051        public Map<String, Object> getHeaders() {
052            if (headers == null) {
053                headers = createHeaders();
054            }
055            return headers;
056        }
057    
058        public void setHeaders(Map<String, Object> headers) {
059            this.headers = headers;
060        }
061    
062        public DefaultMessage newInstance() {
063            return new DefaultMessage();
064        }
065    
066        /**
067         * A factory method to lazily create the headers to make it easy to create
068         * efficient Message implementations which only construct and populate the
069         * Map on demand
070         * 
071         * @return return a newly constructed Map possibly containing headers from
072         *         the underlying inbound transport
073         */
074        protected Map<String, Object> createHeaders() {
075            HashMap<String, Object> map = new HashMap<String, Object>();
076            populateInitialHeaders(map);
077            return map;
078        }
079    
080        /**
081         * A strategy method populate the initial set of headers on an inbound
082         * 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    }