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.processor;
018    
019    import org.apache.camel.Exchange;
020    import org.apache.camel.Expression;
021    import org.apache.camel.Processor;
022    import org.apache.commons.logging.Log;
023    import org.apache.commons.logging.LogFactory;
024    
025    /**
026     * A processor which sets the header on the IN message
027     */
028    public class SetHeaderProcessor extends DelegateProcessor implements Processor {
029        private static final transient Log LOG = LogFactory.getLog(SetHeaderProcessor.class);
030        private String name;
031        private Expression expression;
032    
033        public SetHeaderProcessor(String name, Expression expression) {
034            this.name = name;
035            this.expression = expression;
036        }
037    
038        public SetHeaderProcessor(String name, Expression expression,
039                Processor childProcessor) {
040            super(childProcessor);
041            this.name = name;
042            this.expression = expression;
043        }
044    
045        public void process(Exchange exchange) throws Exception {
046            Object value = expression.evaluate(exchange);
047            if (value == null) {
048                LOG.warn("Expression: " + expression
049                        + " on exchange: " + exchange + " evaluated to null.");
050            }
051            exchange.getIn().setHeader(name, value);
052            super.process(exchange);
053        }
054    
055        @Override
056        public String toString() {
057            return "setHeader(" + name + ", " + expression + ")";
058        }
059    }