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.AsyncCallback;
020    import org.apache.camel.AsyncProcessor;
021    import org.apache.camel.Exchange;
022    import org.apache.camel.Expression;
023    import org.apache.camel.Traceable;
024    import org.apache.camel.support.ServiceSupport;
025    import org.apache.camel.util.AsyncProcessorHelper;
026    import org.apache.camel.util.CamelLogger;
027    
028    /**
029     * A processor which evaluates an {@link Expression} and logs it.
030     *
031     * @version 
032     */
033    public class LogProcessor extends ServiceSupport implements AsyncProcessor, Traceable {
034    
035        private final Expression expression;
036        private final CamelLogger logger;
037    
038        public LogProcessor(Expression expression, CamelLogger logger) {
039            this.expression = expression;
040            this.logger = logger;
041        }
042    
043        public void process(Exchange exchange) throws Exception {
044            AsyncProcessorHelper.process(this, exchange);
045        }
046    
047        @Override
048        public boolean process(Exchange exchange, AsyncCallback callback) {
049            try {
050                if (logger.shouldLog()) {
051                    String msg = expression.evaluate(exchange, String.class);
052                    logger.doLog(msg);
053                }
054            } catch (Exception e) {
055                exchange.setException(e);
056            } finally {
057                // callback must be invoked
058                callback.done(true);
059            }
060            return true;
061        }
062    
063        @Override
064        public String toString() {
065            return "Log(" + logger.getLog().getName() + ")[" + expression + "]";
066        }
067    
068        public String getTraceLabel() {
069            return "log[" + expression + "]";
070        }
071    
072        @Override
073        protected void doStart() throws Exception {
074            // noop
075        }
076    
077        @Override
078        protected void doStop() throws Exception {
079            // noop
080        }
081    }