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 */
017package org.apache.camel.processor;
018
019import org.apache.camel.AsyncCallback;
020import org.apache.camel.AsyncProcessor;
021import org.apache.camel.Exchange;
022import org.apache.camel.Expression;
023import org.apache.camel.Traceable;
024import org.apache.camel.support.ServiceSupport;
025import org.apache.camel.util.AsyncProcessorHelper;
026import org.apache.camel.util.CamelLogger;
027
028/**
029 * A processor which evaluates an {@link Expression} and logs it.
030 *
031 * @version 
032 */
033public 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}