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.Message;
024import org.apache.camel.Traceable;
025import org.apache.camel.impl.DefaultMessage;
026import org.apache.camel.support.ServiceSupport;
027import org.apache.camel.util.AsyncProcessorHelper;
028import org.apache.camel.util.ExchangeHelper;
029import org.apache.camel.util.ObjectHelper;
030
031/**
032 * A processor which sets the body on the OUT message with an {@link Expression}
033 */
034public class TransformProcessor extends ServiceSupport implements AsyncProcessor, Traceable {
035    private final Expression expression;
036
037    public TransformProcessor(Expression expression) {
038        ObjectHelper.notNull(expression, "expression", this);
039        this.expression = expression;
040    }
041
042    public void process(Exchange exchange) throws Exception {
043        AsyncProcessorHelper.process(this, exchange);
044    }
045
046    public boolean process(Exchange exchange, AsyncCallback callback) {
047        try {
048            Object newBody = expression.evaluate(exchange, Object.class);
049
050            if (exchange.getException() != null) {
051                // the expression threw an exception so we should break-out
052                callback.done(true);
053                return true;
054            }
055
056            boolean out = exchange.hasOut();
057            Message old = out ? exchange.getOut() : exchange.getIn();
058
059            // create a new message container so we do not drag specialized message objects along
060            // but that is only needed if the old message is a specialized message
061            boolean copyNeeded = !(old.getClass().equals(DefaultMessage.class));
062
063            if (copyNeeded) {
064                Message msg = new DefaultMessage();
065                msg.copyFrom(old);
066                msg.setBody(newBody);
067
068                // replace message on exchange (must set as OUT)
069                ExchangeHelper.replaceMessage(exchange, msg, true);
070            } else {
071                // no copy needed so set replace value directly
072                old.setBody(newBody);
073
074                // but the message must be on OUT
075                if (!exchange.hasOut()) {
076                    exchange.setOut(exchange.getIn());
077                }
078            }
079
080        } catch (Throwable e) {
081            exchange.setException(e);
082        }
083
084        callback.done(true);
085        return true;
086    }
087
088    @Override
089    public String toString() {
090        return "Transform(" + expression + ")";
091    }
092
093    public String getTraceLabel() {
094        return "transform[" + expression + "]";
095    }
096
097    @Override
098    protected void doStart() throws Exception {
099        // noop
100    }
101
102    @Override
103    protected void doStop() throws Exception {
104        // noop
105    }
106}