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.support.ServiceSupport;
026import org.apache.camel.util.AsyncProcessorHelper;
027
028/**
029 * A processor which sets the header on the IN or OUT message with an {@link org.apache.camel.Expression}
030 */
031public class SetHeaderProcessor extends ServiceSupport implements AsyncProcessor, Traceable {
032    private final String headerName;
033    private final Expression expression;
034
035    public SetHeaderProcessor(String headerName, Expression expression) {
036        this.headerName = headerName;
037        this.expression = expression;
038    }
039
040    public void process(Exchange exchange) throws Exception {
041        AsyncProcessorHelper.process(this, exchange);
042    }
043
044    @Override
045    public boolean process(Exchange exchange, AsyncCallback callback) {
046        try {
047            Object newHeader = expression.evaluate(exchange, Object.class);
048
049            if (exchange.getException() != null) {
050                // the expression threw an exception so we should break-out
051                callback.done(true);
052                return true;
053            }
054
055            boolean out = exchange.hasOut();
056            Message old = out ? exchange.getOut() : exchange.getIn();
057
058            old.setHeader(headerName, newHeader);
059
060        } catch (Throwable e) {
061            exchange.setException(e);
062        }
063
064        callback.done(true);
065        return true;
066    }
067
068    @Override
069    public String toString() {
070        return "SetHeader(" + headerName + ", " + expression + ")";
071    }
072
073    public String getTraceLabel() {
074        return "setHeader[" + headerName + ", " + expression + "]";
075    }
076
077    @Override
078    protected void doStart() throws Exception {
079        // noop
080    }
081
082    @Override
083    protected void doStop() throws Exception {
084        // noop
085    }
086}