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.util.AsyncProcessorHelper;
025    
026    /**
027     * A {@link org.apache.camel.Processor} which evaluates an {@link Expression}
028     * and stores the result as a property on the {@link Exchange} with the key
029     * {@link Exchange#EVALUATE_EXPRESSION_RESULT}.
030     * <p/>
031     * This processor will in case of evaluation exceptions, set the caused exception
032     * on the {@link Exchange}.
033     */
034    public class EvaluateExpressionProcessor implements AsyncProcessor, Traceable {
035    
036        private final Expression expression;
037    
038        public EvaluateExpressionProcessor(Expression expression) {
039            this.expression = expression;
040        }
041    
042        @Override
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                Object result = expression.evaluate(exchange, Object.class);
051                exchange.setProperty(Exchange.EVALUATE_EXPRESSION_RESULT, result);
052            } catch (Throwable e) {
053                exchange.setException(e);
054            } finally {
055                callback.done(true);
056            }
057            return true;
058        }
059    
060        @Override
061        public String toString() {
062            return "EvalExpression[" + expression + "]";
063        }
064    
065        public String getTraceLabel() {
066            return "eval[" + expression + "]";
067        }
068    
069    }