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 java.util.ArrayList;
020    import java.util.List;
021    
022    import org.apache.camel.Exchange;
023    import org.apache.camel.Predicate;
024    import org.apache.camel.Processor;
025    import org.apache.camel.impl.ServiceSupport;
026    import org.apache.camel.util.ServiceHelper;
027    
028    /**
029     * Implements a Choice structure where one or more predicates are used which if
030     * they are true their processors are used, with a default otherwise clause used
031     * if none match.
032     * 
033     * @version $Revision: 792 $
034     */
035    public class ChoiceProcessor extends ServiceSupport implements Processor {
036        private List<FilterProcessor> filters = new ArrayList<FilterProcessor>();
037        private Processor otherwise;
038    
039        public ChoiceProcessor(List<FilterProcessor> filters, Processor otherwise) {
040            this.filters = filters;
041            this.otherwise = otherwise;
042        }
043    
044        public void process(Exchange exchange) throws Exception {
045            for (FilterProcessor filterProcessor : filters) {
046                Predicate<Exchange> predicate = filterProcessor.getPredicate();
047                if (predicate != null && predicate.matches(exchange)) {
048                    // process next will also take care (has not null test) if next was a stop().
049                    // stop() has no processor to execute, and thus we will end in a NPE 
050                    filterProcessor.processNext(exchange);
051                    return;
052                }
053            }
054            if (otherwise != null) {
055                otherwise.process(exchange);
056            }
057        }
058    
059        @Override
060        public String toString() {
061            StringBuilder builder = new StringBuilder("choice{");
062            boolean first = true;
063            for (FilterProcessor processor : filters) {
064                if (first) {
065                    first = false;
066                } else {
067                    builder.append(", ");
068                }
069                builder.append("when ");
070                builder.append(processor.getPredicate().toString());
071                builder.append(": ");
072                builder.append(processor.getProcessor());
073            }
074            if (otherwise != null) {
075                builder.append(", otherwise: ");
076                builder.append(otherwise);
077            }
078            builder.append("}");
079            return builder.toString();
080        }
081    
082        public List<FilterProcessor> getFilters() {
083            return filters;
084        }
085    
086        public Processor getOtherwise() {
087            return otherwise;
088        }
089    
090        protected void doStart() throws Exception {
091            ServiceHelper.startServices(filters);
092            ServiceHelper.startServices(otherwise);
093        }
094    
095        protected void doStop() throws Exception {
096            ServiceHelper.stopServices(otherwise);
097            ServiceHelper.stopServices(filters);
098        }
099    }