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.Iterator;
020    
021    import org.apache.camel.CamelContext;
022    import org.apache.camel.Exchange;
023    import org.apache.camel.Expression;
024    import org.apache.camel.util.ObjectHelper;
025    
026    /**
027     * Implements a <a href="http://camel.apache.org/dynamic-router.html">Dynamic Router</a> pattern
028     * where the destination(s) is computed at runtime.
029     * <p/>
030     * This implementation builds on top of {@link org.apache.camel.processor.RoutingSlip} which contains
031     * the most logic.
032     *
033     * @version 
034     */
035    public class DynamicRouter extends RoutingSlip {
036        
037        public DynamicRouter(CamelContext camelContext) {
038            super(camelContext);
039        }
040    
041        public DynamicRouter(CamelContext camelContext, Expression expression, String uriDelimiter) {
042            super(camelContext, expression, uriDelimiter);
043        }
044    
045        @Override
046        protected RoutingSlipIterator createRoutingSlipIterator(Exchange exchange) throws Exception {
047            return new DynamicRoutingSlipIterator(expression);
048        }
049    
050        /**
051         * The dynamic routing slip iterator.
052         */
053        private final class DynamicRoutingSlipIterator implements RoutingSlipIterator {
054    
055            private final Expression slip;
056            private Iterator<?> current;
057    
058            private DynamicRoutingSlipIterator(Expression slip) {
059                this.slip = slip;
060            }
061    
062            public boolean hasNext(Exchange exchange) {
063                if (current != null && current.hasNext()) {
064                    return true;
065                }
066                // evaluate next slip
067                Object routingSlip = slip.evaluate(exchange, Object.class);
068                if (routingSlip == null) {
069                    return false;
070                }
071                current = ObjectHelper.createIterator(routingSlip, uriDelimiter);
072                return current != null && current.hasNext();
073            }
074    
075            public Object next(Exchange exchange) {
076                return current.next();
077            }
078        }
079    }