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.impl;
018    
019    import java.util.concurrent.ScheduledExecutorService;
020    
021    import org.apache.camel.Consumer;
022    import org.apache.camel.Endpoint;
023    import org.apache.camel.Exchange;
024    import org.apache.camel.Message;
025    import org.apache.camel.PollingConsumer;
026    import org.apache.camel.Processor;
027    
028    /**
029     * A default implementation of an event driven {@link Consumer} which uses the {@link PollingConsumer}
030     *
031     * @version $Revision: 382 $
032     */
033    public class DefaultScheduledPollConsumer<E extends Exchange> extends ScheduledPollConsumer<E> {
034        private PollingConsumer<E> pollingConsumer;
035    
036        public DefaultScheduledPollConsumer(DefaultEndpoint<E> defaultEndpoint, Processor processor) {
037            super(defaultEndpoint, processor);
038        }
039    
040        public DefaultScheduledPollConsumer(Endpoint<E> endpoint, Processor processor, ScheduledExecutorService executor) {
041            super(endpoint, processor, executor);
042        }
043    
044        protected void poll() throws Exception {
045            while (true) {
046                E exchange = pollingConsumer.receiveNoWait();
047                if (exchange == null) {
048                    break;
049                }
050    
051                // if the result of the polled exchange has output we should create a new exchange and
052                // use the output as input to the next processor
053                Message out = exchange.getOut(false);
054                if (out != null) {
055                    // lets create a new exchange
056                    E newExchange = getEndpoint().createExchange();
057                    newExchange.getIn().copyFrom(out);
058                    exchange = newExchange;
059                }
060                getProcessor().process(exchange);
061            }
062        }
063    
064        @Override
065        protected void doStart() throws Exception {
066            pollingConsumer = getEndpoint().createPollingConsumer();
067            super.doStart();
068        }
069    
070        @Override
071        protected void doStop() throws Exception {
072            super.doStop();
073            if (pollingConsumer != null) {
074                pollingConsumer.stop();
075            }
076        }
077    }