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.ArrayBlockingQueue; 020 import java.util.concurrent.BlockingQueue; 021 import java.util.concurrent.TimeUnit; 022 023 import org.apache.camel.Consumer; 024 import org.apache.camel.Endpoint; 025 import org.apache.camel.Exchange; 026 import org.apache.camel.Processor; 027 import org.apache.camel.processor.Logger; 028 import org.apache.camel.spi.ExceptionHandler; 029 import org.apache.commons.logging.Log; 030 import org.apache.commons.logging.LogFactory; 031 032 /** 033 * A default implementation of the {@link PollingConsumer} which uses the normal 034 * asynchronous consumer mechanism along with a {@link BlockingQueue} to allow 035 * the caller to pull messages on demand. 036 * 037 * @version $Revision: 1.1 $ 038 */ 039 public class DefaultPollingConsumer<E extends Exchange> extends PollingConsumerSupport<E> implements 040 Processor { 041 private static final transient Log LOG = LogFactory.getLog(DefaultPollingConsumer.class); 042 private BlockingQueue<E> queue; 043 private ExceptionHandler interuptedExceptionHandler = new LoggingExceptionHandler(new Logger(LOG)); 044 private Consumer<E> consumer; 045 046 public DefaultPollingConsumer(Endpoint<E> endpoint) { 047 this(endpoint, new ArrayBlockingQueue<E>(1000)); 048 } 049 050 public DefaultPollingConsumer(Endpoint<E> endpoint, BlockingQueue<E> queue) { 051 super(endpoint); 052 this.queue = queue; 053 } 054 055 public E receiveNoWait() { 056 return receive(0); 057 } 058 059 public E receive() { 060 while (!isStopping() && !isStopped()) { 061 try { 062 return queue.take(); 063 } catch (InterruptedException e) { 064 handleInteruptedException(e); 065 } 066 } 067 return null; 068 } 069 070 public E receive(long timeout) { 071 try { 072 return queue.poll(timeout, TimeUnit.MILLISECONDS); 073 } catch (InterruptedException e) { 074 handleInteruptedException(e); 075 return null; 076 } 077 } 078 079 public void process(Exchange exchange) throws Exception { 080 queue.offer((E)exchange); 081 } 082 083 public ExceptionHandler getInteruptedExceptionHandler() { 084 return interuptedExceptionHandler; 085 } 086 087 public void setInteruptedExceptionHandler(ExceptionHandler interuptedExceptionHandler) { 088 this.interuptedExceptionHandler = interuptedExceptionHandler; 089 } 090 091 protected void handleInteruptedException(InterruptedException e) { 092 getInteruptedExceptionHandler().handleException(e); 093 } 094 095 protected void doStart() throws Exception { 096 // lets add ourselves as a consumer 097 consumer = getEndpoint().createConsumer(this); 098 consumer.start(); 099 } 100 101 protected void doStop() throws Exception { 102 if (consumer != null) { 103 try { 104 consumer.stop(); 105 } finally { 106 consumer = null; 107 } 108 } 109 } 110 }