001/* 002 * Copyright 2006-2007 the original author or authors. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * https://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package org.springframework.batch.item.jms; 018 019import org.apache.commons.logging.Log; 020import org.apache.commons.logging.LogFactory; 021import org.springframework.batch.item.ItemReader; 022import org.springframework.beans.factory.InitializingBean; 023import org.springframework.jms.core.JmsOperations; 024import org.springframework.jms.core.JmsTemplate; 025import org.springframework.util.Assert; 026 027import javax.jms.Message; 028 029/** 030 * An {@link ItemReader} for JMS using a {@link JmsTemplate}. The template 031 * should have a default destination, which will be used to provide items in 032 * {@link #read()}.<br> 033 * <br> 034 * 035 * The implementation is thread-safe after its properties are set (normal 036 * singleton behavior). 037 * 038 * @author Dave Syer 039 * 040 */ 041public class JmsItemReader<T> implements ItemReader<T>, InitializingBean { 042 043 protected Log logger = LogFactory.getLog(getClass()); 044 045 protected Class<? extends T> itemType; 046 047 protected JmsOperations jmsTemplate; 048 049 /** 050 * Setter for JMS template. 051 * 052 * @param jmsTemplate a {@link JmsOperations} instance 053 */ 054 public void setJmsTemplate(JmsOperations jmsTemplate) { 055 this.jmsTemplate = jmsTemplate; 056 if (jmsTemplate instanceof JmsTemplate) { 057 JmsTemplate template = (JmsTemplate) jmsTemplate; 058 Assert.isTrue(template.getReceiveTimeout() != JmsTemplate.RECEIVE_TIMEOUT_INDEFINITE_WAIT, 059 "JmsTemplate must have a receive timeout!"); 060 Assert.isTrue(template.getDefaultDestination() != null || template.getDefaultDestinationName() != null, 061 "JmsTemplate must have a defaultDestination or defaultDestinationName!"); 062 } 063 } 064 065 /** 066 * Set the expected type of incoming message payloads. Set this to 067 * {@link Message} to receive the raw underlying message. 068 * 069 * @param itemType the java class of the items to be delivered. Typically 070 * the same as the class parameter 071 * 072 * @throws IllegalStateException if the message payload is of the wrong 073 * type. 074 */ 075 public void setItemType(Class<? extends T> itemType) { 076 this.itemType = itemType; 077 } 078 079 @Override 080 @SuppressWarnings("unchecked") 081 public T read() { 082 if (itemType != null && itemType.isAssignableFrom(Message.class)) { 083 return (T) jmsTemplate.receive(); 084 } 085 Object result = jmsTemplate.receiveAndConvert(); 086 if (itemType != null && result != null) { 087 Assert.state(itemType.isAssignableFrom(result.getClass()), 088 "Received message payload of wrong type: expected [" + itemType + "]"); 089 } 090 return (T) result; 091 } 092 093 @Override 094 public void afterPropertiesSet() throws Exception { 095 Assert.notNull(this.jmsTemplate, "The 'jmsTemplate' is required."); 096 } 097}