org.springframework.batch.item.jms.JmsItemReader.java Source code

Introduction

Here is the source code for org.springframework.batch.item.jms.JmsItemReader.java

Source

/*
 * Copyright 2006-2007 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.batch.item.jms;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.batch.item.ItemReader;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.jms.core.JmsOperations;
import org.springframework.jms.core.JmsTemplate;
import org.springframework.util.Assert;

import javax.jms.Message;

/**
 * An {@link ItemReader} for JMS using a {@link JmsTemplate}. The template
 * should have a default destination, which will be used to provide items in
 * {@link #read()}.<br>
 * <br>
 * 
 * The implementation is thread-safe after its properties are set (normal
 * singleton behavior).
 * 
 * @author Dave Syer
 * 
 */
public class JmsItemReader<T> implements ItemReader<T>, InitializingBean {

    protected Log logger = LogFactory.getLog(getClass());

    protected Class<? extends T> itemType;

    protected JmsOperations jmsTemplate;

    /**
     * Setter for JMS template.
     * 
     * @param jmsTemplate a {@link JmsOperations} instance
     */
    public void setJmsTemplate(JmsOperations jmsTemplate) {
        this.jmsTemplate = jmsTemplate;
        if (jmsTemplate instanceof JmsTemplate) {
            JmsTemplate template = (JmsTemplate) jmsTemplate;
            Assert.isTrue(template.getReceiveTimeout() != JmsTemplate.RECEIVE_TIMEOUT_INDEFINITE_WAIT,
                    "JmsTemplate must have a receive timeout!");
            Assert.isTrue(template.getDefaultDestination() != null || template.getDefaultDestinationName() != null,
                    "JmsTemplate must have a defaultDestination or defaultDestinationName!");
        }
    }

    /**
     * Set the expected type of incoming message payloads. Set this to
     * {@link Message} to receive the raw underlying message.
     * 
     * @param itemType the java class of the items to be delivered. Typically
     * the same as the class parameter
     * 
     * @throws IllegalStateException if the message payload is of the wrong
     * type.
     */
    public void setItemType(Class<? extends T> itemType) {
        this.itemType = itemType;
    }

    @Override
    @SuppressWarnings("unchecked")
    public T read() {
        if (itemType != null && itemType.isAssignableFrom(Message.class)) {
            return (T) jmsTemplate.receive();
        }
        Object result = jmsTemplate.receiveAndConvert();
        if (itemType != null && result != null) {
            Assert.state(itemType.isAssignableFrom(result.getClass()),
                    "Received message payload of wrong type: expected [" + itemType + "]");
        }
        return (T) result;
    }

    @Override
    public void afterPropertiesSet() throws Exception {
        Assert.notNull(this.jmsTemplate, "The 'jmsTemplate' is required.");
    }
}