001/* 002 * Copyright 2012-2018 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.amqp; 018 019import org.springframework.amqp.core.AmqpTemplate; 020import org.springframework.amqp.core.Message; 021import org.springframework.batch.item.ItemReader; 022import org.springframework.util.Assert; 023 024/** 025 * <p> 026 * AMQP {@link ItemReader} implementation using an {@link AmqpTemplate} to 027 * receive and/or convert messages. 028 * </p> 029 * 030 * @author Chris Schaefer 031 * @author Mahmoud Ben Hassine 032 */ 033public class AmqpItemReader<T> implements ItemReader<T> { 034 private final AmqpTemplate amqpTemplate; 035 private Class<? extends T> itemType; 036 037 /** 038 * Initialize the AmqpItemReader. 039 * 040 * @param amqpTemplate the template to be used. Must not be null. 041 */ 042 public AmqpItemReader(final AmqpTemplate amqpTemplate) { 043 Assert.notNull(amqpTemplate, "AmqpTemplate must not be null"); 044 045 this.amqpTemplate = amqpTemplate; 046 } 047 048 @Override 049 @SuppressWarnings("unchecked") 050 public T read() { 051 if (itemType != null && itemType.isAssignableFrom(Message.class)) { 052 return (T) amqpTemplate.receive(); 053 } 054 055 Object result = amqpTemplate.receiveAndConvert(); 056 057 if (itemType != null && result != null) { 058 Assert.state(itemType.isAssignableFrom(result.getClass()), 059 "Received message payload of wrong type: expected [" + itemType + "]"); 060 } 061 062 return (T) result; 063 } 064 065 /** 066 * Establish the itemType for the reader. 067 * 068 * @param itemType class type that will be returned by the reader. 069 */ 070 public void setItemType(Class<? extends T> itemType) { 071 Assert.notNull(itemType, "Item type cannot be null"); 072 this.itemType = itemType; 073 } 074}