spring-batch AmqpItemReader 源码
spring-batch AmqpItemReader 代码
文件路径：/spring-batch-infrastructure/src/main/java/org/springframework/batch/item/amqp/AmqpItemReader.java
/*
* Copyright 2012-2019 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
*
* https://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.amqp;
import org.springframework.amqp.core.AmqpTemplate;
import org.springframework.amqp.core.Message;
import org.springframework.batch.item.ItemReader;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
/**
* <p>
* AMQP {@link ItemReader} implementation using an {@link AmqpTemplate} to receive and/or
* convert messages.
* </p>
*
* @author Chris Schaefer
* @author Mahmoud Ben Hassine
*/
public class AmqpItemReader<T> implements ItemReader<T> {
private final AmqpTemplate amqpTemplate;
private Class<? extends T> itemType;
/**
* Initialize the AmqpItemReader.
* @param amqpTemplate the template to be used. Must not be null.
*/
public AmqpItemReader(final AmqpTemplate amqpTemplate) {
Assert.notNull(amqpTemplate, "AmqpTemplate must not be null");
this.amqpTemplate = amqpTemplate;
}
@Nullable
@Override
@SuppressWarnings("unchecked")
public T read() {
if (itemType != null && itemType.isAssignableFrom(Message.class)) {
return (T) amqpTemplate.receive();
}
Object result = amqpTemplate.receiveAndConvert();
if (itemType != null && result != null) {
Assert.state(itemType.isAssignableFrom(result.getClass()),
"Received message payload of wrong type: expected [" + itemType + "]");
}
return (T) result;
}
/**
* Establish the itemType for the reader.
* @param itemType class type that will be returned by the reader.
*/
public void setItemType(Class<? extends T> itemType) {
Assert.notNull(itemType, "Item type cannot be null");
this.itemType = itemType;
}
}
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