org.springframework.batch.item.support.SynchronizedItemStreamReader Maven / Gradle / Ivy
/*
* Copyright 2015 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.support;
import org.springframework.batch.item.ExecutionContext;
import org.springframework.batch.item.ItemStreamReader;
import org.springframework.batch.item.NonTransientResourceException;
import org.springframework.batch.item.ParseException;
import org.springframework.batch.item.UnexpectedInputException;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.util.Assert;
/**
*
* This is a simple ItemStreamReader decorator with a synchronized ItemReader.read()
* method - which makes a non-thread-safe ItemReader thread-safe.
*
* However, if reprocessing an item is problematic then using this will make a job not
* restartable.
*
* Here are some links about the motivation behind this class:
* - https://projects.spring.io/spring-batch/faq.html#threading-reader}
* - https://stackoverflow.com/a/20002493/2910265}
*
* @author Matthew Ouyang
* @since 3.0.4
*
* @param type of object being read
*/
public class SynchronizedItemStreamReader implements ItemStreamReader, InitializingBean {
private ItemStreamReader delegate;
public void setDelegate(ItemStreamReader delegate) {
this.delegate = delegate;
}
/**
* This delegates to the read method of the delegate
*/
public synchronized T read() throws Exception, UnexpectedInputException, ParseException, NonTransientResourceException {
return this.delegate.read();
}
public void close() {
this.delegate.close();
}
public void open(ExecutionContext executionContext) {
this.delegate.open(executionContext);
}
public void update(ExecutionContext executionContext) {
this.delegate.update(executionContext);
}
@Override
public void afterPropertiesSet() throws Exception {
Assert.notNull(this.delegate, "A delegate item reader is required");
}
}