spring-batch HibernateItemWriter 源码

spring-batch HibernateItemWriter 代码

文件路径：/spring-batch-infrastructure/src/main/java/org/springframework/batch/item/database/HibernateItemWriter.java

/*
 * Copyright 2006-2021 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.database;

import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.context.spi.CurrentSessionContext;

import org.springframework.batch.item.ItemWriter;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.util.Assert;

/**
 * {@link ItemWriter} that uses a Hibernate session to save or update entities that are
 * not part of the current Hibernate session. It will also flush the session after writing
 * (i.e. at chunk boundaries if used in a Spring Batch TaskletStep). It will also clear
 * the session on write default (see {@link #setClearSession(boolean) clearSession}
 * property).<br>
 * <br>
 *
 * The writer is thread-safe once properties are set (normal singleton behavior) if a
 * {@link CurrentSessionContext} that uses only one session per thread is used.
 *
 * @author Dave Syer
 * @author Thomas Risberg
 * @author Michael Minella
 * @author Mahmoud Ben Hassine
 *
 */
public class HibernateItemWriter<T> implements ItemWriter<T>, InitializingBean {

	protected static final Log logger = LogFactory.getLog(HibernateItemWriter.class);

	private SessionFactory sessionFactory;

	private boolean clearSession = true;

	/**
	 * Flag to indicate that the session should be cleared and flushed at the end of the
	 * write (default true).
	 * @param clearSession the flag value to set
	 */
	public void setClearSession(boolean clearSession) {
		this.clearSession = clearSession;
	}

	/**
	 * Set the Hibernate SessionFactory to be used internally.
	 * @param sessionFactory session factory to be used by the writer
	 */
	public void setSessionFactory(SessionFactory sessionFactory) {
		this.sessionFactory = sessionFactory;
	}

	/**
	 * Check mandatory properties - there must be a sessionFactory.
	 */
	@Override
	public void afterPropertiesSet() {
		Assert.state(sessionFactory != null, "SessionFactory must be provided");
	}

	/**
	 * Save or update any entities not in the current hibernate session and then flush the
	 * hibernate session.
	 *
	 * @see org.springframework.batch.item.ItemWriter#write(java.util.List)
	 */
	@Override
	public void write(List<? extends T> items) {
		doWrite(sessionFactory, items);
		sessionFactory.getCurrentSession().flush();
		if (clearSession) {
			sessionFactory.getCurrentSession().clear();
		}
	}

	/**
	 * Do perform the actual write operation using Hibernate's API. This can be overridden
	 * in a subclass if necessary.
	 * @param sessionFactory Hibernate SessionFactory to be used
	 * @param items the list of items to use for the write
	 */
	protected void doWrite(SessionFactory sessionFactory, List<? extends T> items) {
		if (logger.isDebugEnabled()) {
			logger.debug("Writing to Hibernate with " + items.size() + " items.");
		}

		Session currentSession = sessionFactory.getCurrentSession();

		if (!items.isEmpty()) {
			long saveOrUpdateCount = 0;
			for (T item : items) {
				if (!currentSession.contains(item)) {
					currentSession.saveOrUpdate(item);
					saveOrUpdateCount++;
				}
			}
			if (logger.isDebugEnabled()) {
				logger.debug(saveOrUpdateCount + " entities saved/updated.");
				logger.debug((items.size() - saveOrUpdateCount) + " entities found in session.");
			}
		}
	}

}

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