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An easy-to-use Spring bridge for MyBatis sql mapping framework.
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/**
 *    Copyright 2010-2016 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.mybatis.spring.batch;

import static org.springframework.util.Assert.isTrue;
import static org.springframework.util.Assert.notNull;

import java.util.List;

import org.apache.ibatis.executor.BatchResult;
import org.apache.ibatis.logging.Log;
import org.apache.ibatis.logging.LogFactory;
import org.apache.ibatis.session.ExecutorType;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionTemplate;
import org.springframework.batch.item.ItemWriter;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.dao.EmptyResultDataAccessException;
import org.springframework.dao.InvalidDataAccessResourceUsageException;

/**
 * {@code ItemWriter} that uses the batching features from
 * {@code SqlSessionTemplate} to execute a batch of statements for all items
 * provided.

 *
 * Provided to facilitate the migration from Spring-Batch iBATIS 2 writers to MyBatis 3

 *
 * The user must provide a MyBatis statement id that points to the SQL statement defined
 * in the MyBatis.

 *
 * It is expected that {@link #write(List)} is called inside a transaction. If it is not
 * each statement call will be autocommitted and flushStatements will return no results.

 *
 * The writer is thread safe after its properties are set (normal singleton
 * behavior), so it can be used to write in multiple concurrent transactions.
 *
 * @author Eduardo Macarron
 * 
 * @since 1.1.0
 */
public class MyBatisBatchItemWriter implements ItemWriter, InitializingBean {

  private static final Log LOGGER = LogFactory.getLog(MyBatisBatchItemWriter.class);

  private SqlSessionTemplate sqlSessionTemplate;

  private String statementId;

  private boolean assertUpdates = true;

  /**
   * Public setter for the flag that determines whether an assertion is made
   * that all items cause at least one row to be updated.
   *
   * @param assertUpdates the flag to set. Defaults to true;
   */
  public void setAssertUpdates(boolean assertUpdates) {
    this.assertUpdates = assertUpdates;
  }

  /**
   * Public setter for {@link SqlSessionFactory} for injection purposes.
   *
   * @param sqlSessionFactory a factory object for the {@link SqlSession}.
   */
  public void setSqlSessionFactory(SqlSessionFactory sqlSessionFactory) {
    if (sqlSessionTemplate == null) {
      this.sqlSessionTemplate = new SqlSessionTemplate(sqlSessionFactory, ExecutorType.BATCH);
    }
  }

  /**
   * Public setter for the {@link SqlSessionTemplate}.
   *
   * @param sqlSessionTemplate a template object for use the {@link SqlSession} on the Spring managed transaction
   */
  public void setSqlSessionTemplate(SqlSessionTemplate sqlSessionTemplate) {
    this.sqlSessionTemplate = sqlSessionTemplate;
  }

  /**
   * Public setter for the statement id identifying the statement in the SqlMap
   * configuration file.
   *
   * @param statementId the id for the statement
   */
  public void setStatementId(String statementId) {
    this.statementId = statementId;
  }

  /**
   * Check mandatory properties - there must be an SqlSession and a statementId.
   */
  @Override
  public void afterPropertiesSet() {
    notNull(sqlSessionTemplate, "A SqlSessionFactory or a SqlSessionTemplate is required.");
    isTrue(ExecutorType.BATCH == sqlSessionTemplate.getExecutorType(), "SqlSessionTemplate's executor type must be BATCH");
    notNull(statementId, "A statementId is required.");
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public void write(final List items) {

    if (!items.isEmpty()) {

      if (LOGGER.isDebugEnabled()) {
        LOGGER.debug("Executing batch with " + items.size() + " items.");
      }

      for (T item : items) {
        sqlSessionTemplate.update(statementId, item);
      }

      List results = sqlSessionTemplate.flushStatements();

      if (assertUpdates) {
        if (results.size() != 1) {
          throw new InvalidDataAccessResourceUsageException("Batch execution returned invalid results. " +
              "Expected 1 but number of BatchResult objects returned was " + results.size());
        }

        int[] updateCounts = results.get(0).getUpdateCounts();

        for (int i = 0; i < updateCounts.length; i++) {
          int value = updateCounts[i];
          if (value == 0) {
            throw new EmptyResultDataAccessException("Item " + i + " of " + updateCounts.length
                + " did not update any rows: [" + items.get(i) + "]", 1);
          }
        }
      }
    }
  }

}