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• ResultSetDataIterator.java

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com.rapiddweller.jdbacl.ResultSetDataIterator Maven / Gradle / Ivy

/*
 * (c) Copyright 2011-2014 by Volker Bergmann. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, is permitted under the terms of the
 * GNU General Public License (GPL).
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * WITHOUT A WARRANTY OF ANY KIND. ALL EXPRESS OR IMPLIED CONDITIONS,
 * REPRESENTATIONS AND WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE
 * HEREBY EXCLUDED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

package com.rapiddweller.jdbacl;

import com.rapiddweller.common.IOUtil;
import com.rapiddweller.common.StringUtil;
import com.rapiddweller.format.DataContainer;
import com.rapiddweller.format.DataIterator;
import org.slf4j.LoggerFactory;
import org.slf4j.Logger;

import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;

/**
 * Provides {@link DataIterator}-style access to a {@link ResultSet}.


 * Created: 03.08.2011 19:24:35
 *
 * @author Volker Bergmann
 * @since 0.6.10
 */
public class ResultSetDataIterator implements DataIterator {

  private ResultSet resultSet;
  private String[] columnLabels;

  private final String query;

  // constructors ----------------------------------------------------------------------------------------------------

  /**
   * Instantiates a new Result set data iterator.
   *
   * @param resultSet the result set
   */
  public ResultSetDataIterator(ResultSet resultSet) {
    this(resultSet, "");
  }

  /**
   * Instantiates a new Result set data iterator.
   *
   * @param resultSet the result set
   * @param query     the query
   */
  public ResultSetDataIterator(ResultSet resultSet, String query) {
    if (resultSet == null) {
      throw new IllegalArgumentException("resultSet is null");
    }
    this.resultSet = resultSet;
    if (StringUtil.isEmpty(query)) {
      throw new IllegalArgumentException("query is empty");
    }
    this.query = query;
  }

  // interface -------------------------------------------------------------------------------------------------------

  /**
   * Get column labels string [ ].
   *
   * @return the string [ ]
   */
  public String[] getColumnLabels() {
    if (columnLabels == null) {
      try {
        ResultSetMetaData metaData = resultSet.getMetaData();
        int n = metaData.getColumnCount();
        columnLabels = new String[n];
        for (int i = 0; i < n; i++) {
          columnLabels[i] = metaData.getColumnLabel(i + 1);
        }
      } catch (SQLException e) {
        throw new RuntimeException("Error querying column meta data", e);
      }
    }
    return columnLabels;
  }

  @Override
  public Class getType() {
    return ResultSet.class;
  }

  @Override
  public DataContainer next(DataContainer container) {
    LOGGER.debug("next() called on {}", this);
    if (resultSet == null) {
      return null;
    }
    try {
      if (resultSet.next()) {
        return container.setData(resultSet);
      } else {
        IOUtil.close(this);
        return null;
      }
    } catch (SQLException e) {
      throw new RuntimeException(e);
    }
  }

  @Override
  public synchronized void close() {
    LOGGER.debug("closing {}", this);
    if (resultSet == null) {
      return;
    }
    DBUtil.closeResultSetAndStatement(resultSet);
    resultSet = null;
  }

  // java.lang.Object overrides --------------------------------------------------------------------------------------

  @Override
  public String toString() {
    return getClass().getSimpleName() + '[' + query + ']';
  }

  private static final Logger LOGGER = LoggerFactory.getLogger(ResultSetIterator.class);

}