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'jdbacl' stands for 'Java DataBase ACcess Layer' and provides utilities for accessing JDBC databases from Java programs, retrieving meta information in an object model and querying database data. 'rapiddweller jdbacl' is forked from Databene jdbacl by Volker Bergmann.

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/*
 * (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.common.exception.ExceptionFactory;
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 static final Logger logger = LoggerFactory.getLogger(ResultSetDataIterator.class);

  private ResultSet resultSet;
  private String[] columnLabels;

  private final String query;

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

  public ResultSetDataIterator(ResultSet resultSet) {
    this(resultSet, "");
  }

  public ResultSetDataIterator(ResultSet resultSet, String query) {
    logger.debug("Instantiating {} for query {}", getClass(), query);
    if (resultSet == null) {
      throw ExceptionFactory.getInstance().illegalArgument("resultSet is null");
    }
    this.resultSet = resultSet;
    if (StringUtil.isEmpty(query)) {
      throw ExceptionFactory.getInstance().illegalArgument("query is empty");
    }
    this.query = query;
  }

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

  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 ExceptionFactory.getInstance().dbQueryFailed("Error querying column meta data", e);
      }
    }
    return columnLabels;
  }

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

  @Override
  public synchronized DataContainer next(DataContainer container) {
    logger.debug("next() called on {}", this);
    if (resultSet == null) {
      return null;
    }
    try {
      // make sure resultSet is still open
      if (!resultSet.isClosed() && resultSet.next()) {
        return container.setData(resultSet);
      } else {
        resultSet.close();
        IOUtil.close(this);
        return null;
      }
    } catch (SQLException e) {
      throw ExceptionFactory.getInstance().dbQueryFailed("ResultSet iteration failed", 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 + ']';
  }

}