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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 2007-2014 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.
 *
 * For redistributing this software or a derivative work under a license other
 * than the GPL-compatible Free Software License as defined by the Free
 * Software Foundation or approved by OSI, you must first obtain a commercial
 * license to this software product from Volker Bergmann.
 *
 * 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.HeavyweightIterator;
import com.rapiddweller.common.exception.ExceptionFactory;
import org.slf4j.LoggerFactory;
import org.slf4j.Logger;

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

/**
 * Wraps a ResultSet into the semantic of a {@link HeavyweightIterator}.


 * Created: 15.08.2007 18:19:25
 * @author Volker Bergmann
 * @see HeavyweightIterator
 */
public class ResultSetIterator implements HeavyweightIterator {

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

  private final ResultSet resultSet;
  private Boolean hasNext;
  private String[] columnLabels;
  private boolean closed;
  private final String query;

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

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

  public ResultSetIterator(ResultSet resultSet, String query) {
    if (resultSet == null) {
      throw ExceptionFactory.getInstance().illegalArgument("resultSet is null");
    }
    this.resultSet = resultSet;
    this.hasNext = null;
    this.closed = false;
    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().internalError("Error querying column meta data", e);
      }
    }
    return columnLabels;
  }

  @Override
  public boolean hasNext() {
    if (logger.isDebugEnabled()) {
      logger.debug("hasNext() called on: {}", this);
    }
    if (hasNext != null) {
      return hasNext;
    }
    if (closed) {
      return false;
    }
    try {
      if (logger.isDebugEnabled()) {
        logger.debug("hasNext() checks resultSet availability of: {}", this);
      }
      hasNext = resultSet.next();
      if (!hasNext) {
        close();
      }
      return hasNext;
    } catch (SQLException e) {
      throw ExceptionFactory.getInstance().dbQueryFailed("Error in query: " + query, e);
    }
  }

  @Override
  public ResultSet next() {
    if (logger.isDebugEnabled()) {
      logger.debug("next() called on: {}", this);
    }
    if (!hasNext()) {
      throw new NoSuchElementException("No more row available. Use hasNext() for checking availability.");
    }
    hasNext = null;
    return resultSet;
  }

  @Override
  public void remove() {
    throw ExceptionFactory.getInstance().illegalOperation("Not supported");
  }

  @Override
  public synchronized void close() {
    if (closed) {
      return;
    }
    logger.debug("closing {}", this);
    hasNext = false;
    DBUtil.closeResultSetAndStatement(resultSet);
    closed = true;
  }

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

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

}