stringorder.java

来自「RESIN 3.2 最新源码」· Java 代码 · 共 70 行

/*
 * Copyright (c) 1998-2008 Caucho Technology -- all rights reserved
 *
 * This file is part of Resin(R) Open Source
 *
 * Each copy or derived work must preserve the copyright notice and this
 * notice unmodified.
 *
 * Resin Open Source is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * Resin Open Source is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
 * of NON-INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Resin Open Source; if not, write to the
 *   Free SoftwareFoundation, Inc.
 *   59 Temple Place, Suite 330
 *   Boston, MA 02111-1307  USA
 *
 * @author Scott Ferguson
 */

package com.caucho.db.sql;

import java.sql.SQLException;

/**
 * Ordering a string-valued field.
 */
class StringOrder extends Order {
  private int _column;
  
  StringOrder(int column)
  {
    _column = column;
  }

  public int compare(SelectResult result, int indexA, int indexB)
    throws SQLException
  {
    result.setRow(indexA);

    String valueA = result.getString(_column);
    
    result.setRow(indexB);
    String valueB = result.getString(_column);

    int sign = isAscending() ? 1 : -1;

    if (valueA == valueB)
      return _next == null ? 0 : _next.compare(result, indexA, indexB);
    else if (valueA == null)
      return sign;
    else if (valueB == null)
      return -sign;

    int cmp = valueA.compareTo(valueB);
    if (cmp == 0)
      return _next == null ? 0 : _next.compare(result, indexA, indexB);
    else
      return cmp;
  }
}