doublecolumnspec.java

把java对象映射成数据库表中的一条记录

/*
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (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.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
 * License for the specific language governing rights and limitations under
 * the License.
 *
 * The Original Code is jRelationalFramework.
 *
 * The Initial Developer of the Original Code is is.com.
 * Portions created by is.com are Copyright (C) 2000 is.com.
 * All Rights Reserved.
 *
 * Contributor(s): Alix Jermyn ([e-mail])
 * Contributor(s): ____________________________________
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License (the "GPL") or the GNU Lesser General
 * Public license (the "LGPL"), in which case the provisions of the GPL or
 * LGPL are applicable instead of those above.  If you wish to allow use of
 * your version of this file only under the terms of either the GPL or LGPL
 * and not to allow others to use your version of this file under the MPL,
 * indicate your decision by deleting the provisions above and replace them
 * with the notice and other provisions required by either the GPL or LGPL
 * License.  If you do not delete the provisions above, a recipient may use
 * your version of this file under either the MPL or GPL or LGPL License.
 *
 */
package com.is.jrf;


import com.is.util.sql.JDBCHelper;

import java.sql.SQLException;


/**
 * This subclass of AbstractColumnSpec does Double-specific things.
 */
public class DoubleColumnSpec
    extends AbstractColumnSpec
  {


  /* ===============  Static Variables  =============== */

  protected static final Class s_class = Double.class;


  /* ===============  Constructors  =============== */

  public DoubleColumnSpec(
      String  columnName,
      String  getter,
      String  setter,
      Object  defaultValue)
    {
    super(columnName,
          getter,
          setter,
          (Double) defaultValue);
    }

  public DoubleColumnSpec(
      String  columnName,
      String  getter,
      String  setter,
      Object  defaultValue,
      int     option1)
    {
    super(columnName,
          getter,
          setter,
          (Double) defaultValue,
          option1);
    }

  public DoubleColumnSpec(
      String  columnName,
      String  getter,
      String  setter,
      Object  defaultValue,
      int     option1,
      int     option2)
    {
    super(columnName,
          getter,
          setter,
          (Double) defaultValue,
          option1,
          option2);
    }

  public DoubleColumnSpec(
      String  columnName,
      String  getter,
      String  setter,
      Object  defaultValue,
      int     option1,
      int     option2,
      int     option3)
    {
    super(columnName,
          getter,
          setter,
          (Double) defaultValue,
          option1,
          option2,
          option3);
    }


  /**
   * This method overrides the superclass implementation.
   *
   * @param obj a value of type 'Object'
   * @param dbPolicy a value of type 'DatabasePolicy'
   * @return a value of type 'String'
   */
  public String formatForSql(Object obj, DatabasePolicy dbPolicy)
    {
    Double aDouble = (Double) obj; // force a runtime error if not an Double
    return (aDouble == null ? "null" : aDouble.toString());
    } // formatForSql(...)


  public Class getColumnClass()
    {
    return s_class;
    }


  /**
   * This ensures that we get a Double from the JDBC driver.
   *
   * @param helper a value of type 'JDBCHelper'
   * @return a value of type 'Object'
   * @exception SQLException if an error occurs
   */
  public Object getColumnValueFrom(JDBCHelper helper)
          throws SQLException
    {
    return helper.getDouble(this.getColumnName());
    }


  /**
   * This method goes with encode().  The String parameter must have been
   * created by the encode() method.
   *
   * @param aString a value of type 'String'
   * @param aPO a value of type 'PersistentObject'
   */
  public Object decode(String aString)
    {
    Double returnValue = null;
    if (aString.trim().equals("null"))
        {
        return null;
        }
    try
        {
        returnValue = Double.valueOf(aString);
        }
    catch (NumberFormatException e)
        {
        throw new DatabaseException(
            "Invalid parameter to DoubleColumnSpec.getValueFrom(aString))");
        }
    return returnValue;
    }


  /**
   * Return the ANSI standard SQL column type.
   *
   * @param dbPolicy a value of type 'DatabasePolicy'
   * @return a value of type 'String'
   */
  public String getSQLColumnType(DatabasePolicy dbPolicy)
    {
    return "DOUBLE";
    }


  public Object optimisticLockDefaultValue()
    {
    return new Double(0);
    }

  public JoinColumn buildJoinColumn()
    {
    return new DoubleJoinColumn(this.getColumnName(),
                                this.getSetter());
    }


  } // DoubleColumnSpec