timestampcolumnspec.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): Jonathan Carlson ([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;
import java.sql.Timestamp;


/**
 *  This subclass of AbstractColumnSpec does Timestamp-specific things.
 *
 *  Timestamps can be used for an optimistic lock (i.e. first save wins).
 *  Optimistic locks do not lock users out of an item while someone goes to
 *  lunch (i.e. leaves an item open for a long time).
 */
public class TimestampColumnSpec
    extends AbstractColumnSpec
  {


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


  protected static Class s_class = Timestamp.class;


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

  public TimestampColumnSpec(
      String    columnName,
      String    getter,
      String    setter,
      Object    defaultValue)
    {
    super(columnName,
          getter,
          setter,
          (Timestamp) defaultValue);
    }

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

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

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


  /* ===============  Instance Methods  =============== */


  /**
   * Override of 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)
    {
    String returnValue = "null";
    Timestamp ts = (Timestamp) obj;
    if (ts != null)
        {
        if (ts.equals(AbstractDomain.CURRENT_TIMESTAMP))
            {
            // Set the return value to now (SYSDATE, GETDATE(), etc...)
            returnValue = dbPolicy.timestampFunction();
            }
        else returnValue = dbPolicy.formatTimestamp(ts);
        }
    return returnValue;
    } // formatForSql(...)


  /**
   * This method goes with encode().  The String parameter must have been
   * created by the encode() method.
   *
   * @param aString a value of type 'String'
   * @return a value of type 'Object' (This actually will be a Timestamp or
   *         null)
   */
  public Object decode(String aString)
    {
    if (aString.trim().equals("null"))
        {
        return null;
        }
    return Timestamp.valueOf(aString);
    }


  public Class getColumnClass()
    {
    return s_class;
    }


  /**
   * Override of the superclass implementation.
   * This ensures we get a Timestamp (instead of a Date or something else)
   * 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.getTimestamp(this.getColumnName());
    }


  /**
   * Return the ANSI standard SQL column type.  This is intended for
   * testing.
   *
   * @param domain a value of type 'AbstractDomain'
   * @return a value of type 'String'
   */
  public String getSQLColumnType(DatabasePolicy dbPolicy)
    {
    return dbPolicy.timestampColumnType();
    }

  public Object optimisticLockDefaultValue()
    {
    return ColumnSpec.DEFAULT_TO_NOW;
    }

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

  } // TimestampColumnSpec