stringcolumnspec.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;


/**
 * This subclass of AbstractColumnSpec does String-specific things.
 */
public class StringColumnSpec
    extends AbstractColumnSpec
  {


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

  protected static Class s_class = String.class;


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

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

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

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

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


  /**
   * This method overrides the superclass implementation.  A string of
   * "null" is returned if object is null, otherwise it returns a String
   * with quotes around it.  Internal single quotes are converted to
   * two single quotes and the string is wrapped in single quotes.
   *
   * @param aValueObject a value of type 'ValueObject'
   * @return a value of type 'String'
   */
  public String formatForSql(Object obj, DatabasePolicy dbPolicy)
    {
    String returnValue = "null";
    if (obj != null)
        {
        returnValue = JDBCHelper.delimitString((String)obj, "'");
        }
    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 String or null)
   */
  public Object decode(String aString)
    {
    if (aString.trim().equals("null"))
        {
        return null;
        }
    return aString;
    }


  public Class getColumnClass()
    {
    return s_class;
    }


  /**
   * Return a String from JDBCHelper.  If String is one blank, return an
   * empty string.  This resolves a strange issue with SQLServer (and maybe
   * Sybase) that keeps returning empty or whitespace strings as one blank
   * character.  If one blank is truly desired, then maybe this should go
   * into the DatabasePolicy, but then we'll have differing behavior when
   * switching databases.
   *
   * @param helper a value of type 'JDBCHelper'
   * @return a value of type 'Object'
   * @exception SQLException if an error occurs in JDBCHelper
   */
  public Object getColumnValueFrom(JDBCHelper helper)
          throws SQLException
    {
    String returnValue = helper.getString(this.getColumnName());
    // This if is here to solve a problem with SQLServer where an empty
    // string is returned as a one character blank string.
    if (returnValue != null &&
        returnValue.equals(" "))
        {
        returnValue = "";
        }
    return returnValue;
    }


  /**
   * This is an override of the superclass implementation.  This method adds
   * a check to make sure the string is not empty or blank.
   *
   * @param aPO a value of type 'PersistentObject'
   * @return a value of type 'Object'
   * @exception MissingAttributeException if an error occurs
   */
  public Object validateRequired(PersistentObject aPO)
          throws MissingAttributeException
    {
    String value = (String) super.validateRequired(aPO);
    // a null value tells us it had to be non-required or an error would
    // have been thrown.
    if (value != null &&
        value.trim().length() == 0)
        {
        throw new MissingAttributeException(
            "Required attribute - "
            + this.getColumnName()
            + "- is an empty string value.");
        }
    return value;
    } // validateRequired(aPersistentObject)


  /**
   * Return the ANSI standard SQL column type.  This was written to support
   * the test suites.  If there is no standard that will work across
   * platforms, then we'll add a method to dbPolicy and return its' value.
   *
   * @param dbPolicy a value of type 'DatabasePolicy'
   * @return a value of type 'String'
   */
  public String getSQLColumnType(DatabasePolicy dbPolicy)
    {
    return "VARCHAR(255)";
    }


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


  } // StringColumnSpec