dateformatparser.java

swing编写的库存管理程序。毕业设计类

/**
 * ========================================
 * JFreeReport : a free Java report library
 * ========================================
 *
 * Project Info:  http://www.jfree.org/jfreereport/index.html
 * Project Lead:  Thomas Morgner;
 *
 * (C) Copyright 2000-2002, by Simba Management Limited and Contributors.
 *
 * This library is free software; you can redistribute it and/or modify it under the terms
 * of the GNU Lesser General Public License as published by the Free Software Foundation;
 * either version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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.
 * See the GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License along with this
 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * ---------------------
 * DateFormatParser.java
 * ---------------------
 * (C)opyright 2000-2002, by Simba Management Limited.
 *
 * $Id: DateFormatParser.java,v 1.2 2003/08/24 15:13:22 taqua Exp $
 *
 * ChangeLog
 * ---------
 * 21-May-2002 : Initial version
 * 06-Jun-2002 : Documentation updated
 * 08-Aug-2002 : Removed unused Imports
 */
package org.jfree.report.filter;

import java.text.DateFormat;
import java.text.Format;
import java.util.Date;

/**
 * Parses a String into a java.util.Date. The string is read from the given datasource
 * and then parsed by the dateformat contained in this FormatParser.
 *
 * @author Thomas Morgner
 */
public class DateFormatParser extends FormatParser
{
  /**
   * Creates a new 'date format parser'.
   */
  public DateFormatParser()
  {
    setDateFormat(DateFormat.getInstance());
  }

  /**
   * Returns the format for this filter. The format object is returned as DateFormat.
   *
   * @return  the formatter.
   *
   * @throws NullPointerException if the given format is null
   */
  public DateFormat getDateFormat()
  {
    return (DateFormat) getFormatter();
  }

  /**
   * Sets the format for the filter.
   *
   * @param format The format.
   *
   * @throws NullPointerException if the given format is null
   */
  public void setDateFormat(final DateFormat format)
  {
    super.setFormatter(format);
  }

  /**
   * Sets the format for the filter. The formater is required to be of type DateFormat.
   *
   * @param format The format.
   *
   * @throws NullPointerException if the given format is null
   * @throws ClassCastException if an invalid formater is set.
   */
  public void setFormatter(final Format format)
  {
    final DateFormat dfmt = (DateFormat) format;
    super.setFormatter(dfmt);
  }

  /**
   * Sets the value that will be displayed if the data source supplies a null value.
   * The nullValue itself can be null to cover the case when no reasonable default value
   * can be defined.
   * <p>
   * The null value for date format parsers is required to be either null or a java.util.Date.
   *
   * @param nullvalue the nullvalue returned when parsing failed.
   *
   * @throws ClassCastException if the value is no date or not null.
   */
  public void setNullValue(final Object nullvalue)
  {
    final Date dt = (Date) nullvalue;
    super.setNullValue(dt);
  }

  /**
   * Checks whether the given value is already a valid result. IF the datasource already returned
   * a valid value, and no parsing is required, a parser can skip the parsing process by returning
   * true in this function.
   *
   * @param o  the value.
   *
   * @return true, if the given value is already an instance of date.
   */
  protected boolean isValidOutput(final Object o)
  {
    return o instanceof Date;
  }
}