lengthlimitingdocument.java

Java的Web报表库

/**
 * ========================================
 * JFreeReport : a free Java report library
 * ========================================
 *
 * Project Info:  http://www.jfree.org/jfreereport/index.html
 * Project Lead:  Thomas Morgner;
 *
 * (C) Copyright 2000-2003, 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.
 *
 * ---------------------------
 * LengthLimitingDocument.java
 * ---------------------------
 * (C)opyright 2003, by Thomas Morgner and Contributors.
 *
 * Original Author:  Thomas Morgner;
 * Contributor(s):   David Gilbert (for Simba Management Limited);
 *
 * $Id: LengthLimitingDocument.java,v 1.6.2.1 2003/08/24 14:18:14 taqua Exp $
 *
 * Changes
 * -------
 * 22-Jan-2003 : Initial version
 * 05-Feb-2003 : Documentation
 */
package com.jrefinery.report.util;

import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.PlainDocument;

/**
 * This Document restricts the size of the contained plain text to the given number of
 * characters.
 *
 * @author Thomas Morgner
 */
public class LengthLimitingDocument extends PlainDocument
{
  /** The maximum length. */
  private int maxlen;

  /**
   * Creates a new LengthLimitingDocument, with no limitation.
   */
  public LengthLimitingDocument()
  {
    this(-1);
  }

  /**
   * Creates a new LengthLimitingDocument with the given limitation. No more than
   * maxlen characters can be added to the document. If maxlen is negative, then
   * no length check is performed.
   *
   * @param maxlen the maximum number of elements in this document
   */
  public LengthLimitingDocument(final int maxlen)
  {
    super();
    this.maxlen = maxlen;
  }

  /**
   * Sets the maximum number of characters for this document. Existing characters
   * are not removed.
   *
   * @param maxlen the maximum number of characters in this document.
   */
  public void setMaxLength(final int maxlen)
  {
    this.maxlen = maxlen;
  }

  /**
   * Returns the defined maximum number characters for this document.
   * @return the maximum number of characters
   */
  public int getMaxLength()
  {
    return maxlen;
  }

  /**
   * Inserts the string into the document. If the length of the document would
   * violate the maximum characters restriction, then the string is cut down so
   * that
   * @param offs the offset, where the string should be inserted into the document
   * @param str the string that should be inserted
   * @param a the attribute set assigned for the document
   * @throws BadLocationException if the offset is not correct
   */
  public void insertString(final int offs, final String str, final AttributeSet a)
      throws BadLocationException
  {
    if (str == null)
    {
      return;
    }

    if (maxlen < 0)
    {
      super.insertString(offs, str, a);
    }

    final char[] numeric = str.toCharArray();
    final StringBuffer b = new StringBuffer();
    b.append(numeric, 0, Math.min(maxlen, numeric.length));
    super.insertString(offs, b.toString(), a);
  }
}