csvquoter.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 2000-2003, 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.
 *
 * --------------
 * CSVQuoter.java
 * --------------
 * (C)opyright 2003, by Thomas Morgner and Contributors.
 *
 * Original Author:  Thomas Morgner;
 * Contributor(s):   David Gilbert (for Simba Management Limited);
 *
 * $Id: CSVQuoter.java,v 1.2 2003/08/24 15:06:42 taqua Exp $
 *
 * Changes
 * -------
 * 18-Jan-2003 : Initial Version
 * 09-Feb-2003 : Documentation
 * 24-Feb-2003 : Fixed Checkstyle issues (DG);
 *
 */

package org.jfree.report.modules.output.csv;

/**
 * The <code>CSVQuoter</code> is a helper class to encode a string for the CSV file format.
 *
 * @author Thomas Morgner.
 */
public class CSVQuoter
{
  /** The separator used in the CSV file. */
  private String separator;

  /**
   * Creates a new CSVQuoter, which uses a comma as the default separator.
   */
  public CSVQuoter()
  {
    this(",");
  }

  /**
   * Creates a new <code>CSVQuoter</code>, which uses the defined separator.
   *
   * @param separator  the separator.
   *
   * @throws NullPointerException if the given separator is <code>null</code>.
   */
  public CSVQuoter(final String separator)
  {
    setSeparator(separator);
  }

  /**
   * Encodes the string, so that the string can safely be used in CSV files.
   * If the string does not need quoting, the original string is returned unchanged.
   *
   * @param original  the unquoted string.
   *
   * @return The quoted string
   */
  public String doQuoting(final String original)
  {
    if (isQuotingNeeded(original))
    {
      final StringBuffer retval = new StringBuffer();
      retval.append("\"");
      applyQuote(retval, original);
      retval.append("\"");
      return retval.toString();
    }
    else
    {
      return original;
    }
  }

  /**
   * Decodes the string, so that all escape sequences get removed.
   * If the string was not quoted, then the string is returned unchanged.
   *
   * @param nativeString  the quoted string.
   *
   * @return The unquoted string.
   */
  public String undoQuoting(final String nativeString)
  {
    if (isQuotingNeeded(nativeString))
    {
      final StringBuffer b = new StringBuffer(nativeString.length());
      final int length = nativeString.length() - 1;
      int start = 1;

      int pos = start;
      while (pos != -1)
      {
        pos = nativeString.indexOf("\"\"", start);
        if (pos == -1)
        {
          b.append(nativeString.substring(start, length));
        }
        else
        {
          b.append(nativeString.substring(start, pos));
          start = pos + 1;
        }
      }
      return b.toString();
    }
    else
    {
      return nativeString;
    }
  }

  /**
   * Tests, whether this string needs to be quoted. A string is encoded if
   * the string contains a newline character, a quote character or the defined
   * separator.
   *
   * @param str the string that should be tested.
   * @return true, if quoting needs to be applied, false otherwise.
   */
  private boolean isQuotingNeeded(final String str)
  {
    if (str.indexOf(separator) != -1)
    {
      return true;
    }
    if (str.indexOf('\n') != -1)
    {
      return true;
    }
    if (str.indexOf('\"', 1) != -1)
    {
      return true;
    }
    return false;
  }

  /**
   * Applies the quoting to a given string, and stores the result in the
   * StringBuffer <code>b</code>.
   *
   * @param b the result buffer
   * @param original the string, that should be quoted.
   */
  private void applyQuote(final StringBuffer b, final String original)
  {
    // This solution needs improvements. Copy blocks instead of single
    // characters.
    final int length = original.length();

    for (int i = 0; i < length; i++)
    {
      final char c = original.charAt(i);
      if (c == '"')
      {
        b.append("\"\"");
      }
      else
      {
        b.append(c);
      }
    }
  }

  /**
   * Gets the separator used in this quoter and the CSV file.
   *
   * @return the separator (never <code>null</code>).
   */
  public String getSeparator()
  {
    return separator;
  }

  /**
   * Defines the separator, which is used in the CSV file. If you use
   * different separators for quoting and writing, the resulting file will
   * be invalid.
   *
   * @param separator  the separator (<code>null</code> not permitted).
   */
  public void setSeparator(final String separator)
  {
    if (separator == null)
    {
      throw new NullPointerException();
    }
    this.separator = separator;
  }
}