Codes number up to radix 62 : Base64 « Development Class « Java






  1. Java
  2. Development Class
  3. Base64

Codes number up to radix 62

      
/*
 * Copyright 2000,2005 wingS development team.
 *
 * This file is part of wingS (http://wingsframework.org).
 *
 * wingS 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.
 *
 * Please see COPYING for the complete licence.
 */

import java.util.StringTokenizer;

/**
 * Some string manipulation utilities.
 *
 * @author <a href="mailto:haaf@mercatis.de">Armin Haaf</a>
 */
public class StringUtil {

  private final static char[] ALPHAS = {
      'a', 'b',
      'c', 'd', 'e', 'f', 'g', 'h',
      'i', 'j', 'k', 'l', 'm', 'n',
      'o', 'p', 'q', 'r', 's', 't',
      'u', 'v', 'w', 'x', 'y', 'z',
  };

  /**
   * All possible digits for representing a number as a String
   * This is conservative and does not include 'special'
   * characters since some browsers don't handle them right.
   * The IE for instance seems to be case insensitive in class
   * names for CSSs. Grrr.
   */
  private final static char[] DIGITS = {
      '0', '1', '2', '3', '4', '5',
      '6', '7', '8', '9', 'a', 'b',
      'c', 'd', 'e', 'f', 'g', 'h',
      'i', 'j', 'k', 'l', 'm', 'n',
      'o', 'p', 'q', 'r', 's', 't',
      'u', 'v', 'w', 'x', 'y', 'z',
      /* This %@&!-IE is case insensitive for certain
       * URLs and IDs
       * 'A' , 'B' ,
       * 'C' , 'D' , 'E' , 'F' , 'G' , 'H' ,
       * 'I' , 'J' , 'K' , 'L' , 'M' , 'N' ,
       * 'O' , 'P' , 'Q' , 'R' , 'S' , 'T' ,
       * 'U' , 'V' , 'W' , 'X' , 'Y' , 'Z'
       */
  };

  public static final int MAX_RADIX = DIGITS.length;

  /**
   * Codes number up to radix 62.
   * Note, this method is only public for backward compatiblity. don't
   * use it.
   *
   * @param minDigits returns a string with a least minDigits digits
   */
  public static String toString(long i, int radix, int minDigits) {
      char[] buf = new char[65];

      radix = Math.min(Math.abs(radix), MAX_RADIX);
      minDigits = Math.min(buf.length - 1, Math.abs(minDigits));


      int charPos = buf.length - 1;

      boolean negative = (i < 0);
      if (negative) {
          i = -i;
      }

      while (i >= radix) {
          buf[charPos--] = DIGITS[(int) (i % radix)];
          i /= radix;
      }
      buf[charPos] = DIGITS[(int) i];

      // if minimum length of the result string is set, pad it with the
      // zero-representation (that is: '0')
      while (charPos > buf.length - minDigits)
          buf[--charPos] = DIGITS[0];

      if (negative) {
          buf[--charPos] = '-';
      }

      return new String(buf, charPos, buf.length - charPos);
  }

  
}








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