Provides a method to encode any string into a URL-safe form : URLDecoder « Network « Java Tutorial






/**
 * 
 * JFreeReport : a free Java reporting library
 * 
 *
 * Project Info:  http://reporting.pentaho.org/
 *
 * (C) Copyright 2001-2007, by Object Refinery Ltd, Pentaho Corporation 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.
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
 * in the United States and other countries.]
 *
 * ------------
 * UTFEncodingUtil.java
 * ------------
 * (C) Copyright 2001-2007, by Object Refinery Ltd, Pentaho Corporation and Contributors.
 */

import java.io.UnsupportedEncodingException;


/**
 * Provides a method to encode any string into a URL-safe form. Non-ASCII characters are first encoded as sequences of
 * two or three bytes, using the UTF-8 algorithm, before being encoded as %HH escapes.
 * <p/>
 * Code is the public example given at http://www.w3.org/International/O-URL-code.html
 *
 * @author Bert Bos
 */
public class UTFEncodingUtil
{
  /**
   * Private Constructor prevents Object Creation.
   */
  private UTFEncodingUtil()
  {
  }

  /**
   * A lookup table.
   */
  private static final String[] hex = {
      "%00", "%01", "%02", "%03", "%04", "%05", "%06", "%07",
      "%08", "%09", "%0A", "%0B", "%0C", "%0D", "%0E", "%0F",
      "%10", "%11", "%12", "%13", "%14", "%15", "%16", "%17",
      "%18", "%19", "%1A", "%1B", "%1C", "%1D", "%1E", "%1F",
      "%20", "%21", "%22", "%23", "%24", "%25", "%26", "%27",
      "%28", "%29", "%2A", "%2B", "%2C", "%2D", "%2E", "%2F",
      "%30", "%31", "%32", "%33", "%34", "%35", "%36", "%37",
      "%38", "%39", "%3A", "%3B", "%3C", "%3D", "%3E", "%3F",
      "%40", "%41", "%42", "%43", "%44", "%45", "%46", "%47",
      "%48", "%49", "%4A", "%4B", "%4C", "%4D", "%4E", "%4F",
      "%50", "%51", "%52", "%53", "%54", "%55", "%56", "%57",
      "%58", "%59", "%5A", "%5B", "%5C", "%5D", "%5E", "%5F",
      "%60", "%61", "%62", "%63", "%64", "%65", "%66", "%67",
      "%68", "%69", "%6A", "%6B", "%6C", "%6D", "%6E", "%6F",
      "%70", "%71", "%72", "%73", "%74", "%75", "%76", "%77",
      "%78", "%79", "%7A", "%7B", "%7C", "%7D", "%7E", "%7F",
      "%80", "%81", "%82", "%83", "%84", "%85", "%86", "%87",
      "%88", "%89", "%8A", "%8B", "%8C", "%8D", "%8E", "%8F",
      "%90", "%91", "%92", "%93", "%94", "%95", "%96", "%97",
      "%98", "%99", "%9A", "%9B", "%9C", "%9D", "%9E", "%9F",
      "%A0", "%A1", "%A2", "%A3", "%A4", "%A5", "%A6", "%A7",
      "%A8", "%A9", "%AA", "%AB", "%AC", "%AD", "%AE", "%AF",
      "%B0", "%B1", "%B2", "%B3", "%B4", "%B5", "%B6", "%B7",
      "%B8", "%B9", "%BA", "%BB", "%BC", "%BD", "%BE", "%BF",
      "%C0", "%C1", "%C2", "%C3", "%C4", "%C5", "%C6", "%C7",
      "%C8", "%C9", "%CA", "%CB", "%CC", "%CD", "%CE", "%CF",
      "%D0", "%D1", "%D2", "%D3", "%D4", "%D5", "%D6", "%D7",
      "%D8", "%D9", "%DA", "%DB", "%DC", "%DD", "%DE", "%DF",
      "%E0", "%E1", "%E2", "%E3", "%E4", "%E5", "%E6", "%E7",
      "%E8", "%E9", "%EA", "%EB", "%EC", "%ED", "%EE", "%EF",
      "%F0", "%F1", "%F2", "%F3", "%F4", "%F5", "%F6", "%F7",
      "%F8", "%F9", "%FA", "%FB", "%FC", "%FD", "%FE", "%FF"
  };

  /**
   * Encode a string according to RFC 1738.
   * <p/>
   * <quote> "...Only alphanumerics [0-9a-zA-Z], the special characters "$-_.+!*'()," [not including the quotes - ed],
   * and reserved characters used for their reserved purposes may be used unencoded within a URL."</quote>
   * <p/>
   * <ul> <li><p>The ASCII characters 'a' through 'z', 'A' through 'Z', and '0' through '9' remain the same.
   * <p/>
   * <li><p>The unreserved characters - _ . ! ~ * ' ( ) remain the same.
   * <p/>
   * <li><p>All other ASCII characters are converted into the 3-character string "%xy", where xy is the two-digit
   * hexadecimal representation of the character code
   * <p/>
   * <li><p>All non-ASCII characters are encoded in two steps: first to a sequence of 2 or 3 bytes, using the UTF-8
   * algorithm; secondly each of these bytes is encoded as "%xx". </ul>
   *
   * @param s The string to be encoded
   * @return The encoded string
   */
  public static String encodeUTF8(final String s)
  {
    final StringBuffer sbuf = new StringBuffer();
    final char[] sChars = s.toCharArray();
    final int len = sChars.length;
    for (int i = 0; i < len; i++)
    {
      final int ch = sChars[i];
      if ('A' <= ch && ch <= 'Z')
      {    // 'A'..'Z'
        sbuf.append((char) ch);
      }
      else if ('a' <= ch && ch <= 'z')
      {  // 'a'..'z'
        sbuf.append((char) ch);
      }
      else if ('0' <= ch && ch <= '9')
      {  // '0'..'9'
        sbuf.append((char) ch);
      }
      else if (ch == '-' || ch == '_'    // unreserved
          || ch == '.' || ch == '!'
          || ch == '~' || ch == '*'
          || ch == '\'' || ch == '('
          || ch == ')')
      {
        sbuf.append((char) ch);
      }
      else if (ch <= 0x007f)
      {    // other ASCII
        sbuf.append(hex[ch]);
      }
      else if (ch <= 0x07FF)
      {    // non-ASCII <= 0x7FF
        sbuf.append(hex[0xc0 | (ch >> 6)]);
        sbuf.append(hex[0x80 | (ch & 0x3F)]);
      }
      else
      {          // 0x7FF < ch <= 0xFFFF
        sbuf.append(hex[0xe0 | (ch >> 12)]);
        sbuf.append(hex[0x80 | ((ch >> 6) & 0x3F)]);
        sbuf.append(hex[0x80 | (ch & 0x3F)]);
      }
    }
    return sbuf.toString();
  }

  /**
   * Encodes a byte-array. The array is expected to contain ASCII characters, or the result may not be valid.
   *
   * @param s the byte array
   * @return the array as encoded string.
   */
  private static String encodeBytes(final byte[] s)
  {
    final StringBuffer sbuf = new StringBuffer();
    final int len = s.length;
    for (int i = 0; i < len; i++)
    {
      final int ch = (s[i] & 0xff);
      if ('A' <= ch && ch <= 'Z')
      {    // 'A'..'Z'
        sbuf.append((char) ch);
      }
      else if ('a' <= ch && ch <= 'z')
      {  // 'a'..'z'
        sbuf.append((char) ch);
      }
      else if ('0' <= ch && ch <= '9')
      {  // '0'..'9'
        sbuf.append((char) ch);
      }
      else if (ch == '-' || ch == '_'    // unreserved
          || ch == '.' || ch == '!'
          || ch == '~' || ch == '*'
          || ch == '\'' || ch == '('
          || ch == ')')
      {
        sbuf.append((char) ch);
      }
      else
      {    // other ASCII
        sbuf.append(hex[ch]);
      }
    }
    return sbuf.toString();
  }

  /**
   * Encodes thh given string using the provided encoding. The encoding must be a valid Java-encoding.
   *
   * @param s        the string that should be encoded.
   * @param encoding the encoding to tranform the string into bytes.
   * @return the encoded string.
   * @throws UnsupportedEncodingException if the specified encoding is not recognized.
   */
  public static String encode(final String s, final String encoding)
      throws UnsupportedEncodingException
  {
    if ("utf-8".equalsIgnoreCase(encoding))
    {
      return encodeUTF8(s);
    }

    return encodeBytes(s.getBytes(encoding));
  }



  /**
   * Decodes the given string using the provided encoding. The encoding must be a valid
   * Java-encoding.
   *
   * @param s        the string that should be encoded.
   * @param encoding the encoding to tranform the bytes into a string.
   * @return the encoded string.
   * @throws UnsupportedEncodingException if the specified encoding is not recognized.
   */
  public static String decode(final String s, final String encoding)
      throws UnsupportedEncodingException
  {
    if ("utf-8".equalsIgnoreCase(encoding))
    {
      return decodeUTF(s);
    }
    // the resulting string will never be greater than the encoded string
    final byte[] result = new byte[s.length()];
    final char[] chars = s.toCharArray();
    int position = 0;

    for (int i = 0; i < chars.length; i++)
    {
      final char ch = chars[i];
      final int b;
      switch (ch)
      {
        case'%':
          final char lch = s.charAt(++i);
          final int hb = (Character.isDigit(lch)
              ? lch - '0'
              : 10 + Character.toLowerCase(lch) - 'a') & 0xF;
          final char hch = s.charAt(++i);
          final int lb = (Character.isDigit(hch)
              ? hch - '0'
              : 10 + Character.toLowerCase(hch) - 'a') & 0xF;
          b = (hb << 4) | lb;
          break;
        case'+':
          b = ' ';
          break;
        default:
          b = ch;
      }
      result[position] = (byte) b;
      position += 1;
    }
    return new String(result, 0, position, encoding);
  }

  /**
   * Decodes the given string using the encoding UTF-8.
   *
   * @param s        the string that should be encoded.
   * @return the encoded string.
   */
  public static String decodeUTF(final String s)
  {
    final StringBuffer sbuf = new StringBuffer();
    final char[] chars = s.toCharArray();
    final int l = chars.length;
    int sumb = 0;
    for (int i = 0, more = -1; i < l; i++)
    {
      /* Get next byte b from URL segment s */
      final int ch = chars[i];
      final int b;
      switch (ch)
      {
        case'%':
          final char lch = s.charAt(++i);
          final int hb = (Character.isDigit(lch)
              ? lch - '0'
              : 10 + Character.toLowerCase(lch) - 'a') & 0xF;
          final char hch = s.charAt(++i);
          final int lb = (Character.isDigit(hch)
              ? hch - '0'
              : 10 + Character.toLowerCase(hch) - 'a') & 0xF;
          b = (hb << 4) | lb;
          break;
        case'+':
          b = ' ';
          break;
        default:
          b = ch;
      }
      /* Decode byte b as UTF-8, sumb collects incomplete chars */
      if ((b & 0xc0) == 0x80)
      {      // 10xxxxxx (continuation byte)
        sumb = (sumb << 6) | (b & 0x3f);  // Add 6 bits to sumb
        if (--more == 0)
        {
          sbuf.append((char) sumb); // Add char to sbuf
        }
      }
      else if ((b & 0x80) == 0x00)
      {    // 0xxxxxxx (yields 7 bits)
        sbuf.append((char) b);      // Store in sbuf
      }
      else if ((b & 0xe0) == 0xc0)
      {    // 110xxxxx (yields 5 bits)
        sumb = b & 0x1f;
        more = 1;        // Expect 1 more byte
      }
      else if ((b & 0xf0) == 0xe0)
      {    // 1110xxxx (yields 4 bits)
        sumb = b & 0x0f;
        more = 2;        // Expect 2 more bytes
      }
      else if ((b & 0xf8) == 0xf0)
      {    // 11110xxx (yields 3 bits)
        sumb = b & 0x07;
        more = 3;        // Expect 3 more bytes
      }
      else if ((b & 0xfc) == 0xf8)
      {    // 111110xx (yields 2 bits)
        sumb = b & 0x03;
        more = 4;        // Expect 4 more bytes
      }
      else /*if ((b & 0xfe) == 0xfc)*/
      {  // 1111110x (yields 1 bit)
        sumb = b & 0x01;
        more = 5;        // Expect 5 more bytes
      }
      /* We don't test if the UTF-8 encoding is well-formed */
    }
    return sbuf.toString();
  }
}








19.4.URLDecoder
19.4.1.URL decoder
19.4.2.URLDecoder 2
19.4.3.URLEncoder: space
19.4.4.URLEncoder: asterisks
19.4.5.URLEncoder:
19.4.6.URLEncoder: plus sign
19.4.7.URLEncoder: slashes
19.4.8.URLEncoder: quotations
19.4.9.URLEncoder: colons(:)
19.4.10.URLEncoder: tildes(~)
19.4.11.URLEncoder: parentheses()
19.4.12.URLEncoder: dot
19.4.13.URLEncoder: equal sign
19.4.14.URLEncoder: ampersands
19.4.15.Converting x-www-form-urlencoded Data
19.4.16.Parse a x-www-form-urlencoded string
19.4.17.Encode a path as required by the URL specification
19.4.18.Decoding and encoding URLs
19.4.19.Provides a method to encode any string into a URL-safe form
19.4.20.Converting text to be used within a URL
19.4.21.URL encoding