libjava/java/net/URLEncoder.java

   1 // URLEncoder.java - Provides a method for encoding strings according to
   2 //                   application/x-www-form-urlencoded MIME type.
   3
   4 /* Copyright (C) 1999  Cygnus Solutions
   5
   6    This file is part of libgcj.
   7
   8 This software is copyrighted work licensed under the terms of the
   9 Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
  10 details.  */
  11
  12 package java.net;
  13 import java.io.UnsupportedEncodingException;
  14
  15 /**
  16  * @author Warren Levy <warrenl@cygnus.com>
  17  * @date April 22, 1999.
  18  */
  19
  20 /**
  21  * Written using on-line Java Platform 1.2 API Specification, as well
  22  * as "The Java Class Libraries", 2nd edition (Addison-Wesley, 1998).
  23  * Status:  Believed complete and correct.
  24  */
  25
  26 public class URLEncoder
  27 {
  28   // This method, per the JCL, is conservative in that it encodes
  29   // some "allowable" characters as % triplets.
  30   public static String encode(String s)
  31   {
  32     // Get the bytes in ISO-Latin-1 (i.e. 8859_1) per the JCL.
  33     // Even though it is the default in most cases, it's specified here
  34     // just in case System.getProperty("file.encoding") is not "8859_1".
  35     String result = "";
  36     try
  37       {
  38         byte[] buf = s.getBytes("8859_1");
  39         int start = 0;
  40         for (int i = 0; i < buf.length; i++)
  41           // For efficiency, check the byte in order of most likely
  42           // possibility so as to minimize the number of comparisons.
  43           // Hence, exclude all the alphanumeric & allowed special chars first.
  44           if ((buf[i] >= 'a' && buf[i] <= 'z') ||
  45               (buf[i] >= 'A' && buf[i] <= 'Z') ||
  46               (buf[i] >= '0' && buf[i] <= '9') ||
  47               buf[i] == '-' || buf[i] == '_' || buf[i] == '.' || buf[i] == '*')
  48             ; // This is the most likely case so exclude first for efficiency.
  49           else if (buf[i] == ' ')
  50             buf[i] = (byte) '+';  // Replace space char with plus symbol.
  51           else
  52             {
  53               result = result + new String(buf, start, i - start, "8859_1") +
  54                         "%" + Integer.toHexString(((int) buf[i]) & 0xFF);
  55               start = i + 1;
  56             }
  57
  58         // Append remainder of allowable chars from the string, if any.
  59         if (start < buf.length)
  60           result = result +
  61                    new String(buf, start, buf.length - start, "8859_1");
  62       }
  63     catch (UnsupportedEncodingException ex)
  64       {
  65         // This should never happen as "8859_1" is the default encoding.
  66         return s;
  67       }
  68
  69     return result;
  70   }
  71 }