public static String encode(String s) 
{
        String str = null;
        try {
            str = encode(s, dfltEncName);
        } catch (UnsupportedEncodingException e) {
            // The system should always have the platform default
        }
        return str;
}

Translates a string into x-www-form-urlencoded format. This method uses the platform's default encoding as the encoding scheme to obtain the bytes for unsafe characters.

 public static String encode(String s,
    String enc) throws UnsupportedEncodingException 
{
        boolean needToChange = false;
        StringBuffer out = new StringBuffer(s.length());
        Charset charset;
        CharArrayWriter charArrayWriter = new CharArrayWriter();
        if (enc == null)
            throw new NullPointerException("charsetName");
        try {
            charset = Charset.forName(enc);
        } catch (IllegalCharsetNameException e) {
            throw new UnsupportedEncodingException(enc);
        } catch (UnsupportedCharsetException e) {
            throw new UnsupportedEncodingException(enc);
        }
        for (int i = 0; i <  s.length();) {
            int c = (int) s.charAt(i);
            //System.out.println("Examining character: " + c);
            if (dontNeedEncoding.get(c)) {
                if (c == ' ") {
                    c = '+";
                    needToChange = true;
                }
                //System.out.println("Storing: " + c);
                out.append((char)c);
                i++;
            } else {
                // convert to external encoding before hex conversion
                do {
                    charArrayWriter.write(c);
                    /*
                     * If this character represents the start of a Unicode
                     * surrogate pair, then pass in two characters. It's not
                     * clear what should be done if a bytes reserved in the
                     * surrogate pairs range occurs outside of a legal
                     * surrogate pair. For now, just treat it as if it were
                     * any other character.
                     */
                    if (c  >= 0xD800 && c < = 0xDBFF) {
                        /*
                          System.out.println(Integer.toHexString(c)
                          + " is high surrogate");
                        */
                        if ( (i+1) <  s.length()) {
                            int d = (int) s.charAt(i+1);
                            /*
                              System.out.println("\tExamining "
                              + Integer.toHexString(d));
                            */
                            if (d  >= 0xDC00 && d < = 0xDFFF) {
                                /*
                                  System.out.println("\t"
                                  + Integer.toHexString(d)
                                  + " is low surrogate");
                                */
                                charArrayWriter.write(d);
                                i++;
                            }
                        }
                    }
                    i++;
                } while (i <  s.length() && !dontNeedEncoding.get((c = (int) s.charAt(i))));
                charArrayWriter.flush();
                String str = new String(charArrayWriter.toCharArray());
                byte[] ba = str.getBytes(charset);
                for (int j = 0; j <  ba.length; j++) {
                    out.append('%");
                    char ch = Character.forDigit((ba[j]  > > 4) & 0xF, 16);
                    // converting to use uppercase letter as part of
                    // the hex value if ch is a letter.
                    if (Character.isLetter(ch)) {
                        ch -= caseDiff;
                    }
                    out.append(ch);
                    ch = Character.forDigit(ba[j] & 0xF, 16);
                    if (Character.isLetter(ch)) {
                        ch -= caseDiff;
                    }
                    out.append(ch);
                }
                charArrayWriter.reset();
                needToChange = true;
            }
        }
        return (needToChange? out.toString() : s);
}

Translates a string into application/x-www-form-urlencoded format using a specific encoding scheme. This method uses the supplied encoding scheme to obtain the bytes for unsafe characters.

Note: The World Wide Web Consortium Recommendation states that UTF-8 should be used. Not doing so may introduce incompatibilites.