urldecoder.java

这是linux下ssl vpn的实现程序

/*
 *  SSL-Explorer
 *
 *  Copyright (C) 2003-2006 3SP LTD. All Rights Reserved
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version 2 of
 *  the License, or (at your option) any later version.
 *  This program 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public
 *  License along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
			
package com.maverick.http;



public class URLDecoder {

  public static String decode(String s) {

        boolean needToChange = false;
        StringBuffer sb = new StringBuffer();
        int numChars = s.length();
        int i = 0;

        while (i < numChars) {
            char c = s.charAt(i);
            switch (c) {
            case '+':
                sb.append(' ');
                i++;
                needToChange = true;
                break;
            case '%':

                try {

                    byte[] bytes = new byte[(numChars-i)/3];
                    int pos = 0;

                    while ( ((i+2) < numChars) &&
                            (c=='%')) {
                        bytes[pos++] =
                            (byte)Integer.parseInt(s.substring(i+1,i+3),16);
                        i+= 3;
                        if (i < numChars)
                            c = s.charAt(i);
                    }

                    if ((i < numChars) && (c=='%'))
                        throw new IllegalArgumentException(
                         "URLDecoder: Incomplete trailing escape (%) pattern");

                    sb.append(new String(bytes, 0, pos));
                } catch (NumberFormatException e) {
                    throw new IllegalArgumentException(
                    "URLDecoder: Illegal hex characters in escape (%) pattern - "
                    + e.getMessage());
                }
                needToChange = true;
                break;
            default:
                sb.append(c);
                i++;
                break;
            }
        }

        return (needToChange? sb.toString() : s);
    }


}