1 /* URLDecoder.java -- Class to decode URL's from encoded form. 2 Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc. 3 4 This file is part of GNU Classpath. 5 6 GNU Classpath is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2, or (at your option) 9 any later version. 10 11 GNU Classpath is distributed in the hope that it will be useful, but 12 WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with GNU Classpath; see the file COPYING. If not, write to the 18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19 02110-1301 USA. 20 21 Linking this library statically or dynamically with other modules is 22 making a combined work based on this library. Thus, the terms and 23 conditions of the GNU General Public License cover the whole 24 combination. 25 26 As a special exception, the copyright holders of this library give you 27 permission to link this library with independent modules to produce an 28 executable, regardless of the license terms of these independent 29 modules, and to copy and distribute the resulting executable under 30 terms of your choice, provided that you also meet, for each linked 31 independent module, the terms and conditions of the license of that 32 module. An independent module is a module which is not derived from 33 or based on this library. If you modify this library, you may extend 34 this exception to your version of the library, but you are not 35 obligated to do so. If you do not wish to do so, delete this 36 exception statement from your version. */ 37 38 package java.net; 39 40 import gnu.java.lang.CPStringBuilder; 41 42 import java.io.UnsupportedEncodingException; 43 44 45 /** 46 * This utility class contains static methods that converts a 47 * string encoded in the x-www-form-urlencoded format to the original 48 * text. The x-www-form-urlencoded format replaces certain disallowed 49 * characters with encoded equivalents. All upper case and lower case 50 * letters in the US alphabet remain as is, the space character (' ') 51 * is replaced with '+' sign, and all other characters are converted to a 52 * "%XX" format where XX is the hexadecimal representation of that character 53 * in a given character encoding (default is "UTF-8"). 54 * <p> 55 * This method is very useful for decoding strings sent to CGI scripts 56 * 57 * Written using on-line Java Platform 1.2/1.4 API Specification. 58 * Status: Believed complete and correct. 59 * 60 * @since 1.2 61 * 62 * @author Warren Levy (warrenl@cygnus.com) 63 * @author Aaron M. Renn (arenn@urbanophile.com) (documentation comments) 64 * @author Mark Wielaard (mark@klomp.org) 65 */ 66 public class URLDecoder 67 { 68 /** 69 * Public contructor. Note that this class has only static methods. 70 */ URLDecoder()71 public URLDecoder() 72 { 73 } 74 75 /** 76 * This method translates the passed in string from x-www-form-urlencoded 77 * format using the default encoding "UTF-8" to decode the hex encoded 78 * unsafe characters. 79 * 80 * @param s the String to convert 81 * 82 * @return the converted String 83 * 84 * @deprecated 85 */ decode(String s)86 public static String decode(String s) 87 { 88 try 89 { 90 return decode(s, "UTF-8"); 91 } 92 catch (UnsupportedEncodingException uee) 93 { 94 // Should never happen since UTF-8 encoding should always be supported 95 return s; 96 } 97 } 98 99 /** 100 * This method translates the passed in string from x-www-form-urlencoded 101 * format using the given character encoding to decode the hex encoded 102 * unsafe characters. 103 * 104 * This implementation will decode the string even if it contains 105 * unsafe characters (characters that should have been encoded) or if the 106 * two characters following a % do not represent a hex encoded byte. 107 * In those cases the unsafe character or the % character will be added 108 * verbatim to the decoded result. 109 * 110 * @param s the String to convert 111 * @param encoding the character encoding to use the decode the hex encoded 112 * unsafe characters 113 * 114 * @return the converted String 115 * 116 * @exception UnsupportedEncodingException If the named encoding is not 117 * supported 118 * 119 * @since 1.4 120 */ decode(String s, String encoding)121 public static String decode(String s, String encoding) 122 throws UnsupportedEncodingException 123 { 124 // First convert all '+' characters to spaces. 125 String str = s.replace('+', ' '); 126 127 // Then go through the whole string looking for byte encoded characters 128 int i; 129 int start = 0; 130 byte[] bytes = null; 131 int length = str.length(); 132 CPStringBuilder result = new CPStringBuilder(length); 133 while ((i = str.indexOf('%', start)) >= 0) 134 { 135 // Add all non-encoded characters to the result buffer 136 result.append(str.substring(start, i)); 137 start = i; 138 139 // Get all consecutive encoded bytes 140 while ((i + 2 < length) && (str.charAt(i) == '%')) 141 i += 3; 142 143 // Decode all these bytes 144 if ((bytes == null) || (bytes.length < ((i - start) / 3))) 145 bytes = new byte[((i - start) / 3)]; 146 147 int index = 0; 148 try 149 { 150 while (start < i) 151 { 152 String sub = str.substring(start + 1, start + 3); 153 bytes[index] = (byte) Integer.parseInt(sub, 16); 154 index++; 155 start += 3; 156 } 157 } 158 catch (NumberFormatException nfe) 159 { 160 // One of the hex encoded strings was bad 161 } 162 163 // Add the bytes as characters according to the given encoding 164 result.append(new String(bytes, 0, index, encoding)); 165 166 // Make sure we skip to just after a % sign 167 // There might not have been enough encoded characters after the % 168 // or the hex chars were not actually hex chars (NumberFormatException) 169 if (start < length && s.charAt(start) == '%') 170 { 171 result.append('%'); 172 start++; 173 } 174 } 175 176 // Add any characters left 177 if (start < str.length()) 178 result.append(str.substring(start)); 179 180 return result.toString(); 181 } 182 } // class URLDecoder 183