001/* URLEncoder.java -- Class to convert strings to a properly encoded URL 002 Copyright (C) 1998, 1999, 2001, 2002, 2003 Free Software Foundation, Inc. 003 004This file is part of GNU Classpath. 005 006GNU Classpath is free software; you can redistribute it and/or modify 007it under the terms of the GNU General Public License as published by 008the Free Software Foundation; either version 2, or (at your option) 009any later version. 010 011GNU Classpath is distributed in the hope that it will be useful, but 012WITHOUT ANY WARRANTY; without even the implied warranty of 013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014General Public License for more details. 015 016You should have received a copy of the GNU General Public License 017along with GNU Classpath; see the file COPYING. If not, write to the 018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 01902110-1301 USA. 020 021Linking this library statically or dynamically with other modules is 022making a combined work based on this library. Thus, the terms and 023conditions of the GNU General Public License cover the whole 024combination. 025 026As a special exception, the copyright holders of this library give you 027permission to link this library with independent modules to produce an 028executable, regardless of the license terms of these independent 029modules, and to copy and distribute the resulting executable under 030terms of your choice, provided that you also meet, for each linked 031independent module, the terms and conditions of the license of that 032module. An independent module is a module which is not derived from 033or based on this library. If you modify this library, you may extend 034this exception to your version of the library, but you are not 035obligated to do so. If you do not wish to do so, delete this 036exception statement from your version. */ 037 038package java.net; 039 040import gnu.java.lang.CPStringBuilder; 041 042import java.io.UnsupportedEncodingException; 043 044 045/* 046 * Written using on-line Java Platform 1.2/1.4 API Specification, as well 047 * as "The Java Class Libraries", 2nd edition (Addison-Wesley, 1998). 048 * Status: Believed complete and correct. 049 */ 050 051/** 052 * This utility class contains static methods that converts a 053 * string into a fully encoded URL string in x-www-form-urlencoded 054 * format. This format replaces certain disallowed characters with 055 * encoded equivalents. All upper case and lower case letters in the 056 * US alphabet remain as is, the space character (' ') is replaced with 057 * '+' sign, and all other characters are converted to a "%XX" format 058 * where XX is the hexadecimal representation of that character in a 059 * certain encoding (by default, the platform encoding, though the 060 * standard is "UTF-8"). 061 * <p> 062 * This method is very useful for encoding strings to be sent to CGI scripts 063 * 064 * @author Aaron M. Renn (arenn@urbanophile.com) 065 * @author Warren Levy (warrenl@cygnus.com) 066 * @author Mark Wielaard (mark@klomp.org) 067 */ 068public class URLEncoder 069{ 070 /** 071 * This method translates the passed in string into x-www-form-urlencoded 072 * format using the default encoding. The standard encoding is 073 * "UTF-8", and the two-argument form of this method should be used 074 * instead. 075 * 076 * @param s The String to convert 077 * 078 * @return The converted String 079 * 080 * @deprecated 081 */ 082 public static String encode(String s) 083 { 084 try 085 { 086 // We default to 8859_1 for compatibility with the same 087 // default elsewhere in the library. 088 return encode(s, System.getProperty("file.encoding", "8859_1")); 089 } 090 catch (UnsupportedEncodingException uee) 091 { 092 // Should never happen since default should always be supported 093 return s; 094 } 095 } 096 097 /** 098 * This method translates the passed in string into x-www-form-urlencoded 099 * format using the character encoding to hex-encode the unsafe characters. 100 * 101 * @param s The String to convert 102 * @param encoding The encoding to use for unsafe characters 103 * 104 * @return The converted String 105 * 106 * @exception UnsupportedEncodingException If the named encoding is not 107 * supported 108 * 109 * @since 1.4 110 */ 111 public static String encode(String s, String encoding) 112 throws UnsupportedEncodingException 113 { 114 int length = s.length(); 115 int start = 0; 116 int i = 0; 117 118 CPStringBuilder result = new CPStringBuilder(length); 119 while (true) 120 { 121 while (i < length && isSafe(s.charAt(i))) 122 i++; 123 124 // Safe character can just be added 125 result.append(s.substring(start, i)); 126 127 // Are we done? 128 if (i >= length) 129 return result.toString(); 130 else if (s.charAt(i) == ' ') 131 { 132 result.append('+'); // Replace space char with plus symbol. 133 i++; 134 } 135 else 136 { 137 // Get all unsafe characters 138 start = i; 139 char c; 140 while (i < length && (c = s.charAt(i)) != ' ' && ! isSafe(c)) 141 i++; 142 143 // Convert them to %XY encoded strings 144 String unsafe = s.substring(start, i); 145 byte[] bytes = unsafe.getBytes(encoding); 146 for (int j = 0; j < bytes.length; j++) 147 { 148 result.append('%'); 149 int val = bytes[j]; 150 result.append(hex.charAt((val & 0xf0) >> 4)); 151 result.append(hex.charAt(val & 0x0f)); 152 } 153 } 154 start = i; 155 } 156 } 157 158 /** 159 * Private static method that returns true if the given char is either 160 * a uppercase or lowercase letter from 'a' till 'z', or a digit froim 161 * '0' till '9', or one of the characters '-', '_', '.' or '*'. Such 162 * 'safe' character don't have to be url encoded. 163 */ 164 private static boolean isSafe(char c) 165 { 166 return ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') 167 || (c >= '0' && c <= '9') || c == '-' || c == '_' || c == '.' 168 || c == '*'); 169 } 170 171 /** 172 * Private constructor that does nothing. Included to avoid a default 173 * public constructor being created by the compiler. 174 */ 175 private URLEncoder() 176 { 177 } 178 179 /** 180 * Used to convert to hex. We don't use Integer.toHexString, since 181 * it converts to lower case (and the Sun docs pretty clearly 182 * specify upper case here), and because it doesn't provide a 183 * leading 0. 184 */ 185 private static final String hex = "0123456789ABCDEF"; 186}