| J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1998-2006 Sun Microsystems, Inc. All Rights Reserved. |
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 | * |
| 5 | * This code is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License version 2 only, as |
| 7 | * published by the Free Software Foundation. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun in the LICENSE file that accompanied this code. |
| 10 | * |
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 14 | * version 2 for more details (a copy is included in the LICENSE file that |
| 15 | * accompanied this code). |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License version |
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 20 | * |
| 21 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package java.net; |
| 27 | |
| 28 | import java.io.*; |
| 29 | |
| 30 | /** |
| 31 | * Utility class for HTML form decoding. This class contains static methods |
| 32 | * for decoding a String from the <CODE>application/x-www-form-urlencoded</CODE> |
| 33 | * MIME format. |
| 34 | * <p> |
| 35 | * The conversion process is the reverse of that used by the URLEncoder class. It is assumed |
| 36 | * that all characters in the encoded string are one of the following: |
| 37 | * "<code>a</code>" through "<code>z</code>", |
| 38 | * "<code>A</code>" through "<code>Z</code>", |
| 39 | * "<code>0</code>" through "<code>9</code>", and |
| 40 | * "<code>-</code>", "<code>_</code>", |
| 41 | * "<code>.</code>", and "<code>*</code>". The |
| 42 | * character "<code>%</code>" is allowed but is interpreted |
| 43 | * as the start of a special escaped sequence. |
| 44 | * <p> |
| 45 | * The following rules are applied in the conversion: |
| 46 | * <p> |
| 47 | * <ul> |
| 48 | * <li>The alphanumeric characters "<code>a</code>" through |
| 49 | * "<code>z</code>", "<code>A</code>" through |
| 50 | * "<code>Z</code>" and "<code>0</code>" |
| 51 | * through "<code>9</code>" remain the same. |
| 52 | * <li>The special characters "<code>.</code>", |
| 53 | * "<code>-</code>", "<code>*</code>", and |
| 54 | * "<code>_</code>" remain the same. |
| 55 | * <li>The plus sign "<code>+</code>" is converted into a |
| 56 | * space character "<code> </code>" . |
| 57 | * <li>A sequence of the form "<code>%<i>xy</i></code>" will be |
| 58 | * treated as representing a byte where <i>xy</i> is the two-digit |
| 59 | * hexadecimal representation of the 8 bits. Then, all substrings |
| 60 | * that contain one or more of these byte sequences consecutively |
| 61 | * will be replaced by the character(s) whose encoding would result |
| 62 | * in those consecutive bytes. |
| 63 | * The encoding scheme used to decode these characters may be specified, |
| 64 | * or if unspecified, the default encoding of the platform will be used. |
| 65 | * </ul> |
| 66 | * <p> |
| 67 | * There are two possible ways in which this decoder could deal with |
| 68 | * illegal strings. It could either leave illegal characters alone or |
| 69 | * it could throw an <tt>{@link java.lang.IllegalArgumentException}</tt>. |
| 70 | * Which approach the decoder takes is left to the |
| 71 | * implementation. |
| 72 | * |
| 73 | * @author Mark Chamness |
| 74 | * @author Michael McCloskey |
| 75 | * @since 1.2 |
| 76 | */ |
| 77 | |
| 78 | public class URLDecoder { |
| 79 | |
| 80 | // The platform default encoding |
| 81 | static String dfltEncName = URLEncoder.dfltEncName; |
| 82 | |
| 83 | /** |
| 84 | * Decodes a <code>x-www-form-urlencoded</code> string. |
| 85 | * The platform's default encoding is used to determine what characters |
| 86 | * are represented by any consecutive sequences of the form |
| 87 | * "<code>%<i>xy</i></code>". |
| 88 | * @param s the <code>String</code> to decode |
| 89 | * @deprecated The resulting string may vary depending on the platform's |
| 90 | * default encoding. Instead, use the decode(String,String) method |
| 91 | * to specify the encoding. |
| 92 | * @return the newly decoded <code>String</code> |
| 93 | */ |
| 94 | @Deprecated |
| 95 | public static String decode(String s) { |
| 96 | |
| 97 | String str = null; |
| 98 | |
| 99 | try { |
| 100 | str = decode(s, dfltEncName); |
| 101 | } catch (UnsupportedEncodingException e) { |
| 102 | // The system should always have the platform default |
| 103 | } |
| 104 | |
| 105 | return str; |
| 106 | } |
| 107 | |
| 108 | /** |
| 109 | * Decodes a <code>application/x-www-form-urlencoded</code> string using a specific |
| 110 | * encoding scheme. |
| 111 | * The supplied encoding is used to determine |
| 112 | * what characters are represented by any consecutive sequences of the |
| 113 | * form "<code>%<i>xy</i></code>". |
| 114 | * <p> |
| 115 | * <em><strong>Note:</strong> The <a href= |
| 116 | * "http://www.w3.org/TR/html40/appendix/notes.html#non-ascii-chars"> |
| 117 | * World Wide Web Consortium Recommendation</a> states that |
| 118 | * UTF-8 should be used. Not doing so may introduce |
| 119 | * incompatibilites.</em> |
| 120 | * |
| 121 | * @param s the <code>String</code> to decode |
| 122 | * @param enc The name of a supported |
| 123 | * <a href="../lang/package-summary.html#charenc">character |
| 124 | * encoding</a>. |
| 125 | * @return the newly decoded <code>String</code> |
| 126 | * @exception UnsupportedEncodingException |
| 127 | * If character encoding needs to be consulted, but |
| 128 | * named character encoding is not supported |
| 129 | * @see URLEncoder#encode(java.lang.String, java.lang.String) |
| 130 | * @since 1.4 |
| 131 | */ |
| 132 | public static String decode(String s, String enc) |
| 133 | throws UnsupportedEncodingException{ |
| 134 | |
| 135 | boolean needToChange = false; |
| 136 | int numChars = s.length(); |
| 137 | StringBuffer sb = new StringBuffer(numChars > 500 ? numChars / 2 : numChars); |
| 138 | int i = 0; |
| 139 | |
| 140 | if (enc.length() == 0) { |
| 141 | throw new UnsupportedEncodingException ("URLDecoder: empty string enc parameter"); |
| 142 | } |
| 143 | |
| 144 | char c; |
| 145 | byte[] bytes = null; |
| 146 | while (i < numChars) { |
| 147 | c = s.charAt(i); |
| 148 | switch (c) { |
| 149 | case '+': |
| 150 | sb.append(' '); |
| 151 | i++; |
| 152 | needToChange = true; |
| 153 | break; |
| 154 | case '%': |
| 155 | /* |
| 156 | * Starting with this instance of %, process all |
| 157 | * consecutive substrings of the form %xy. Each |
| 158 | * substring %xy will yield a byte. Convert all |
| 159 | * consecutive bytes obtained this way to whatever |
| 160 | * character(s) they represent in the provided |
| 161 | * encoding. |
| 162 | */ |
| 163 | |
| 164 | try { |
| 165 | |
| 166 | // (numChars-i)/3 is an upper bound for the number |
| 167 | // of remaining bytes |
| 168 | if (bytes == null) |
| 169 | bytes = new byte[(numChars-i)/3]; |
| 170 | int pos = 0; |
| 171 | |
| 172 | while ( ((i+2) < numChars) && |
| 173 | (c=='%')) { |
| 174 | int v = Integer.parseInt(s.substring(i+1,i+3),16); |
| 175 | if (v < 0) |
| 176 | throw new IllegalArgumentException("URLDecoder: Illegal hex characters in escape (%) pattern - negative value"); |
| 177 | bytes[pos++] = (byte) v; |
| 178 | i+= 3; |
| 179 | if (i < numChars) |
| 180 | c = s.charAt(i); |
| 181 | } |
| 182 | |
| 183 | // A trailing, incomplete byte encoding such as |
| 184 | // "%x" will cause an exception to be thrown |
| 185 | |
| 186 | if ((i < numChars) && (c=='%')) |
| 187 | throw new IllegalArgumentException( |
| 188 | "URLDecoder: Incomplete trailing escape (%) pattern"); |
| 189 | |
| 190 | sb.append(new String(bytes, 0, pos, enc)); |
| 191 | } catch (NumberFormatException e) { |
| 192 | throw new IllegalArgumentException( |
| 193 | "URLDecoder: Illegal hex characters in escape (%) pattern - " |
| 194 | + e.getMessage()); |
| 195 | } |
| 196 | needToChange = true; |
| 197 | break; |
| 198 | default: |
| 199 | sb.append(c); |
| 200 | i++; |
| 201 | break; |
| 202 | } |
| 203 | } |
| 204 | |
| 205 | return (needToChange? sb.toString() : s); |
| 206 | } |
| 207 | } |