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| 1 | +/* | |
| 2 | + * Copyright (c) 1998, 2006, Oracle and/or its affiliates. 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. Oracle designates this | |
| 8 | + * particular file as subject to the "Classpath" exception as provided | |
| 9 | + * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 22 | + * or visit www.oracle.com if you need additional information or have any | |
| 23 | + * 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 | +} | |