| /* |
| * Copyright (c) 1998, 2006, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code 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 |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package java.net; |
| |
| import java.io.*; |
| |
| /** |
| * Utility class for HTML form decoding. This class contains static methods |
| * for decoding a String from the <CODE>application/x-www-form-urlencoded</CODE> |
| * MIME format. |
| * <p> |
| * The conversion process is the reverse of that used by the URLEncoder class. It is assumed |
| * that all characters in the encoded string are one of the following: |
| * "<code>a</code>" through "<code>z</code>", |
| * "<code>A</code>" through "<code>Z</code>", |
| * "<code>0</code>" through "<code>9</code>", and |
| * "<code>-</code>", "<code>_</code>", |
| * "<code>.</code>", and "<code>*</code>". The |
| * character "<code>%</code>" is allowed but is interpreted |
| * as the start of a special escaped sequence. |
| * <p> |
| * The following rules are applied in the conversion: |
| * <p> |
| * <ul> |
| * <li>The alphanumeric characters "<code>a</code>" through |
| * "<code>z</code>", "<code>A</code>" through |
| * "<code>Z</code>" and "<code>0</code>" |
| * through "<code>9</code>" remain the same. |
| * <li>The special characters "<code>.</code>", |
| * "<code>-</code>", "<code>*</code>", and |
| * "<code>_</code>" remain the same. |
| * <li>The plus sign "<code>+</code>" is converted into a |
| * space character "<code> </code>" . |
| * <li>A sequence of the form "<code>%<i>xy</i></code>" will be |
| * treated as representing a byte where <i>xy</i> is the two-digit |
| * hexadecimal representation of the 8 bits. Then, all substrings |
| * that contain one or more of these byte sequences consecutively |
| * will be replaced by the character(s) whose encoding would result |
| * in those consecutive bytes. |
| * The encoding scheme used to decode these characters may be specified, |
| * or if unspecified, the default encoding of the platform will be used. |
| * </ul> |
| * <p> |
| * There are two possible ways in which this decoder could deal with |
| * illegal strings. It could either leave illegal characters alone or |
| * it could throw an <tt>{@link java.lang.IllegalArgumentException}</tt>. |
| * Which approach the decoder takes is left to the |
| * implementation. |
| * |
| * @author Mark Chamness |
| * @author Michael McCloskey |
| * @since 1.2 |
| */ |
| |
| public class URLDecoder { |
| |
| // The platform default encoding |
| static String dfltEncName = URLEncoder.dfltEncName; |
| |
| /** |
| * Decodes a <code>x-www-form-urlencoded</code> string. |
| * The platform's default encoding is used to determine what characters |
| * are represented by any consecutive sequences of the form |
| * "<code>%<i>xy</i></code>". |
| * @param s the <code>String</code> to decode |
| * @deprecated The resulting string may vary depending on the platform's |
| * default encoding. Instead, use the decode(String,String) method |
| * to specify the encoding. |
| * @return the newly decoded <code>String</code> |
| */ |
| @Deprecated |
| public static String decode(String s) { |
| |
| String str = null; |
| |
| try { |
| str = decode(s, dfltEncName); |
| } catch (UnsupportedEncodingException e) { |
| // The system should always have the platform default |
| } |
| |
| return str; |
| } |
| |
| /** |
| * Decodes a <code>application/x-www-form-urlencoded</code> string using a specific |
| * encoding scheme. |
| * The supplied encoding is used to determine |
| * what characters are represented by any consecutive sequences of the |
| * form "<code>%<i>xy</i></code>". |
| * <p> |
| * <em><strong>Note:</strong> The <a href= |
| * "http://www.w3.org/TR/html40/appendix/notes.html#non-ascii-chars"> |
| * World Wide Web Consortium Recommendation</a> states that |
| * UTF-8 should be used. Not doing so may introduce |
| * incompatibilites.</em> |
| * |
| * @param s the <code>String</code> to decode |
| * @param enc The name of a supported |
| * <a href="../lang/package-summary.html#charenc">character |
| * encoding</a>. |
| * @return the newly decoded <code>String</code> |
| * @exception UnsupportedEncodingException |
| * If character encoding needs to be consulted, but |
| * named character encoding is not supported |
| * @see URLEncoder#encode(java.lang.String, java.lang.String) |
| * @since 1.4 |
| */ |
| public static String decode(String s, String enc) |
| throws UnsupportedEncodingException{ |
| |
| boolean needToChange = false; |
| int numChars = s.length(); |
| StringBuffer sb = new StringBuffer(numChars > 500 ? numChars / 2 : numChars); |
| int i = 0; |
| |
| if (enc.length() == 0) { |
| throw new UnsupportedEncodingException ("URLDecoder: empty string enc parameter"); |
| } |
| |
| char c; |
| byte[] bytes = null; |
| while (i < numChars) { |
| c = s.charAt(i); |
| switch (c) { |
| case '+': |
| sb.append(' '); |
| i++; |
| needToChange = true; |
| break; |
| case '%': |
| /* |
| * Starting with this instance of %, process all |
| * consecutive substrings of the form %xy. Each |
| * substring %xy will yield a byte. Convert all |
| * consecutive bytes obtained this way to whatever |
| * character(s) they represent in the provided |
| * encoding. |
| */ |
| |
| try { |
| |
| // (numChars-i)/3 is an upper bound for the number |
| // of remaining bytes |
| if (bytes == null) |
| bytes = new byte[(numChars-i)/3]; |
| int pos = 0; |
| |
| while ( ((i+2) < numChars) && |
| (c=='%')) { |
| int v = Integer.parseInt(s.substring(i+1,i+3),16); |
| if (v < 0) |
| throw new IllegalArgumentException("URLDecoder: Illegal hex characters in escape (%) pattern - negative value"); |
| bytes[pos++] = (byte) v; |
| i+= 3; |
| if (i < numChars) |
| c = s.charAt(i); |
| } |
| |
| // A trailing, incomplete byte encoding such as |
| // "%x" will cause an exception to be thrown |
| |
| if ((i < numChars) && (c=='%')) |
| throw new IllegalArgumentException( |
| "URLDecoder: Incomplete trailing escape (%) pattern"); |
| |
| sb.append(new String(bytes, 0, pos, enc)); |
| } 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); |
| } |
| } |
