/* * Copyright (c) 1998, 2021, 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.
*/
/** * 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}" through "{@code z}", * "{@code A}" through "{@code Z}", * "{@code 0}" through "{@code 9}", and * "{@code -}", "{@code _}", * "{@code .}", and "{@code *}". The * character "{@code %}" is allowed but is interpreted * as the start of a special escaped sequence. * <p> * The following rules are applied in the conversion: * * <ul> * <li>The alphanumeric characters "{@code a}" through * "{@code z}", "{@code A}" through * "{@code Z}" and "{@code 0}" * through "{@code 9}" remain the same. * <li>The special characters "{@code .}", * "{@code -}", "{@code *}", and * "{@code _}" remain the same. * <li>The plus sign "{@code +}" is converted into a * space character " " . * <li>A sequence of the form "<i>{@code %xy}</i>" 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 charset 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 {@link java.lang.IllegalArgumentException}. * Which approach the decoder takes is left to the * implementation. * * @see Charset#defaultCharset() * * @author Mark Chamness * @author Michael McCloskey * @since 1.2
*/
publicclass URLDecoder {
/** * Do not call.
*/ private URLDecoder() {}
// The default charset static String dfltEncName = URLEncoder.dfltEncName;
/** * Decodes a {@code x-www-form-urlencoded} string. * The default charset is used to determine what characters * are represented by any consecutive sequences of the form * "<i>{@code %xy}</i>". * @param s the {@code String} to decode * @deprecated The resulting string may vary depending on the * default charset. Instead, use the decode(String,String) method * to specify the encoding. * @return the newly decoded {@code String}
*/
@Deprecated publicstatic String decode(String s) {
String str = null;
try {
str = decode(s, dfltEncName);
} catch (UnsupportedEncodingException e) { // The system should always have the default charset
}
return str;
}
/** * Decodes an {@code application/x-www-form-urlencoded} string using * a specific encoding scheme. * * <p> * This method behaves the same as {@linkplain decode(String s, Charset charset)} * except that it will {@linkplain Charset#forName look up the charset} * using the given encoding name. * * @implNote This implementation will throw an {@link java.lang.IllegalArgumentException} * when illegal strings are encountered. * * @param s the {@code String} 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} * @throws 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
*/ publicstatic String decode(String s, String enc) throws UnsupportedEncodingException { if (enc.isEmpty()) { thrownew UnsupportedEncodingException ("URLDecoder: empty string enc parameter");
}
/** * Decodes an {@code application/x-www-form-urlencoded} string using * a specific {@linkplain Charset Charset}. * The supplied charset is used to determine * what characters are represented by any consecutive sequences of the * form "<i>{@code %xy}</i>". * <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 * incompatibilities.</em> * * @implNote This implementation will throw an {@link java.lang.IllegalArgumentException} * when illegal strings are encountered. * * @param s the {@code String} to decode * @param charset the given charset * @return the newly decoded {@code String} * @throws NullPointerException if {@code s} or {@code charset} is {@code null} * @throws IllegalArgumentException if the implementation encounters illegal * characters * @see URLEncoder#encode(java.lang.String, Charset) * @since 10
*/ publicstatic String decode(String s, Charset charset) {
Objects.requireNonNull(charset, "Charset"); boolean needToChange = false; int numChars = s.length();
StringBuilder sb = new StringBuilder(numChars > 500 ? numChars / 2 : numChars); int i = 0;
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 = newbyte[(numChars-i)/3]; int pos = 0;
while ( ((i+2) < numChars) &&
(c=='%')) { int v = Integer.parseInt(s, i + 1, i + 3, 16); if (v < 0) thrownew 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
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