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src/java.base/share/classes/java/net/URLDecoder.java
239 строк
9 KB
Patrick Strawderman
8353453: URLDecoder should use HexFormat
15 апр 2025, 14:26
15 апр 2025, 14:26
03fd43f
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/* * Copyright (c) 1998, 2025, 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.*; import java.nio.charset.Charset; import java.nio.charset.IllegalCharsetNameException; import java.nio.charset.UnsupportedCharsetException; import java.util.HexFormat; import java.util.Objects; /** * 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 */ public final class URLDecoder { /** * Do not call. */ private URLDecoder() {} /** * 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} * @throws IllegalArgumentException if the implementation encounters malformed * escape sequences */ @Deprecated public static String decode(String s) { return decode(s, Charset.defaultCharset()); } /** * 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. * * @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 * @throws IllegalArgumentException if the implementation encounters malformed * escape sequences * @see URLEncoder#encode(java.lang.String, java.lang.String) * @since 1.4 */ public static String decode(String s, String enc) throws UnsupportedEncodingException { if (enc.isEmpty()) { throw new UnsupportedEncodingException ("URLDecoder: empty string enc parameter"); } try { Charset charset = Charset.forName(enc); return decode(s, charset); } catch (IllegalCharsetNameException | UnsupportedCharsetException e) { throw new UnsupportedEncodingException(enc); } } /** * 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 escape sequences of * the form "<i>{@code %xy}</i>". Erroneous bytes are replaced with the * supplied {@code Charset}'s {@linkplain java.nio.charset.CharsetDecoder##cae * replacement value}. * <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> * * @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 malformed * escape sequences * * @spec https://www.w3.org/TR/html4 HTML 4.01 Specification * @see URLEncoder#encode(java.lang.String, Charset) * @since 10 */ public static 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 = new byte[(numChars-i)/3]; int pos = 0; while ( ((i+2) < numChars) && (c=='%')) { int v = HexFormat.fromHexDigits(s, i + 1, i + 3); 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, charset)); } 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); } }