Java example source code file (URLDecoder.java)

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Java - Java tags/keywords

deprecated, illegalargumentexception, incomplete, numberformatexception, string, stringbuffer, unsupportedencodingexception, urldecoder

The URLDecoder.java Java example source code

/*
 * Copyright (c) 1998, 2013, 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
 * 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 "{@code %xy}" will be
 *     treated as representing a byte where <i>xy 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 {@link java.lang.IllegalArgumentException}.
 * 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} string.
     * The platform's default encoding is used to determine what characters
     * are represented by any consecutive sequences of the form
     * "<i>{@code %xy}".
     * @param s the {@code String} 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}
     */
    @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} string using a specific
     * encoding scheme.
     * The supplied encoding is used to determine
     * what characters are represented by any consecutive sequences of the
     * form "<i>{@code %xy}".
     * <p>
     * <em>Note: The 

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