226 lines
7.3 KiB
Java
226 lines
7.3 KiB
Java
/* ====================================================================
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* The Apache Software License, Version 1.1
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*
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* Copyright (c) 2000 The Apache Software Foundation. All rights
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* reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* 3. The end-user documentation included with the redistribution,
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* if any, must include the following acknowledgment:
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* "This product includes software developed by the
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* Apache Software Foundation (http://www.apache.org/)."
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* Alternately, this acknowledgment may appear in the software itself,
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* if and wherever such third-party acknowledgments normally appear.
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*
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* 4. The names "Apache" and "Apache Software Foundation" must
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* not be used to endorse or promote products derived from this
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* software without prior written permission. For written
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* permission, please contact apache@apache.org.
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*
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* 5. Products derived from this software may not be called "Apache",
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* nor may "Apache" appear in their name, without prior written
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* permission of the Apache Software Foundation.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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* ====================================================================
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*
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* This software consists of voluntary contributions made by many
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* individuals on behalf of the Apache Software Foundation. For more
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* information on the Apache Software Foundation, please see
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* <http://www.apache.org/>.
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*
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* Portions of this software are based upon public domain software
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* originally written at the National Center for Supercomputing Applications,
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* University of Illinois, Urbana-Champaign.
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*/
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package org.apache.poi.contrib.poibrowser;
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import java.io.*;
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import java.util.*;
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/**
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* <p>Provides utility methods for encoding and decoding hexadecimal
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* data.</p>
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*
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* @author Rainer Klute (klute@rainer-klute.de) - with portions from Tomcat
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* @version $Id$
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* @since 2002-01-24
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*/
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public class Codec
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{
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/**
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* <p>The nibbles' hexadecimal values. A nibble is a half byte.</p>
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*/
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protected static final byte hexval[] =
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{(byte) '0', (byte) '1', (byte) '2', (byte) '3',
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(byte) '4', (byte) '5', (byte) '6', (byte) '7',
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(byte) '8', (byte) '9', (byte) 'A', (byte) 'B',
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(byte) 'C', (byte) 'D', (byte) 'E', (byte) 'F'};
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/**
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* <p>Converts a string into its hexadecimal notation.</p>
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*
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* <p><strong>FIXME:</strong> If this method is called frequently,
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* it should directly implement the algorithm in the called method
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* in order to avoid creating a string instance.</p>
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*/
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public static String hexEncode(final String s)
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{
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return hexEncode(s.getBytes());
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}
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/**
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* <p>Converts a byte array into its hexadecimal notation.</p>
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*/
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public static String hexEncode(final byte[] s)
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{
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return hexEncode(s, 0, s.length);
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}
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/**
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* <p>Converts a part of a byte array into its hexadecimal
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* notation.</p>
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*/
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public static String hexEncode(final byte[] s, final int offset,
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final int length)
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{
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StringBuffer b = new StringBuffer(length * 2);
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for (int i = offset; i < offset + length; i++)
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{
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int c = s[i];
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b.append((char) hexval[(c & 0xF0) >> 4]);
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b.append((char) hexval[(c & 0x0F) >> 0]);
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}
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return b.toString();
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}
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/**
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* <p>Converts a single byte into its hexadecimal notation.</p>
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*/
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public static String hexEncode(final byte b)
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{
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StringBuffer sb = new StringBuffer(2);
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sb.append((char) hexval[(b & 0xF0) >> 4]);
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sb.append((char) hexval[(b & 0x0F) >> 0]);
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return sb.toString();
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}
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/**
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* <p>Decodes the hexadecimal representation of a sequence of
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* bytes into a byte array. Each character in the string
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* represents a nibble (half byte) and must be one of the
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* characters '0'-'9', 'A'-'F' or 'a'-'f'.</p>
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*
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* @param s The string to be decoded
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*
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* @return The bytes
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*
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* @throw IllegalArgumentException if the string does not contain
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* a valid representation of a byte sequence.
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*/
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public static byte[] hexDecode(final String s)
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{
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final int length = s.length();
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/* The string to be converted must have an even number of
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characters. */
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if (length % 2 == 1)
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throw new IllegalArgumentException
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("String has odd length " + length);
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byte[] b = new byte[length / 2];
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char[] c = new char[length];
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s.toUpperCase().getChars(0, length, c, 0);
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for (int i = 0; i < length; i += 2)
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b[i/2] = (byte) (decodeNibble(c[i]) << 4 & 0xF0 |
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decodeNibble(c[i+1]) & 0x0F);
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return b;
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}
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/**
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* <p>Decodes a nibble.</p>
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*
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* @param c A character in the range '0'-'9' or 'A'-'F'. Lower
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* case is not supported here.
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*
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* @return The decoded nibble in the range 0-15
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*
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* @throws IllegalArgumentException if <em>c</em> is not a
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* permitted character
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*/
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protected static byte decodeNibble(final char c)
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{
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for (byte i = 0; i < hexval.length; i++)
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if ((byte) c == hexval[i])
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return i;
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throw new IllegalArgumentException("\"" + c + "\"" +
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" does not represent a nibble.");
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}
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/**
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* <p>For testing.</p>
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*/
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public static void main(final String args[])
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throws IOException
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{
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final BufferedReader in =
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new BufferedReader(new InputStreamReader(System.in));
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String s;
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do
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{
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s = in.readLine();
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if (s != null)
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{
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String bytes = hexEncode(s);
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System.out.print("Hex encoded (String): ");
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System.out.println(bytes);
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System.out.print("Hex encoded (byte[]): ");
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System.out.println(hexEncode(s.getBytes()));
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System.out.print("Re-decoded (byte[]): ");
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System.out.println(new String(hexDecode(bytes)));
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}
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}
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while (s != null);
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}
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}
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