242 lines
7.0 KiB
Java
242 lines
7.0 KiB
Java
/* ====================================================================
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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==================================================================== */
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package org.apache.poi.poifs.poibrowser;
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import java.io.BufferedReader;
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import java.io.IOException;
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import java.io.InputStreamReader;
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import org.apache.poi.hpsf.ClassID;
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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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*/
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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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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>Converts a short value (16-bit) into its hexadecimal
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* notation.</p>
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*/
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public static String hexEncode(final short s)
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{
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StringBuffer sb = new StringBuffer(4);
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sb.append((char) hexval[(s & 0xF000) >> 12]);
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sb.append((char) hexval[(s & 0x0F00) >> 8]);
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sb.append((char) hexval[(s & 0x00F0) >> 4]);
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sb.append((char) hexval[(s & 0x000F) >> 0]);
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return sb.toString();
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}
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/**
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* <p>Converts an int value (32-bit) into its hexadecimal
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* notation.</p>
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*/
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public static String hexEncode(final int i)
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{
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StringBuffer sb = new StringBuffer(8);
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sb.append((char) hexval[(i & 0xF0000000) >> 28]);
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sb.append((char) hexval[(i & 0x0F000000) >> 24]);
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sb.append((char) hexval[(i & 0x00F00000) >> 20]);
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sb.append((char) hexval[(i & 0x000F0000) >> 16]);
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sb.append((char) hexval[(i & 0x0000F000) >> 12]);
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sb.append((char) hexval[(i & 0x00000F00) >> 8]);
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sb.append((char) hexval[(i & 0x000000F0) >> 4]);
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sb.append((char) hexval[(i & 0x0000000F) >> 0]);
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return sb.toString();
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}
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/**
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* <p>Converts a long value (64-bit) into its hexadecimal
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* notation.</p>
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*/
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public static String hexEncode(final long l)
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{
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StringBuffer sb = new StringBuffer(16);
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sb.append(hexEncode((int) (l & 0xFFFFFFFF00000000L) >> 32));
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sb.append(hexEncode((int) (l & 0x00000000FFFFFFFFL) >> 0));
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return sb.toString();
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}
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/**
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* <p>Converts a class ID into its hexadecimal notation.</p>
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*/
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public static String hexEncode(final ClassID classID)
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{
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return hexEncode(classID.getBytes());
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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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* @throws 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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