HexaEncoding


1   /**
2    * C-JDBC: Clustered JDBC.
3    * Copyright (C) 2002-2004 French National Institute For Research In Computer
4    * Science And Control (INRIA).
5    * Contact: c-jdbc@objectweb.org
6    * 
7    * This library is free software; you can redistribute it and/or modify it
8    * under the terms of the GNU Lesser General Public License as published by the
9    * Free Software Foundation; either version 2.1 of the License, or any later
10   * version.
11   * 
12   * This library is distributed in the hope that it will be useful, but WITHOUT
13   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14   * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
15   * for more details.
16   * 
17   * You should have received a copy of the GNU Lesser General Public License
18   * along with this library; if not, write to the Free Software Foundation,
19   * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
20   *
21   * Initial developer(s): Nicolas Modrzyk
22   * Contributor(s): ______________________.
23   */
24  
25  package org.objectweb.cjdbc.common.stream.encoding;
26  
27  /**
28   * This class implements Hexa encoding and decoding
29   * 
30   * @author <a HREF="mailto:Nicolas.Modrzyk@inria.fr">Nicolas Modrzyk </a>
31   * @version 1.0
32   */
33  public class HexaEncoding
34  {
35    /**
36     * Convert data into hexa
37     * 
38     * @param data to convert
39     * @return the converted string
40     */
41    public static final String   data2hex(byte[] data)
42    {
43      if (data == null)
44        return null;
45  
46      int len = data.length;
47      StringBuffer   buf = new StringBuffer  (len * 2);
48      for (int pos = 0; pos < len; pos++)
49        buf.append(toHexChar((data[pos] >>> 4) & 0x0F)).append(
50            toHexChar(data[pos] & 0x0F));
51      return buf.toString();
52    }
53  
54    /**
55     * convert hexa into data
56     * 
57     * @param str to convert
58     * @return the converted byte array
59     */
60    public static final byte[] hex2data(String   str)
61    {
62      if (str == null)
63        return new byte[0];
64  
65      int len = str.length();
66      char[] hex = str.toCharArray();
67      byte[] buf = new byte[len / 2];
68  
69      for (int pos = 0; pos < len / 2; pos++)
70        buf[pos] = (byte) (((toDataNibble(hex[2 * pos]) << 4) & 0xF0) | (toDataNibble(hex[2 * pos + 1]) & 0x0F));
71  
72      return buf;
73    }
74  
75    /**
76     * convert value to hexa value
77     * 
78     * @param i byte to convert
79     * @return hexa char
80     */
81    public static char toHexChar(int i)
82    {
83      if ((0 <= i) && (i <= 9))
84        return (char) ('0' + i);
85      else
86        return (char) ('a' + (i - 10));
87    }
88  
89    /**
90     * convert hexa char to byte value
91     * 
92     * @param c hexa character
93     * @return corresponding byte value
94     */
95    public static byte toDataNibble(char c)
96    {
97      if (('0' <= c) && (c <= '9'))
98        return (byte) ((byte) c - (byte) '0');
99      else if (('a' <= c) && (c <= 'f'))
100       return (byte) ((byte) c - (byte) 'a' + 10);
101     else if (('A' <= c) && (c <= 'F'))
102       return (byte) ((byte) c - (byte) 'A' + 10);
103     else
104       return -1;
105   }
106 }
107
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