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Java > Open Source Codes > com > mchange > lang > ByteUtils


1 /*
2  * Distributed as part of c3p0 v.0.9.1
3  *
4  * Copyright (C) 2005 Machinery For Change, Inc.
5  *
6  * Author: Steve Waldman <swaldman@mchange.com>
7  *
8  * This library is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU Lesser General Public License version 2.1, as
10  * published by the Free Software Foundation.
11  *
12  * This software is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15  * GNU Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public License
18  * along with this software; see the file LICENSE. If not, write to the
19  * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
20  * Boston, MA 02111-1307, USA.
21  */
22
23
24 package com.mchange.lang;
25
26 import java.io.StringReader JavaDoc;
27 import java.io.StringWriter JavaDoc;
28 import java.io.IOException JavaDoc;
29
30 public final class ByteUtils
31 {
32   public final static short UNSIGNED_MAX_VALUE = (Byte.MAX_VALUE * 2) + 1;
33
34   public static short toUnsigned(byte b)
35     {return (short) (b < 0 ? (UNSIGNED_MAX_VALUE + 1) + b : b);}
36
37   public static String JavaDoc toHexAscii(byte b)
38     {
39       StringWriter JavaDoc sw = new StringWriter JavaDoc(2);
40       addHexAscii(b, sw);
41       return sw.toString();
42     }
43
44   public static String JavaDoc toHexAscii(byte[] bytes)
45     {
46       int len = bytes.length;
47       StringWriter JavaDoc sw = new StringWriter JavaDoc(len * 2);
48       for (int i = 0; i < len; ++i)
49     addHexAscii(bytes[i], sw);
50       return sw.toString();
51     }
52
53   public static byte[] fromHexAscii(String JavaDoc s) throws NumberFormatException JavaDoc
54     {
55       try
56     {
57       int len = s.length();
58       if ((len % 2) != 0)
59         throw new NumberFormatException JavaDoc("Hex ascii must be exactly two digits per byte.");
60       
61       int out_len = len / 2;
62       byte[] out = new byte[out_len];
63       int i = 0;
64       StringReader JavaDoc sr = new StringReader JavaDoc(s);
65       while (i < out_len)
66         {
67           int val = (16 * fromHexDigit(sr.read())) + fromHexDigit(sr.read());
68           out[i++] = (byte) val;
69         }
70       return out;
71     }
72       catch (IOException JavaDoc e)
73     {throw new InternalError JavaDoc("IOException reading from StringReader?!?!");}
74     }
75
76   static void addHexAscii(byte b, StringWriter JavaDoc sw)
77     {
78       short ub = toUnsigned(b);
79       int h1 = ub / 16;
80       int h2 = ub % 16;
81       sw.write(toHexDigit(h1));
82       sw.write(toHexDigit(h2));
83     }
84
85   private static int fromHexDigit(int c) throws NumberFormatException JavaDoc
86     {
87       if (c >= 0x30 && c < 0x3A)
88     return c - 0x30;
89       else if (c >= 0x41 && c < 0x47)
90     return c - 0x37;
91       else if (c >= 0x61 && c < 0x67)
92     return c - 0x57;
93       else
94     throw new NumberFormatException JavaDoc('\'' + c + "' is not a valid hexadecimal digit.");
95     }
96
97   /* note: we do no arg. checking, because */
98   /* we only ever call this from addHexAscii() */
99   /* above, and we are sure the args are okay */
100   private static char toHexDigit(int h)
101     {
102     char out;
103     if (h <= 9) out = (char) (h + 0x30);
104     else out = (char) (h + 0x37);
105     //System.err.println(h + ": " + out);
106 return out;
107     }
108
109   private ByteUtils()
110     {}
111 }
112
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