KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > org > apache > tomcat > util > buf > HexUtils


1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one or more
3  * contributor license agreements. See the NOTICE file distributed with
4  * this work for additional information regarding copyright ownership.
5  * The ASF licenses this file to You under the Apache License, Version 2.0
6  * (the "License"); you may not use this file except in compliance with
7  * the License. You may obtain a copy of the License at
8  *
9  * http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  */
17
18 package org.apache.tomcat.util.buf;
19
20 import java.io.ByteArrayOutputStream JavaDoc;
21 import org.apache.tomcat.util.res.StringManager;
22
23 /**
24  * Library of utility methods useful in dealing with converting byte arrays
25  * to and from strings of hexadecimal digits.
26  * Code from Ajp11, from Apache's JServ.
27  *
28  * @author Craig R. McClanahan
29  */
30
31 public final class HexUtils {
32
33
34     // -------------------------------------------------------------- Constants
35
36
37     /**
38      * Table for HEX to DEC byte translation.
39      */
40     public static final int[] DEC = {
41         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
42         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
43         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
44         00, 01, 02, 03, 04, 05, 06, 07, 8, 9, -1, -1, -1, -1, -1, -1,
45         -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
46         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
47         -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
48         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
49         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
50         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
51         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
52         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
53         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
54         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
55         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
56         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
57     };
58
59
60     /**
61      * Table for DEC to HEX byte translation.
62      */
63     public static final byte[] HEX =
64     { (byte) '0', (byte) '1', (byte) '2', (byte) '3', (byte) '4', (byte) '5',
65       (byte) '6', (byte) '7', (byte) '8', (byte) '9', (byte) 'a', (byte) 'b',
66       (byte) 'c', (byte) 'd', (byte) 'e', (byte) 'f' };
67
68
69     /**
70      * The string manager for this package.
71      */
72     private static StringManager sm =
73     StringManager.getManager("org.apache.tomcat.util.buf.res");
74
75
76     // --------------------------------------------------------- Static Methods
77
78
79     /**
80      * Convert a String of hexadecimal digits into the corresponding
81      * byte array by encoding each two hexadecimal digits as a byte.
82      *
83      * @param digits Hexadecimal digits representation
84      *
85      * @exception IllegalArgumentException if an invalid hexadecimal digit
86      * is found, or the input string contains an odd number of hexadecimal
87      * digits
88      */
89     public static byte[] convert(String JavaDoc digits) {
90
91     ByteArrayOutputStream JavaDoc baos = new ByteArrayOutputStream JavaDoc();
92     for (int i = 0; i < digits.length(); i += 2) {
93         char c1 = digits.charAt(i);
94         if ((i+1) >= digits.length())
95         throw new IllegalArgumentException JavaDoc
96             (sm.getString("hexUtil.odd"));
97         char c2 = digits.charAt(i + 1);
98         byte b = 0;
99         if ((c1 >= '0') && (c1 <= '9'))
100         b += ((c1 - '0') * 16);
101         else if ((c1 >= 'a') && (c1 <= 'f'))
102         b += ((c1 - 'a' + 10) * 16);
103         else if ((c1 >= 'A') && (c1 <= 'F'))
104         b += ((c1 - 'A' + 10) * 16);
105         else
106         throw new IllegalArgumentException JavaDoc
107             (sm.getString("hexUtil.bad"));
108         if ((c2 >= '0') && (c2 <= '9'))
109         b += (c2 - '0');
110         else if ((c2 >= 'a') && (c2 <= 'f'))
111         b += (c2 - 'a' + 10);
112         else if ((c2 >= 'A') && (c2 <= 'F'))
113         b += (c2 - 'A' + 10);
114         else
115         throw new IllegalArgumentException JavaDoc
116             (sm.getString("hexUtil.bad"));
117         baos.write(b);
118     }
119     return (baos.toByteArray());
120
121     }
122
123
124     /**
125      * Convert a byte array into a printable format containing a
126      * String of hexadecimal digit characters (two per byte).
127      *
128      * @param bytes Byte array representation
129      */
130     public static String JavaDoc convert(byte bytes[]) {
131
132     StringBuffer JavaDoc sb = new StringBuffer JavaDoc(bytes.length * 2);
133     for (int i = 0; i < bytes.length; i++) {
134         sb.append(convertDigit((int) (bytes[i] >> 4)));
135         sb.append(convertDigit((int) (bytes[i] & 0x0f)));
136     }
137     return (sb.toString());
138
139     }
140
141     /**
142      * Convert 4 hex digits to an int, and return the number of converted
143      * bytes.
144      *
145      * @param hex Byte array containing exactly four hexadecimal digits
146      *
147      * @exception IllegalArgumentException if an invalid hexadecimal digit
148      * is included
149      */
150     public static int convert2Int( byte[] hex ) {
151     // Code from Ajp11, from Apache's JServ
152
153     // assert b.length==4
154 // assert valid data
155 int len;
156     if(hex.length < 4 ) return 0;
157     if( DEC[hex[0]]<0 )
158         throw new IllegalArgumentException JavaDoc(sm.getString("hexUtil.bad"));
159     len = DEC[hex[0]];
160     len = len << 4;
161     if( DEC[hex[1]]<0 )
162         throw new IllegalArgumentException JavaDoc(sm.getString("hexUtil.bad"));
163     len += DEC[hex[1]];
164     len = len << 4;
165     if( DEC[hex[2]]<0 )
166         throw new IllegalArgumentException JavaDoc(sm.getString("hexUtil.bad"));
167     len += DEC[hex[2]];
168     len = len << 4;
169     if( DEC[hex[3]]<0 )
170         throw new IllegalArgumentException JavaDoc(sm.getString("hexUtil.bad"));
171     len += DEC[hex[3]];
172     return len;
173     }
174
175
176
177     /**
178      * [Private] Convert the specified value (0 .. 15) to the corresponding
179      * hexadecimal digit.
180      *
181      * @param value Value to be converted
182      */
183     private static char convertDigit(int value) {
184
185     value &= 0x0f;
186     if (value >= 10)
187         return ((char) (value - 10 + 'a'));
188     else
189         return ((char) (value + '0'));
190
191     }
192
193
194 }
195
Popular Tags