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Java > Open Source Codes > org > apache > xerces > impl > dv > util > HexBin


1 /*
2  * Copyright 1999-2002,2004 The Apache Software Foundation.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16
17 package org.apache.xerces.impl.dv.util;
18
19 /**
20  * format validation
21  *
22  * This class encodes/decodes hexadecimal data
23  *
24  * @xerces.internal
25  *
26  * @author Jeffrey Rodriguez
27  * @version $Id: HexBin.java,v 1.13 2004/10/14 15:20:18 mrglavas Exp $
28  */
29 public final class HexBin {
30     static private final int BASELENGTH = 128;
31     static private final int LOOKUPLENGTH = 16;
32     static final private byte [] hexNumberTable = new byte[BASELENGTH];
33     static final private char [] lookUpHexAlphabet = new char[LOOKUPLENGTH];
34
35
36     static {
37         for (int i = 0; i < BASELENGTH; i++ ) {
38             hexNumberTable[i] = -1;
39         }
40         for ( int i = '9'; i >= '0'; i--) {
41             hexNumberTable[i] = (byte) (i-'0');
42         }
43         for ( int i = 'F'; i>= 'A'; i--) {
44             hexNumberTable[i] = (byte) ( i-'A' + 10 );
45         }
46         for ( int i = 'f'; i>= 'a'; i--) {
47            hexNumberTable[i] = (byte) ( i-'a' + 10 );
48         }
49
50         for(int i = 0; i<10; i++ ) {
51             lookUpHexAlphabet[i] = (char)('0'+i);
52         }
53         for(int i = 10; i<=15; i++ ) {
54             lookUpHexAlphabet[i] = (char)('A'+i -10);
55         }
56     }
57
58     /**
59      * Encode a byte array to hex string
60      *
61      * @param binaryData array of byte to encode
62      * @return return encoded string
63      */
64     static public String JavaDoc encode(byte[] binaryData) {
65         if (binaryData == null)
66             return null;
67         int lengthData = binaryData.length;
68         int lengthEncode = lengthData * 2;
69         char[] encodedData = new char[lengthEncode];
70         int temp;
71         for (int i = 0; i < lengthData; i++) {
72             temp = binaryData[i];
73             if (temp < 0)
74                 temp += 256;
75             encodedData[i*2] = lookUpHexAlphabet[temp >> 4];
76             encodedData[i*2+1] = lookUpHexAlphabet[temp & 0xf];
77         }
78         return new String JavaDoc(encodedData);
79     }
80
81     /**
82      * Decode hex string to a byte array
83      *
84      * @param encoded encoded string
85      * @return return array of byte to encode
86      */
87     static public byte[] decode(String JavaDoc encoded) {
88         if (encoded == null)
89             return null;
90         int lengthData = encoded.length();
91         if (lengthData % 2 != 0)
92             return null;
93
94         char[] binaryData = encoded.toCharArray();
95         int lengthDecode = lengthData / 2;
96         byte[] decodedData = new byte[lengthDecode];
97         byte temp1, temp2;
98         char tempChar;
99         for( int i = 0; i<lengthDecode; i++ ){
100             tempChar = binaryData[i*2];
101             temp1 = (tempChar < BASELENGTH) ? hexNumberTable[tempChar] : -1;
102             if (temp1 == -1)
103                 return null;
104             tempChar = binaryData[i*2+1];
105             temp2 = (tempChar < BASELENGTH) ? hexNumberTable[tempChar] : -1;
106             if (temp2 == -1)
107                 return null;
108             decodedData[i] = (byte)((temp1 << 4) | temp2);
109         }
110         return decodedData;
111     }
112 }
113
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