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Java > Open Source Codes > com > quadcap > io > Base64InputStream


1 package com.quadcap.io;
2
3 /* Copyright 1997 - 2003 Quadcap Software. All rights reserved.
4  *
5  * This software is distributed under the Quadcap Free Software License.
6  * This software may be used or modified for any purpose, personal or
7  * commercial. Open Source redistributions are permitted. Commercial
8  * redistribution of larger works derived from, or works which bundle
9  * this software requires a "Commercial Redistribution License"; see
10  * http://www.quadcap.com/purchase.
11  *
12  * Redistributions qualify as "Open Source" under one of the following terms:
13  *
14  * Redistributions are made at no charge beyond the reasonable cost of
15  * materials and delivery.
16  *
17  * Redistributions are accompanied by a copy of the Source Code or by an
18  * irrevocable offer to provide a copy of the Source Code for up to three
19  * years at the cost of materials and delivery. Such redistributions
20  * must allow further use, modification, and redistribution of the Source
21  * Code under substantially the same terms as this license.
22  *
23  * Redistributions of source code must retain the copyright notices as they
24  * appear in each source code file, these license terms, and the
25  * disclaimer/limitation of liability set forth as paragraph 6 below.
26  *
27  * Redistributions in binary form must reproduce this Copyright Notice,
28  * these license terms, and the disclaimer/limitation of liability set
29  * forth as paragraph 6 below, in the documentation and/or other materials
30  * provided with the distribution.
31  *
32  * The Software is provided on an "AS IS" basis. No warranty is
33  * provided that the Software is free of defects, or fit for a
34  * particular purpose.
35  *
36  * Limitation of Liability. Quadcap Software shall not be liable
37  * for any damages suffered by the Licensee or any third party resulting
38  * from use of the Software.
39  */

40
41 import java.io.InputStream JavaDoc;
42 import java.io.IOException JavaDoc;
43
44 /**
45  *
46  *
47  * @author Stan Bailes
48  */

49 public class Base64InputStream extends InputStream JavaDoc {
50     InputStream JavaDoc in;
51     int accum = 0;
52     int cnt = -1;
53     boolean eof = false;
54
55     static int[] base64Map = new int[256];
56     static {
57     byte[] b = Base64OutputStream.base64;
58     for (int i = 0; i < base64Map.length; i++) base64Map[i] = -1;
59     for (int i = 0; i < b.length; i++) {
60         base64Map[b[i]] = i;
61     }
62     base64Map['='] = 0;
63     }
64
65     public Base64InputStream(InputStream JavaDoc in) {
66     this.in = in;
67     }
68
69     final int readChar() throws IOException JavaDoc {
70     int c = eof ? -1 : in.read();
71     while (c == '\r' || c == '\n') c = in.read();
72     eof = c < 0;
73     return c;
74     }
75
76     public int read() throws IOException JavaDoc {
77     if (eof) return -1;
78     if (cnt < 0) {
79         int c1 = readChar();
80         int c2 = readChar();
81         int c3 = readChar();
82         int c4 = readChar();
83 // System.out.println("[" + (char)c1 + "] [" + (char)c2 + "] [" + (char)c3 +
84
// "] [" + (char)c4 + "]");
85
if (eof) return -1;
86
87         int b1 = base64Map[c1];
88         int b2 = base64Map[c2];
89         int b3 = base64Map[c3];
90         int b4 = base64Map[c4];
91
92 // System.out.println("(" + b1 + ") (" + b2 + ") (" + b3 + ") (" + b4 + ")");
93
if (b1 < 0 || b2 < 0 || b3 < 0 || b4 < 0) {
94         throw new IOException JavaDoc("Bad base64 character");
95         }
96         accum = (b1 << 18) | (b2 << 12) | (b3 << 6) | b4;
97 // System.out.println(Integer.toHexString(accum));
98

99         if (c3 == '=') {
100         cnt = 0;
101         accum >>= 16;
102         } else if (c4 == '=') {
103         cnt = 8;
104         accum >>= 8;
105         } else {
106         cnt = 16;
107         }
108         
109     }
110     int ret = (accum >> cnt) & 0xff;
111     cnt -= 8;
112     return ret;
113     }
114
115     public void close() throws IOException JavaDoc {
116     in.close();
117     }
118 }
119
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