J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 1995-1997 Sun Microsystems, Inc. All Rights Reserved. |
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 | * |
| 5 | * This code is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License version 2 only, as |
| 7 | * published by the Free Software Foundation. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun in the LICENSE file that accompanied this code. |
| 10 | * |
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 14 | * version 2 for more details (a copy is included in the LICENSE file that |
| 15 | * accompanied this code). |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License version |
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 20 | * |
| 21 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | package sun.misc; |
| 26 | |
| 27 | import java.io.OutputStream; |
| 28 | import java.io.InputStream; |
| 29 | import java.io.PrintStream; |
| 30 | import java.io.IOException; |
| 31 | |
| 32 | /** |
| 33 | * This class implements a BASE64 Character encoder as specified in RFC1521. |
| 34 | * This RFC is part of the MIME specification as published by the Internet |
| 35 | * Engineering Task Force (IETF). Unlike some other encoding schemes there |
| 36 | * is nothing in this encoding that indicates |
| 37 | * where a buffer starts or ends. |
| 38 | * |
| 39 | * This means that the encoded text will simply start with the first line |
| 40 | * of encoded text and end with the last line of encoded text. |
| 41 | * |
| 42 | * @author Chuck McManis |
| 43 | * @see CharacterEncoder |
| 44 | * @see BASE64Decoder |
| 45 | */ |
| 46 | |
| 47 | public class BASE64Encoder extends CharacterEncoder { |
| 48 | |
| 49 | /** this class encodes three bytes per atom. */ |
| 50 | protected int bytesPerAtom() { |
| 51 | return (3); |
| 52 | } |
| 53 | |
| 54 | /** |
| 55 | * this class encodes 57 bytes per line. This results in a maximum |
| 56 | * of 57/3 * 4 or 76 characters per output line. Not counting the |
| 57 | * line termination. |
| 58 | */ |
| 59 | protected int bytesPerLine() { |
| 60 | return (57); |
| 61 | } |
| 62 | |
| 63 | /** This array maps the characters to their 6 bit values */ |
| 64 | private final static char pem_array[] = { |
| 65 | // 0 1 2 3 4 5 6 7 |
| 66 | 'A','B','C','D','E','F','G','H', // 0 |
| 67 | 'I','J','K','L','M','N','O','P', // 1 |
| 68 | 'Q','R','S','T','U','V','W','X', // 2 |
| 69 | 'Y','Z','a','b','c','d','e','f', // 3 |
| 70 | 'g','h','i','j','k','l','m','n', // 4 |
| 71 | 'o','p','q','r','s','t','u','v', // 5 |
| 72 | 'w','x','y','z','0','1','2','3', // 6 |
| 73 | '4','5','6','7','8','9','+','/' // 7 |
| 74 | }; |
| 75 | |
| 76 | /** |
| 77 | * encodeAtom - Take three bytes of input and encode it as 4 |
| 78 | * printable characters. Note that if the length in len is less |
| 79 | * than three is encodes either one or two '=' signs to indicate |
| 80 | * padding characters. |
| 81 | */ |
| 82 | protected void encodeAtom(OutputStream outStream, byte data[], int offset, int len) |
| 83 | throws IOException { |
| 84 | byte a, b, c; |
| 85 | |
| 86 | if (len == 1) { |
| 87 | a = data[offset]; |
| 88 | b = 0; |
| 89 | c = 0; |
| 90 | outStream.write(pem_array[(a >>> 2) & 0x3F]); |
| 91 | outStream.write(pem_array[((a << 4) & 0x30) + ((b >>> 4) & 0xf)]); |
| 92 | outStream.write('='); |
| 93 | outStream.write('='); |
| 94 | } else if (len == 2) { |
| 95 | a = data[offset]; |
| 96 | b = data[offset+1]; |
| 97 | c = 0; |
| 98 | outStream.write(pem_array[(a >>> 2) & 0x3F]); |
| 99 | outStream.write(pem_array[((a << 4) & 0x30) + ((b >>> 4) & 0xf)]); |
| 100 | outStream.write(pem_array[((b << 2) & 0x3c) + ((c >>> 6) & 0x3)]); |
| 101 | outStream.write('='); |
| 102 | } else { |
| 103 | a = data[offset]; |
| 104 | b = data[offset+1]; |
| 105 | c = data[offset+2]; |
| 106 | outStream.write(pem_array[(a >>> 2) & 0x3F]); |
| 107 | outStream.write(pem_array[((a << 4) & 0x30) + ((b >>> 4) & 0xf)]); |
| 108 | outStream.write(pem_array[((b << 2) & 0x3c) + ((c >>> 6) & 0x3)]); |
| 109 | outStream.write(pem_array[c & 0x3F]); |
| 110 | } |
| 111 | } |
| 112 | } |