1 /* 2 * Copyright (c) 1995, 1997, Oracle and/or its affiliates. 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. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * 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 } 113
