/*
* Copyright (c) 1995, 1997, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package sun.misc;
import java.io.OutputStream;
import java.io.InputStream;
import java.io.PrintStream;
import java.io.IOException;
This class implements a BASE64 Character encoder as specified in RFC1521.
This RFC is part of the MIME specification as published by the Internet
Engineering Task Force (IETF). Unlike some other encoding schemes there
is nothing in this encoding that indicates
where a buffer starts or ends.
This means that the encoded text will simply start with the first line
of encoded text and end with the last line of encoded text.
Author: Chuck McManis See Also:
/**
* This class implements a BASE64 Character encoder as specified in RFC1521.
* This RFC is part of the MIME specification as published by the Internet
* Engineering Task Force (IETF). Unlike some other encoding schemes there
* is nothing in this encoding that indicates
* where a buffer starts or ends.
*
* This means that the encoded text will simply start with the first line
* of encoded text and end with the last line of encoded text.
*
* @author Chuck McManis
* @see CharacterEncoder
* @see BASE64Decoder
*/
public class BASE64Encoder extends CharacterEncoder {
this class encodes three bytes per atom. /** this class encodes three bytes per atom. */
protected int bytesPerAtom() {
return (3);
}
this class encodes 57 bytes per line. This results in a maximum
of 57/3 * 4 or 76 characters per output line. Not counting the
line termination.
/**
* this class encodes 57 bytes per line. This results in a maximum
* of 57/3 * 4 or 76 characters per output line. Not counting the
* line termination.
*/
protected int bytesPerLine() {
return (57);
}
This array maps the characters to their 6 bit values /** This array maps the characters to their 6 bit values */
private final static char pem_array[] = {
// 0 1 2 3 4 5 6 7
'A','B','C','D','E','F','G','H', // 0
'I','J','K','L','M','N','O','P', // 1
'Q','R','S','T','U','V','W','X', // 2
'Y','Z','a','b','c','d','e','f', // 3
'g','h','i','j','k','l','m','n', // 4
'o','p','q','r','s','t','u','v', // 5
'w','x','y','z','0','1','2','3', // 6
'4','5','6','7','8','9','+','/' // 7
};
encodeAtom - Take three bytes of input and encode it as 4
printable characters. Note that if the length in len is less
than three is encodes either one or two '=' signs to indicate
padding characters.
/**
* encodeAtom - Take three bytes of input and encode it as 4
* printable characters. Note that if the length in len is less
* than three is encodes either one or two '=' signs to indicate
* padding characters.
*/
protected void encodeAtom(OutputStream outStream, byte data[], int offset, int len)
throws IOException {
byte a, b, c;
if (len == 1) {
a = data[offset];
b = 0;
c = 0;
outStream.write(pem_array[(a >>> 2) & 0x3F]);
outStream.write(pem_array[((a << 4) & 0x30) + ((b >>> 4) & 0xf)]);
outStream.write('=');
outStream.write('=');
} else if (len == 2) {
a = data[offset];
b = data[offset+1];
c = 0;
outStream.write(pem_array[(a >>> 2) & 0x3F]);
outStream.write(pem_array[((a << 4) & 0x30) + ((b >>> 4) & 0xf)]);
outStream.write(pem_array[((b << 2) & 0x3c) + ((c >>> 6) & 0x3)]);
outStream.write('=');
} else {
a = data[offset];
b = data[offset+1];
c = data[offset+2];
outStream.write(pem_array[(a >>> 2) & 0x3F]);
outStream.write(pem_array[((a << 4) & 0x30) + ((b >>> 4) & 0xf)]);
outStream.write(pem_array[((b << 2) & 0x3c) + ((c >>> 6) & 0x3)]);
outStream.write(pem_array[c & 0x3F]);
}
}
}