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/*
* 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 net.sourceforge.jnlp.util.replacements;
import java.io.OutputStream;
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 CharacterEncoder
* @see BASE64Decoder
*/
public class BASE64Encoder extends CharacterEncoder {
/** 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.
*/
protected int bytesPerLine() {
return (57);
}
/** 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.
*/
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]);
}
}
}
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