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/*
* Base64OutputStream.java
* Copyright (C) 2002 The Free Software Foundation
*
* This file is part of GNU JavaMail, a library.
*
* GNU JavaMail is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* GNU JavaMail 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 for more details.
*
* You should have received a copy of the GNU General Public License
* along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* As a special exception, if you link this library with other files to
* produce an executable, this library does not by itself cause the
* resulting executable to be covered by the GNU General Public License.
* This exception does not however invalidate any other reasons why the
* executable file might be covered by the GNU General Public License.
*/
package gnu.mail.util;
import java.io.*;
/**
* A Base64 content transfer encoding filter stream.
* <p>
* From RFC 2045, section 6.8:
* <p>
* The Base64 Content-Transfer-Encoding is designed to represent
* arbitrary sequences of octets in a form that need not be humanly
* readable. The encoding and decoding algorithms are simple, but the
* encoded data are consistently only about 33 percent larger than the
* unencoded data.
*
* @author <a href="mailto:dog@gnu.org">Chris Burdess</a>
*/
public class Base64OutputStream
extends FilterOutputStream
{
private byte buffer[];
private int buflen;
private int count;
private int lineLength;
private static final char src[] =
{
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd',
'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x',
'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', '+', '/'
};
private static final int LF = 10, CR = 13, EQ = 61;
/**
* Default constructor.
* This constructs a Base64OutputStream with a line length of 76.
*/
public Base64OutputStream(OutputStream out)
{
this(out, 76);
}
/**
* Constructor.
* @param out the underlying output stream to encode
* @param lineLength the line length
*/
public Base64OutputStream(OutputStream out, int lineLength)
{
super(out);
buffer = new byte[3];
this.lineLength = lineLength;
}
/**
* Writes the specified byte to this output stream.
*/
public void write(int c)
throws IOException
{
buffer[buflen++] = (byte)c;
if (buflen==3) {
encode();
buflen = 0;
}
}
/**
* Writes <code>b.length</code> bytes from the specified byte array
* to this output stream.
*/
public void write(byte b[])
throws IOException
{
write(b, 0, b.length);
}
/**
* Writes <code>len</code> bytes from the specified byte array
* starting at offset <code>off</code> to this output stream.
*/
public void write(byte b[], int off, int len)
throws IOException
{
for (int i=0; i<len; i++)
write(b[off+i]);
}
/**
* Flushes this output stream and forces any buffered output bytes to be
* written out.
*/
public void flush()
throws IOException
{
if (buflen>0) {
encode();
buflen = 0;
}
out.flush();
}
/**
* Closes this output stream and releases any system resources
* associated with this stream.
*/
public void close()
throws IOException
{
flush();
out.close();
}
private void encode()
throws IOException
{
if ((count+4)>lineLength)
{
out.write(CR);
out.write(LF);
count = 0;
}
if (buflen==1)
{
byte b = buffer[0];
int i = 0;
boolean flag = false;
out.write(src[b>>>2 & 0x3f]);
out.write(src[(b<<4 & 0x30) + (i>>>4 & 0xf)]);
out.write(EQ);
out.write(EQ);
}
else if (buflen==2)
{
byte b1 = buffer[0], b2 = buffer[1];
int i = 0;
out.write(src[b1>>>2 & 0x3f]);
out.write(src[(b1<<4 & 0x30) + (b2>>>4 & 0xf)]);
out.write(src[(b2<<2 & 0x3c) + (i>>>6 & 0x3)]);
out.write(EQ);
}
else
{
byte b1 = buffer[0], b2 = buffer[1], b3 = buffer[2];
out.write(src[b1>>>2 & 0x3f]);
out.write(src[(b1<<4 & 0x30) + (b2>>>4 & 0xf)]);
out.write(src[(b2<<2 & 0x3c) + (b3>>>6 & 0x3)]);
out.write(src[b3 & 0x3f]);
}
count += 4;
}
}
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