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package com.sun.mail.util;
import java.io.*;
/**
* This class implements a Quoted Printable Encoder. It is implemented as
* a FilterOutputStream, so one can just wrap this class around
* any output stream and write bytes into this filter. The Encoding
* is done as the bytes are written out.
*
* @author John Mani
*/
public class QPEncoderStream extends FilterOutputStream {
private int count = 0; // number of bytes that have been output
private int bytesPerLine; // number of bytes per line
private boolean gotSpace = false;
private boolean gotCR = false;
/**
* Create a QP encoder that encodes the specified input stream
* @param out the output stream
* @param bytesPerLine the number of bytes per line. The encoder
* inserts a CRLF sequence after this many number
* of bytes.
*/
public QPEncoderStream(OutputStream out, int bytesPerLine) {
super(out);
// Subtract 1 to account for the '=' in the soft-return
// at the end of a line
this.bytesPerLine = bytesPerLine - 1;
}
/**
* Create a QP encoder that encodes the specified input stream.
* Inserts the CRLF sequence after outputting 76 bytes.
* @param out the output stream
*/
public QPEncoderStream(OutputStream out) {
this(out, 76);
}
/**
* Encodes <code>len</code> bytes from the specified
* <code>byte</code> array starting at offset <code>off</code> to
* this output stream.
*
* @param b the data.
* @param off the start offset in the data.
* @param len the number of bytes to write.
* @exception IOException if an I/O error occurs.
*/
public void write(byte[] b, int off, int len) throws IOException {
for (int i = 0; i < len; i++)
write(b[off + i]);
}
/**
* Encodes <code>b.length</code> bytes to this output stream.
* @param b the data to be written.
* @exception IOException if an I/O error occurs.
*/
public void write(byte[] b) throws IOException {
write(b, 0, b.length);
}
/**
* Encodes the specified <code>byte</code> to this output stream.
* @param c the <code>byte</code>.
* @exception IOException if an I/O error occurs.
*/
public void write(int c) throws IOException {
c = c & 0xff; // Turn off the MSB.
if (gotSpace) { // previous character was <SPACE>
if (c == '\r' || c == '\n')
// if CR/LF, we need to encode the <SPACE> char
output(' ', true);
else // no encoding required, just output the char
output(' ', false);
gotSpace = false;
}
if (c == '\r') {
gotCR = true;
outputCRLF();
} else {
if (c == '\n') {
if (gotCR)
// This is a CRLF sequence, we already output the
// corresponding CRLF when we got the CR, so ignore this
;
else
outputCRLF();
} else if (c == ' ') {
gotSpace = true;
} else if (c < 040 || c >= 0177 || c == '=')
// Encoding required.
output(c, true);
else // No encoding required
output(c, false);
// whatever it was, it wasn't a CR
gotCR = false;
}
}
/**
* Flushes this output stream and forces any buffered output bytes
* to be encoded out to the stream.
* @exception IOException if an I/O error occurs.
*/
public void flush() throws IOException {
out.flush();
}
/**
* Forces any buffered output bytes to be encoded out to the stream
* and closes this output stream
*/
public void close() throws IOException {
if (gotSpace) {
output(' ', true);
gotSpace = false;
}
out.close();
}
private void outputCRLF() throws IOException {
out.write('\r');
out.write('\n');
count = 0;
}
// The encoding table
private final static char hex[] = {
'0','1', '2', '3', '4', '5', '6', '7',
'8','9', 'A', 'B', 'C', 'D', 'E', 'F'
};
protected void output(int c, boolean encode) throws IOException {
if (encode) {
if ((count += 3) > bytesPerLine) {
out.write('=');
out.write('\r');
out.write('\n');
count = 3; // set the next line's length
}
out.write('=');
out.write(hex[c >> 4]);
out.write(hex[c & 0xf]);
} else {
if (++count > bytesPerLine) {
out.write('=');
out.write('\r');
out.write('\n');
count = 1; // set the next line's length
}
out.write(c);
}
}
/**** begin TEST program ***
public static void main(String argv[]) throws Exception {
FileInputStream infile = new FileInputStream(argv[0]);
QPEncoderStream encoder = new QPEncoderStream(System.out);
int c;
while ((c = infile.read()) != -1)
encoder.write(c);
encoder.close();
}
*** end TEST program ***/
}
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