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package com.sun.mail.util;
import java.io.*;
/**
* This class implements a Q Encoder as defined by RFC 2047 for
* encoding MIME headers. It subclasses the QPEncoderStream class.
*
* @author John Mani
*/
public class QEncoderStream extends QPEncoderStream {
private String specials;
private static String WORD_SPECIALS = "=_?\"#$%&'(),.:;<>@[\\]^`{|}~";
private static String TEXT_SPECIALS = "=_?";
/**
* Create a Q encoder that encodes the specified input stream
* @param out the output stream
* @param encodingWord true if we are Q-encoding a word within a
* phrase.
*/
public QEncoderStream(OutputStream out, boolean encodingWord) {
super(out, Integer.MAX_VALUE); // MAX_VALUE is 2^31, should
// suffice (!) to indicate that
// CRLFs should not be inserted
// when encoding rfc822 headers
// a RFC822 "word" token has more restrictions than a
// RFC822 "text" token.
specials = encodingWord ? WORD_SPECIALS : TEXT_SPECIALS;
}
/**
* Encodes the specified byte to this output stream.
* @param c the byte.
* @exception IOException if an I/O error occurs.
*/
@Override
public void write(int c) throws IOException {
c = c & 0xff; // Turn off the MSB.
if (c == ' ')
output('_', false);
else if (c < 040 || c >= 0177 || specials.indexOf(c) >= 0)
// Encoding required.
output(c, true);
else // No encoding required
output(c, false);
}
/**
* Returns the length of the encoded version of this byte array.
*
* @param b the byte array
* @param encodingWord true if encoding words, false if encoding text
* @return the length
*/
public static int encodedLength(byte[] b, boolean encodingWord) {
int len = 0;
String specials = encodingWord ? WORD_SPECIALS: TEXT_SPECIALS;
for (int i = 0; i < b.length; i++) {
int c = b[i] & 0xff; // Mask off MSB
if (c < 040 || c >= 0177 || specials.indexOf(c) >= 0)
// needs encoding
len += 3; // Q-encoding is 1 -> 3 conversion
else
len++;
}
return len;
}
/**** begin TEST program ***
public static void main(String argv[]) throws Exception {
FileInputStream infile = new FileInputStream(argv[0]);
QEncoderStream encoder = new QEncoderStream(System.out);
int c;
while ((c = infile.read()) != -1)
encoder.write(c);
encoder.close();
}
*** end TEST program ***/
}