Java example source code file (QEncoderStream.java)

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Java - Java tags/keywords

ioexception, mask, max_value, msb, q\-encoding, qencoderstream, qpencoderstream, string, text_specials, turn, word_specials

The QEncoderStream.java Java example source code

/*
 * Copyright (c) 1997, 2012, 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.
 */

/*
 * @(#)QEncoderStream.java    1.4 02/03/27
 */



package com.sun.xml.internal.messaging.saaj.packaging.mime.util;

import java.io.IOException;
import java.io.OutputStream;

/**
 * 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 <code>byte to this output stream.
     * @param      c   the <code>byte.
     * @exception  IOException  if an I/O error occurs.
     */
    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.
     */
    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 ***/
}