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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
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/*
 * @(#)QDecoderStream.java    1.5 02/03/27
 */



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

import java.io.IOException;
import java.io.InputStream;


This class implements a Q Decoder as defined in RFC 2047
for decoding MIME headers. It subclasses the QPDecoderStream class.

Author:John Mani
/**
 * This class implements a Q Decoder as defined in RFC 2047
 * for decoding MIME headers. It subclasses the QPDecoderStream class.
 *
 * @author John Mani
 */

public class QDecoderStream extends QPDecoderStream {

    
Create a Q-decoder that decodes the specified input stream.

Params:
  • in –        the input stream
/**
     * Create a Q-decoder that decodes the specified input stream.
     * @param in        the input stream
     */
    public QDecoderStream(InputStream in) {
        super(in);
    }

    
Read the next decoded byte from this input stream. The byte
is returned as an int in the range 0
to 255. If no byte is available because the end of
the stream has been reached, the value -1 is returned.
This method blocks until input data is available, the end of the
stream is detected, or an exception is thrown.

Throws:
Returns:    the next byte of data, or -1 if the end of the
            stream is reached.
/**
     * Read the next decoded byte from this input stream. The byte
     * is returned as an <code>int</code> in the range <code>0</code>
     * to <code>255</code>. If no byte is available because the end of
     * the stream has been reached, the value <code>-1</code> is returned.
     * This method blocks until input data is available, the end of the
     * stream is detected, or an exception is thrown.
     *
     * @return     the next byte of data, or <code>-1</code> if the end of the
     *             stream is reached.
     * @exception  IOException  if an I/O error occurs.
     */
    @Override
    public int read() throws IOException {
        int c = in.read();

        if (c == '_') // Return '_' as ' '
            return ' ';
        else if (c == '=') {
            // QP Encoded atom. Get the next two bytes ..
            ba[0] = (byte)in.read();
            ba[1] = (byte)in.read();
            // .. and decode them
            try {
                return ASCIIUtility.parseInt(ba, 0, 2, 16);
            } catch (NumberFormatException nex) {
                throw new IOException("Error in QP stream " + nex.getMessage());
            }
        } else
            return c;
    }
}