    001    /*
    002     * Licensed to the Apache Software Foundation (ASF) under one or more
    003     * contributor license agreements.  See the NOTICE file distributed with
    004     * this work for additional information regarding copyright ownership.
    005     * The ASF licenses this file to You under the Apache License, Version 2.0
    006     * (the "License"); you may not use this file except in compliance with
    007     * the License.  You may obtain a copy of the License at
    008     *
    009     *      http://www.apache.org/licenses/LICENSE-2.0
    010     *
    011     * Unless required by applicable law or agreed to in writing, software
    012     * distributed under the License is distributed on an "AS IS" BASIS,
    013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014     * See the License for the specific language governing permissions and
    015     * limitations under the License.
    016     */
    017
    018    package org.apache.commons.net.io;
    019
    020    import java.io.FilterOutputStream;
    021    import java.io.IOException;
    022    import java.io.OutputStream;
    023
    024    /***
    025     * This class wraps an output stream, replacing all occurrences
    026     * of &lt;CR&gt;&lt;LF&gt; (carriage return followed by a linefeed),
    027     * which is the NETASCII standard for representing a newline, with the
    028     * local line separator representation.  You would use this class to
    029     * implement ASCII file transfers requiring conversion from NETASCII.
    030     * <p>
    031     * Because of the translation process, a call to <code>flush()</code> will
    032     * not flush the last byte written if that byte was a carriage
    033     * return.  A call to {@link #close  close() }, however, will
    034     * flush the carriage return.
    035     * <p>
    036     * <p>
    037     ***/
    038
    039    public final class FromNetASCIIOutputStream extends FilterOutputStream
    040    {
    041        private boolean __lastWasCR;
    042
    043        /***
    044         * Creates a FromNetASCIIOutputStream instance that wraps an existing
    045         * OutputStream.
    046         * <p>
    047         * @param output  The OutputStream to wrap.
    048         ***/
    049        public FromNetASCIIOutputStream(OutputStream output)
    050        {
    051            super(output);
    052            __lastWasCR = false;
    053        }
    054
    055
    056        private void __write(int ch) throws IOException
    057        {
    058            switch (ch)
    059            {
    060            case '\r':
    061                __lastWasCR = true;
    062                // Don't write anything.  We need to see if next one is linefeed
    063                break;
    064            case '\n':
    065                if (__lastWasCR)
    066                {
    067                    out.write(FromNetASCIIInputStream._lineSeparatorBytes);
    068                    __lastWasCR = false;
    069                    break;
    070                }
    071                __lastWasCR = false;
    072                out.write('\n');
    073                break;
    074            default:
    075                if (__lastWasCR)
    076                {
    077                    out.write('\r');
    078                    __lastWasCR = false;
    079                }
    080                out.write(ch);
    081                break;
    082            }
    083        }
    084
    085
    086        /***
    087         * Writes a byte to the stream.    Note that a call to this method
    088         * might not actually write a byte to the underlying stream until a
    089         * subsequent character is written, from which it can be determined if
    090         * a NETASCII line separator was encountered.
    091         * This is transparent to the programmer and is only mentioned for
    092         * completeness.
    093         * <p>
    094         * @param ch The byte to write.
    095         * @exception IOException If an error occurs while writing to the underlying
    096         *            stream.
    097         ***/
    098        @Override
    099        public synchronized void write(int ch)
    100        throws IOException
    101        {
    102            if (FromNetASCIIInputStream._noConversionRequired)
    103            {
    104                out.write(ch);
    105                return ;
    106            }
    107
    108            __write(ch);
    109        }
    110
    111
    112        /***
    113         * Writes a byte array to the stream.
    114         * <p>
    115         * @param buffer  The byte array to write.
    116         * @exception IOException If an error occurs while writing to the underlying
    117         *            stream.
    118         ***/
    119        @Override
    120        public synchronized void write(byte buffer[])
    121        throws IOException
    122        {
    123            write(buffer, 0, buffer.length);
    124        }
    125
    126
    127        /***
    128         * Writes a number of bytes from a byte array to the stream starting from
    129         * a given offset.
    130         * <p>
    131         * @param buffer  The byte array to write.
    132         * @param offset  The offset into the array at which to start copying data.
    133         * @param length  The number of bytes to write.
    134         * @exception IOException If an error occurs while writing to the underlying
    135         *            stream.
    136         ***/
    137        @Override
    138        public synchronized void write(byte buffer[], int offset, int length)
    139        throws IOException
    140        {
    141            if (FromNetASCIIInputStream._noConversionRequired)
    142            {
    143                // FilterOutputStream method is very slow.
    144                //super.write(buffer, offset, length);
    145                out.write(buffer, offset, length);
    146                return ;
    147            }
    148
    149            while (length-- > 0)
    150                __write(buffer[offset++]);
    151        }
    152
    153
    154        /***
    155         * Closes the stream, writing all pending data.
    156         * <p>
    157         * @exception IOException  If an error occurs while closing the stream.
    158         ***/
    159        @Override
    160        public synchronized void close()
    161        throws IOException
    162        {
    163            if (FromNetASCIIInputStream._noConversionRequired)
    164            {
    165                super.close();
    166                return ;
    167            }
    168
    169            if (__lastWasCR)
    170                out.write('\r');
    171            super.close();
    172        }
    173    }