    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     * @author Daniel F. Savarese
    038     ***/
    039
    040    public final class FromNetASCIIOutputStream extends FilterOutputStream
    041    {
    042        private boolean __lastWasCR;
    043
    044        /***
    045         * Creates a FromNetASCIIOutputStream instance that wraps an existing
    046         * OutputStream.
    047         * <p>
    048         * @param output  The OutputStream to wrap.
    049         ***/
    050        public FromNetASCIIOutputStream(OutputStream output)
    051        {
    052            super(output);
    053            __lastWasCR = false;
    054        }
    055
    056
    057        private void __write(int ch) throws IOException
    058        {
    059            switch (ch)
    060            {
    061            case '\r':
    062                __lastWasCR = true;
    063                // Don't write anything.  We need to see if next one is linefeed
    064                break;
    065            case '\n':
    066                if (__lastWasCR)
    067                {
    068                    out.write(FromNetASCIIInputStream._lineSeparatorBytes);
    069                    __lastWasCR = false;
    070                    break;
    071                }
    072                __lastWasCR = false;
    073                out.write('\n');
    074                break;
    075            default:
    076                if (__lastWasCR)
    077                {
    078                    out.write('\r');
    079                    __lastWasCR = false;
    080                }
    081                out.write(ch);
    082                break;
    083            }
    084        }
    085
    086
    087        /***
    088         * Writes a byte to the stream.    Note that a call to this method
    089         * might not actually write a byte to the underlying stream until a
    090         * subsequent character is written, from which it can be determined if
    091         * a NETASCII line separator was encountered.
    092         * This is transparent to the programmer and is only mentioned for
    093         * completeness.
    094         * <p>
    095         * @param ch The byte to write.
    096         * @exception IOException If an error occurs while writing to the underlying
    097         *            stream.
    098         ***/
    099        @Override
    100        public synchronized void write(int ch)
    101        throws IOException
    102        {
    103            if (FromNetASCIIInputStream._noConversionRequired)
    104            {
    105                out.write(ch);
    106                return ;
    107            }
    108
    109            __write(ch);
    110        }
    111
    112
    113        /***
    114         * Writes a byte array to the stream.
    115         * <p>
    116         * @param buffer  The byte array to write.
    117         * @exception IOException If an error occurs while writing to the underlying
    118         *            stream.
    119         ***/
    120        @Override
    121        public synchronized void write(byte buffer[])
    122        throws IOException
    123        {
    124            write(buffer, 0, buffer.length);
    125        }
    126
    127
    128        /***
    129         * Writes a number of bytes from a byte array to the stream starting from
    130         * a given offset.
    131         * <p>
    132         * @param buffer  The byte array to write.
    133         * @param offset  The offset into the array at which to start copying data.
    134         * @param length  The number of bytes to write.
    135         * @exception IOException If an error occurs while writing to the underlying
    136         *            stream.
    137         ***/
    138        @Override
    139        public synchronized void write(byte buffer[], int offset, int length)
    140        throws IOException
    141        {
    142            if (FromNetASCIIInputStream._noConversionRequired)
    143            {
    144                // FilterOutputStream method is very slow.
    145                //super.write(buffer, offset, length);
    146                out.write(buffer, offset, length);
    147                return ;
    148            }
    149
    150            while (length-- > 0)
    151                __write(buffer[offset++]);
    152        }
    153
    154
    155        /***
    156         * Closes the stream, writing all pending data.
    157         * <p>
    158         * @exception IOException  If an error occurs while closing the stream.
    159         ***/
    160        @Override
    161        public synchronized void close()
    162        throws IOException
    163        {
    164            if (FromNetASCIIInputStream._noConversionRequired)
    165            {
    166                super.close();
    167                return ;
    168            }
    169
    170            if (__lastWasCR)
    171                out.write('\r');
    172            super.close();
    173        }
    174    }