    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 singly occurring
    026     * &lt;LF&gt; (linefeed) characters with &lt;CR&gt;&lt;LF&gt; (carriage return
    027     * followed by linefeed), which is the NETASCII standard for representing
    028     * a newline.
    029     * You would use this class to implement ASCII file transfers requiring
    030     * conversion to NETASCII.
    031     * <p>
    032     * <p>
    033     * @author Daniel F. Savarese
    034     ***/
    035
    036    public final class ToNetASCIIOutputStream extends FilterOutputStream
    037    {
    038        private boolean __lastWasCR;
    039
    040        /***
    041         * Creates a ToNetASCIIOutputStream instance that wraps an existing
    042         * OutputStream.
    043         * <p>
    044         * @param output  The OutputStream to wrap.
    045         ***/
    046        public ToNetASCIIOutputStream(OutputStream output)
    047        {
    048            super(output);
    049            __lastWasCR = false;
    050        }
    051
    052
    053        /***
    054         * Writes a byte to the stream.    Note that a call to this method
    055         * may result in multiple writes to the underlying input stream in order
    056         * to convert naked newlines to NETASCII line separators.
    057         * This is transparent to the programmer and is only mentioned for
    058         * completeness.
    059         * <p>
    060         * @param ch The byte to write.
    061         * @exception IOException If an error occurs while writing to the underlying
    062         *            stream.
    063         ***/
    064        @Override
    065        public synchronized void write(int ch)
    066        throws IOException
    067        {
    068            switch (ch)
    069            {
    070            case '\r':
    071                __lastWasCR = true;
    072                out.write('\r');
    073                return ;
    074            case '\n':
    075                if (!__lastWasCR)
    076                    out.write('\r');
    077                //$FALL-THROUGH$
    078            default:
    079                __lastWasCR = false;
    080                out.write(ch);
    081                return ;
    082            }
    083        }
    084
    085
    086        /***
    087         * Writes a byte array to the stream.
    088         * <p>
    089         * @param buffer  The byte array to write.
    090         * @exception IOException If an error occurs while writing to the underlying
    091         *            stream.
    092         ***/
    093        @Override
    094        public synchronized void write(byte buffer[])
    095        throws IOException
    096        {
    097            write(buffer, 0, buffer.length);
    098        }
    099
    100
    101        /***
    102         * Writes a number of bytes from a byte array to the stream starting from
    103         * a given offset.
    104         * <p>
    105         * @param buffer  The byte array to write.
    106         * @param offset  The offset into the array at which to start copying data.
    107         * @param length  The number of bytes to write.
    108         * @exception IOException If an error occurs while writing to the underlying
    109         *            stream.
    110         ***/
    111        @Override
    112        public synchronized void write(byte buffer[], int offset, int length)
    113        throws IOException
    114        {
    115            while (length-- > 0)
    116                write(buffer[offset++]);
    117        }
    118
    119    }