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