commons-net.jar is the bytecode of Apache Commons Net library, which implements the client side of many basic Internet protocols.

Apache Commons Net Source Code files are provided in the binary packge (commons-net-3.8.0-bin.zip). You can download it at Apache Commons Net Website.

The source code of commons-net-3.8.0.jar is provided below:

⏎ org/apache/commons/net/io/DotTerminatedMessageWriter.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.commons.net.io;

import java.io.IOException;
import java.io.Writer;

/**
 * DotTerminatedMessageWriter is a class used to write messages to a
 * server that are terminated by a single dot followed by a
 * <CR><LF>
 * sequence and with double dots appearing at the begining of lines which
 * do not signal end of message yet start with a dot.  Various Internet
 * protocols such as NNTP and POP3 produce messages of this type.
 * <p>
 * This class handles the doubling of line-starting periods,
 * converts single linefeeds to NETASCII newlines, and on closing
 * will send the final message terminator dot and NETASCII newline
 * sequence.
 *
 *
 */

public final class DotTerminatedMessageWriter extends Writer
{
    private static final int NOTHING_SPECIAL_STATE = 0;
    private static final int LAST_WAS_CR_STATE = 1;
    private static final int LAST_WAS_NL_STATE = 2;

    private int state;
    private Writer output;


    /**
     * Creates a DotTerminatedMessageWriter that wraps an existing Writer
     * output destination.
     *
     * @param output  The Writer output destination to write the message.
     */
    public DotTerminatedMessageWriter(final Writer output)
    {
        super(output);
        this.output = output;
        this.state = NOTHING_SPECIAL_STATE;
    }


    /**
     * Writes a character to the output.  Note that a call to this method
     * may result in multiple writes to the underling Writer in order to
     * convert naked linefeeds to NETASCII line separators and to double
     * line-leading periods.  This is transparent to the programmer and
     * is only mentioned for completeness.
     *
     * @param ch  The character to write.
     * @throws IOException  If an error occurs while writing to the
     *            underlying output.
     */
    @Override
    public void write(final int ch) throws IOException
    {
        synchronized (lock)
        {
            switch (ch)
            {
            case '\r':
                state = LAST_WAS_CR_STATE;
                output.write('\r');
                return ;
            case '\n':
                if (state != LAST_WAS_CR_STATE) {
                    output.write('\r');
                }
                output.write('\n');
                state = LAST_WAS_NL_STATE;
                return ;
            case '.':
                // Double the dot at the beginning of a line
                if (state == LAST_WAS_NL_STATE) {
                    output.write('.');
                }
                //$FALL-THROUGH$
            default:
                state = NOTHING_SPECIAL_STATE;
                output.write(ch);
            }
        }
    }


    /**
     * Writes a number of characters from a character array to the output
     * starting from a given offset.
     *
     * @param buffer  The character array to write.
     * @param offset  The offset into the array at which to start copying data.
     * @param length  The number of characters to write.
     * @throws IOException If an error occurs while writing to the underlying
     *            output.
     */
    @Override
    public void write(final char[] buffer, int offset, int length) throws IOException
    {
        synchronized (lock)
        {
            while (length-- > 0) {
                write(buffer[offset++]);
            }
        }
    }


    /**
     * Writes a character array to the output.
     *
     * @param buffer  The character array to write.
     * @throws IOException If an error occurs while writing to the underlying
     *            output.
     */
    @Override
    public void write(final char[] buffer) throws IOException
    {
        write(buffer, 0, buffer.length);
    }


    /**
     * Writes a String to the output.
     *
     * @param string  The String to write.
     * @throws IOException If an error occurs while writing to the underlying
     *            output.
     */
    @Override
    public void write(final String string) throws IOException
    {
        write(string.toCharArray());
    }


    /**
     * Writes part of a String to the output starting from a given offset.
     *
     * @param string  The String to write.
     * @param offset  The offset into the String at which to start copying data.
     * @param length  The number of characters to write.
     * @throws IOException If an error occurs while writing to the underlying
     *            output.
     */
    @Override
    public void write(final String string, final int offset, final int length) throws IOException
    {
        write(string.toCharArray(), offset, length);
    }


    /**
     * Flushes the underlying output, writing all buffered output.
     *
     * @throws IOException If an error occurs while writing to the underlying
     *            output.
     */
    @Override
    public void flush() throws IOException
    {
        synchronized (lock)
        {
            output.flush();
        }
    }


    /**
     * Flushes the underlying output, writing all buffered output, but doesn't
     * actually close the underlying stream.  The underlying stream may still
     * be used for communicating with the server and therefore is not closed.
     *
     * @throws IOException If an error occurs while writing to the underlying
     *            output or closing the Writer.
     */
    @Override
    public void close() throws IOException
    {
        synchronized (lock)
        {
            if (output == null) {
                return ;
            }

            if (state == LAST_WAS_CR_STATE) {
                output.write('\n');
            } else if (state != LAST_WAS_NL_STATE) {
                output.write("\r\n");
            }

            output.write(".\r\n");

            output.flush();
            output = null;
        }
    }

}

⏎ org/apache/commons/net/io/DotTerminatedMessageWriter.java

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File name: commons-net-3.8.0-sources.jar
File size: 437325 bytes
Release date: 2020-01-22
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