commons-net.jar Source Code

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:

✍: FYIcenter

org/apache/commons/net/nntp/NNTPClient.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.nntp;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.Reader;
import java.io.StringWriter;
import java.io.Writer;
import java.util.ArrayList;
import java.util.Vector;

import org.apache.commons.net.MalformedServerReplyException;
import org.apache.commons.net.io.DotTerminatedMessageReader;
import org.apache.commons.net.io.DotTerminatedMessageWriter;
import org.apache.commons.net.io.Util;
import org.apache.commons.net.util.NetConstants;

/**
 * NNTPClient encapsulates all the functionality necessary to post and
 * retrieve articles from an NNTP server.  As with all classes derived
 * from {@link org.apache.commons.net.SocketClient},
 * you must first connect to the server with
 * {@link org.apache.commons.net.SocketClient#connect  connect }
 * before doing anything, and finally
 * {@link org.apache.commons.net.nntp.NNTP#disconnect  disconnect() }
 * after you're completely finished interacting with the server.
 * Remember that the
 * {@link org.apache.commons.net.nntp.NNTP#isAllowedToPost isAllowedToPost()}
 *  method is defined in
 * {@link org.apache.commons.net.nntp.NNTP}.
 * <p>
 * You should keep in mind that the NNTP server may choose to prematurely
 * close a connection if the client has been idle for longer than a
 * given time period or if the server is being shutdown by the operator or
 * some other reason.  The NNTP class will detect a
 * premature NNTP server connection closing when it receives a
 * {@link org.apache.commons.net.nntp.NNTPReply#SERVICE_DISCONTINUED NNTPReply.SERVICE_DISCONTINUED }
 *  response to a command.
 * When that occurs, the NNTP class method encountering that reply will throw
 * an {@link org.apache.commons.net.nntp.NNTPConnectionClosedException}
 * .
 * <code>NNTPConectionClosedException</code>
 * is a subclass of <code> IOException </code> and therefore need not be
 * caught separately, but if you are going to catch it separately, its
 * catch block must appear before the more general <code> IOException </code>
 * catch block.  When you encounter an
 * {@link org.apache.commons.net.nntp.NNTPConnectionClosedException}
 * , you must disconnect the connection with
 * {@link org.apache.commons.net.nntp.NNTP#disconnect  disconnect() }
 *  to properly clean up the
 * system resources used by NNTP.  Before disconnecting, you may check the
 * last reply code and text with
 * {@link org.apache.commons.net.nntp.NNTP#getReplyCode  getReplyCode } and
 * {@link org.apache.commons.net.nntp.NNTP#getReplyString  getReplyString }.
 * <p>
 * Rather than list it separately for each method, we mention here that
 * every method communicating with the server and throwing an IOException
 * can also throw a
 * {@link org.apache.commons.net.MalformedServerReplyException}
 * , which is a subclass
 * of IOException.  A MalformedServerReplyException will be thrown when
 * the reply received from the server deviates enough from the protocol
 * specification that it cannot be interpreted in a useful manner despite
 * attempts to be as lenient as possible.
 *
 * @see NNTP
 * @see NNTPConnectionClosedException
 * @see org.apache.commons.net.MalformedServerReplyException
 */

public class NNTPClient extends NNTP
{

    private static final NewsgroupInfo[] EMPTY_NEWSGROUP_INFO_ARRAY = new NewsgroupInfo[0];

    /**
     * Parse the reply and store the id and number in the pointer.
     *
     * @param reply the reply to parse "22n nnn <aaa>"
     * @param pointer the pointer to update
     *
     * @throws MalformedServerReplyException if response could not be parsed
     */
    private void parseArticlePointer(final String reply, final ArticleInfo pointer)
    throws MalformedServerReplyException
    {
        final String tokens[] = reply.split(" ");
        if (tokens.length >= 3) { // OK, we can parset the line
            int i = 1; // skip reply code
            try
            {
                // Get article number
                pointer.articleNumber = Long.parseLong(tokens[i++]);
                // Get article id
                pointer.articleId = tokens[i++];
                return; // done
            }
            catch (final NumberFormatException e)
            {
                // drop through and raise exception
            }
        }
        throw new MalformedServerReplyException(
            "Could not parse article pointer.\nServer reply: " + reply);
    }

    /*
     * 211 n f l s group selected
     *     (n = estimated number of articles in group,
     *     f = first article number in the group,
     *     l = last article number in the group,
     *     s = name of the group.)
     */

    private static void parseGroupReply(final String reply, final NewsgroupInfo info)
    throws MalformedServerReplyException
    {
        final String tokens[] = reply.split(" ");
        if (tokens.length >= 5) {
            int i = 1;  // Skip numeric response value
            try
            {
                // Get estimated article count
                info.setArticleCount(Long.parseLong(tokens[i++]));
                // Get first article number
                info.setFirstArticle(Long.parseLong(tokens[i++]));
                // Get last article number
                info.setLastArticle(Long.parseLong(tokens[i++]));
                // Get newsgroup name
                info.setNewsgroup(tokens[i++]);

                info.setPostingPermission(NewsgroupInfo.UNKNOWN_POSTING_PERMISSION);
                return ;
            } catch (final NumberFormatException e)
            {
               // drop through to report error
            }
        }

        throw new MalformedServerReplyException(
            "Could not parse newsgroup info.\nServer reply: " + reply);
    }


    // Format: group last first p
    static NewsgroupInfo parseNewsgroupListEntry(final String entry)
    {
        final String tokens[] = entry.split(" ");
        if (tokens.length < 4) {
            return null;
        }
        final NewsgroupInfo result = new NewsgroupInfo();

        int i = 0;

        result.setNewsgroup(tokens[i++]);

        try
        {
            final long lastNum = Long.parseLong(tokens[i++]);
            final long firstNum = Long.parseLong(tokens[i++]);
            result.setFirstArticle(firstNum);
            result.setLastArticle(lastNum);
            if ((firstNum == 0) && (lastNum == 0)) {
                result.setArticleCount(0);
            } else {
                result.setArticleCount(lastNum - firstNum + 1);
            }
        } catch (final NumberFormatException e) {
            return null;
        }

        switch (tokens[i++].charAt(0))
        {
        case 'y':
        case 'Y':
            result.setPostingPermission(
                NewsgroupInfo.PERMITTED_POSTING_PERMISSION);
            break;
        case 'n':
        case 'N':
            result.setPostingPermission(
                NewsgroupInfo.PROHIBITED_POSTING_PERMISSION);
            break;
        case 'm':
        case 'M':
            result.setPostingPermission(
                NewsgroupInfo.MODERATED_POSTING_PERMISSION);
            break;
        default:
            result.setPostingPermission(
                NewsgroupInfo.UNKNOWN_POSTING_PERMISSION);
            break;
        }

        return result;
    }

    /**
     * Parse a response line from {@link #retrieveArticleInfo(long, long)}.
     *
     * @param line a response line
     * @return the parsed {@link Article}, if unparseable then isDummy()
     * will be true, and the subject will contain the raw info.
     * @since 3.0
     */
    static Article parseArticleEntry(final String line) {
        // Extract the article information
        // Mandatory format (from NNTP RFC 2980) is :
        // articleNumber\tSubject\tAuthor\tDate\tID\tReference(s)\tByte Count\tLine Count

        final Article article = new Article();
        article.setSubject(line); // in case parsing fails
        final String parts[] = line.split("\t");
        if (parts.length > 6) {
            int i = 0;
            try {
                article.setArticleNumber(Long.parseLong(parts[i++]));
                article.setSubject(parts[i++]);
                article.setFrom(parts[i++]);
                article.setDate(parts[i++]);
                article.setArticleId(parts[i++]);
                article.addReference(parts[i++]);
            } catch (final NumberFormatException e) {
                // ignored, already handled
            }
        }
        return article;
    }

    private NewsgroupInfo[] readNewsgroupListing() throws IOException
    {

        // Start of with a big vector because we may be reading a very large
        // amount of groups.
        final Vector<NewsgroupInfo> list = new Vector<>(2048);

        String line;
        try (final BufferedReader reader = new DotTerminatedMessageReader(_reader_)) {
            while ((line = reader.readLine()) != null) {
                final NewsgroupInfo tmp = parseNewsgroupListEntry(line);
                if (tmp != null) {
                    list.addElement(tmp);
                } else {
                    throw new MalformedServerReplyException(line);
                }
            }
        }
        final int size;
        if ((size = list.size()) < 1) {
            return EMPTY_NEWSGROUP_INFO_ARRAY;
        }

        final NewsgroupInfo[] info = new NewsgroupInfo[size];
        list.copyInto(info);

        return info;
    }


    private BufferedReader retrieve(final int command, final String articleId, final ArticleInfo pointer)
    throws IOException
    {
        if (articleId != null)
        {
            if (!NNTPReply.isPositiveCompletion(sendCommand(command, articleId))) {
                return null;
            }
        }
        else
        {
            if (!NNTPReply.isPositiveCompletion(sendCommand(command))) {
                return null;
            }
        }


        if (pointer != null) {
            parseArticlePointer(getReplyString(), pointer);
        }

        return new DotTerminatedMessageReader(_reader_);
    }


    private BufferedReader retrieve(final int command, final long articleNumber, final ArticleInfo pointer)
    throws IOException
    {
        if (!NNTPReply.isPositiveCompletion(sendCommand(command,
                                            Long.toString(articleNumber)))) {
            return null;
        }

        if (pointer != null) {
            parseArticlePointer(getReplyString(), pointer);
        }

        return new DotTerminatedMessageReader(_reader_);
    }



    /**
     * Retrieves an article from the NNTP server.  The article is referenced
     * by its unique article identifier (including the enclosing &lt; and &gt;).
     * The article number and identifier contained in the server reply
     * are returned through an ArticleInfo.  The <code> articleId </code>
     * field of the ArticleInfo cannot always be trusted because some
     * NNTP servers do not correctly follow the RFC 977 reply format.
     * <p>
     * A DotTerminatedMessageReader is returned from which the article can
     * be read.  If the article does not exist, null is returned.
     * <p>
     * You must not issue any commands to the NNTP server (i.e., call any
     * other methods) until you finish reading the message from the returned
     * BufferedReader instance.
     * The NNTP protocol uses the same stream for issuing commands as it does
     * for returning results.  Therefore the returned BufferedReader actually reads
     * directly from the NNTP connection.  After the end of message has been
     * reached, new commands can be executed and their replies read.  If
     * you do not follow these requirements, your program will not work
     * properly.
     * <p>
     * @param articleId  The unique article identifier of the article to
     *     retrieve.  If this parameter is null, the currently selected
     *     article is retrieved.
     * @param pointer    A parameter through which to return the article's
     *   number and unique id.  The articleId field cannot always be trusted
     *   because of server deviations from RFC 977 reply formats.  You may
     *   set this parameter to null if you do not desire to retrieve the
     *   returned article information.
     * @return A DotTerminatedMessageReader instance from which the article
     *         can be read.  null if the article does not exist.
     * @throws NNTPConnectionClosedException
     *      If the NNTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send NNTP reply code 400.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public BufferedReader retrieveArticle(final String articleId, final ArticleInfo pointer)
    throws IOException
    {
        return retrieve(NNTPCommand.ARTICLE, articleId, pointer);

    }

    /**
     * Same as <code> retrieveArticle(articleId, (ArticleInfo) null) </code>
     * Note: the return can be cast to a {@link BufferedReader}
     * @param articleId the article id to retrieve
     * @return A DotTerminatedMessageReader instance from which the article can be read.
     * null if the article does not exist.
     * @throws IOException if an IO error occurs
     */
    public Reader retrieveArticle(final String articleId) throws IOException
    {
        return retrieveArticle(articleId, (ArticleInfo) null);
    }

    /**
     * Same as <code> retrieveArticle((String) null) </code>
     * Note: the return can be cast to a {@link BufferedReader}
     * @return A DotTerminatedMessageReader instance from which the article can be read.
     * null if the article does not exist.
     * @throws IOException if an IO error occurs
     */
    public Reader retrieveArticle() throws IOException
    {
        return retrieveArticle((String) null);
    }


    /**
     * Retrieves an article from the currently selected newsgroup.  The
     * article is referenced by its article number.
     * The article number and identifier contained in the server reply
     * are returned through an ArticleInfo.  The <code> articleId </code>
     * field of the ArticleInfo cannot always be trusted because some
     * NNTP servers do not correctly follow the RFC 977 reply format.
     * <p>
     * A DotTerminatedMessageReader is returned from which the article can
     * be read.  If the article does not exist, null is returned.
     * <p>
     * You must not issue any commands to the NNTP server (i.e., call any
     * other methods) until you finish reading the message from the returned
     * BufferedReader instance.
     * The NNTP protocol uses the same stream for issuing commands as it does
     * for returning results.  Therefore the returned BufferedReader actually reads
     * directly from the NNTP connection.  After the end of message has been
     * reached, new commands can be executed and their replies read.  If
     * you do not follow these requirements, your program will not work
     * properly.
     * <p>
     * @param articleNumber  The number of the the article to
     *     retrieve.
     * @param pointer    A parameter through which to return the article's
     *   number and unique id.  The articleId field cannot always be trusted
     *   because of server deviations from RFC 977 reply formats.  You may
     *   set this parameter to null if you do not desire to retrieve the
     *   returned article information.
     * @return A DotTerminatedMessageReader instance from which the article
     *         can be read.  null if the article does not exist.
     * @throws NNTPConnectionClosedException
     *      If the NNTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send NNTP reply code 400.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public BufferedReader retrieveArticle(final long articleNumber, final ArticleInfo pointer)
    throws IOException
    {
        return retrieve(NNTPCommand.ARTICLE, articleNumber, pointer);
    }

    /**
     * Same as <code> retrieveArticle(articleNumber, null) </code>
     * @param articleNumber the article number to fetch
     * @return A DotTerminatedMessageReader instance from which the article
     *         can be read.  null if the article does not exist.
     * @throws IOException if an IO error occurs
     */
    public BufferedReader retrieveArticle(final long articleNumber) throws IOException
    {
        return retrieveArticle(articleNumber, null);
    }



    /**
     * Retrieves an article header from the NNTP server.  The article is
     * referenced
     * by its unique article identifier (including the enclosing &lt; and &gt;).
     * The article number and identifier contained in the server reply
     * are returned through an ArticleInfo.  The <code> articleId </code>
     * field of the ArticleInfo cannot always be trusted because some
     * NNTP servers do not correctly follow the RFC 977 reply format.
     * <p>
     * A DotTerminatedMessageReader is returned from which the article can
     * be read.  If the article does not exist, null is returned.
     * <p>
     * You must not issue any commands to the NNTP server (i.e., call any
     * other methods) until you finish reading the message from the returned
     * BufferedReader instance.
     * The NNTP protocol uses the same stream for issuing commands as it does
     * for returning results.  Therefore the returned BufferedReader actually reads
     * directly from the NNTP connection.  After the end of message has been
     * reached, new commands can be executed and their replies read.  If
     * you do not follow these requirements, your program will not work
     * properly.
     * <p>
     * @param articleId  The unique article identifier of the article whose
     *    header is being retrieved.  If this parameter is null, the
     *    header of the currently selected article is retrieved.
     * @param pointer    A parameter through which to return the article's
     *   number and unique id.  The articleId field cannot always be trusted
     *   because of server deviations from RFC 977 reply formats.  You may
     *   set this parameter to null if you do not desire to retrieve the
     *   returned article information.
     * @return A DotTerminatedMessageReader instance from which the article
     *         header can be read.  null if the article does not exist.
     * @throws NNTPConnectionClosedException
     *      If the NNTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send NNTP reply code 400.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public BufferedReader retrieveArticleHeader(final String articleId, final ArticleInfo pointer)
    throws IOException
    {
        return retrieve(NNTPCommand.HEAD, articleId, pointer);

    }

    /**
     * Same as <code> retrieveArticleHeader(articleId, (ArticleInfo) null) </code>
     *  Note: the return can be cast to a {@link BufferedReader}
     * @param articleId the article id  to fetch
     * @return the reader
     * @throws IOException if an error occurs
     */
    public Reader retrieveArticleHeader(final String articleId) throws IOException
    {
        return retrieveArticleHeader(articleId, (ArticleInfo) null);
    }

    /**
     * Same as <code> retrieveArticleHeader((String) null) </code>
     *  Note: the return can be cast to a {@link BufferedReader}
     * @return the reader
     * @throws IOException if an error occurs
     */
    public Reader retrieveArticleHeader() throws IOException
    {
        return retrieveArticleHeader((String) null);
    }


    /**
     * Retrieves an article header from the currently selected newsgroup.  The
     * article is referenced by its article number.
     * The article number and identifier contained in the server reply
     * are returned through an ArticleInfo.  The <code> articleId </code>
     * field of the ArticleInfo cannot always be trusted because some
     * NNTP servers do not correctly follow the RFC 977 reply format.
     * <p>
     * A DotTerminatedMessageReader is returned from which the article can
     * be read.  If the article does not exist, null is returned.
     * <p>
     * You must not issue any commands to the NNTP server (i.e., call any
     * other methods) until you finish reading the message from the returned
     * BufferedReader instance.
     * The NNTP protocol uses the same stream for issuing commands as it does
     * for returning results.  Therefore the returned BufferedReader actually reads
     * directly from the NNTP connection.  After the end of message has been
     * reached, new commands can be executed and their replies read.  If
     * you do not follow these requirements, your program will not work
     * properly.
     * <p>
     * @param articleNumber  The number of the the article whose header is
     *     being retrieved.
     * @param pointer    A parameter through which to return the article's
     *   number and unique id.  The articleId field cannot always be trusted
     *   because of server deviations from RFC 977 reply formats.  You may
     *   set this parameter to null if you do not desire to retrieve the
     *   returned article information.
     * @return A DotTerminatedMessageReader instance from which the article
     *         header can be read.  null if the article does not exist.
     * @throws NNTPConnectionClosedException
     *      If the NNTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send NNTP reply code 400.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public BufferedReader retrieveArticleHeader(final long articleNumber,
                                        final ArticleInfo pointer)
    throws IOException
    {
        return retrieve(NNTPCommand.HEAD, articleNumber, pointer);
    }


    /**
     * Same as <code> retrieveArticleHeader(articleNumber, null) </code>
     *
     * @param articleNumber the article number
     * @return the reader
     * @throws IOException if an error occurs
     */
    public BufferedReader retrieveArticleHeader(final long articleNumber) throws IOException
    {
        return retrieveArticleHeader(articleNumber, null);
    }



    /**
     * Retrieves an article body from the NNTP server.  The article is
     * referenced
     * by its unique article identifier (including the enclosing &lt; and &gt;).
     * The article number and identifier contained in the server reply
     * are returned through an ArticleInfo.  The <code> articleId </code>
     * field of the ArticleInfo cannot always be trusted because some
     * NNTP servers do not correctly follow the RFC 977 reply format.
     * <p>
     * A DotTerminatedMessageReader is returned from which the article can
     * be read.  If the article does not exist, null is returned.
     * <p>
     * You must not issue any commands to the NNTP server (i.e., call any
     * other methods) until you finish reading the message from the returned
     * BufferedReader instance.
     * The NNTP protocol uses the same stream for issuing commands as it does
     * for returning results.  Therefore the returned BufferedReader actually reads
     * directly from the NNTP connection.  After the end of message has been
     * reached, new commands can be executed and their replies read.  If
     * you do not follow these requirements, your program will not work
     * properly.
     * <p>
     * @param articleId  The unique article identifier of the article whose
     *    body is being retrieved.  If this parameter is null, the
     *    body of the currently selected article is retrieved.
     * @param pointer    A parameter through which to return the article's
     *   number and unique id.  The articleId field cannot always be trusted
     *   because of server deviations from RFC 977 reply formats.  You may
     *   set this parameter to null if you do not desire to retrieve the
     *   returned article information.
     * @return A DotTerminatedMessageReader instance from which the article
     *         body can be read.  null if the article does not exist.
     * @throws NNTPConnectionClosedException
     *      If the NNTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send NNTP reply code 400.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public BufferedReader retrieveArticleBody(final String articleId, final ArticleInfo pointer)
    throws IOException
    {
        return retrieve(NNTPCommand.BODY, articleId, pointer);

    }

    /**
     * Same as <code> retrieveArticleBody(articleId, (ArticleInfo) null) </code>
     *  Note: the return can be cast to a {@link BufferedReader}
     * @param articleId the article id
     * @return A DotTerminatedMessageReader instance from which the article
     *         body can be read.  null if the article does not exist.
     * @throws IOException if an error occurs
     */
    public Reader retrieveArticleBody(final String articleId) throws IOException
    {
        return retrieveArticleBody(articleId, (ArticleInfo) null);
    }

    /**
     * Same as <code> retrieveArticleBody(null) </code>
     *  Note: the return can be cast to a {@link BufferedReader}
     * @return A DotTerminatedMessageReader instance from which the article
     *         body can be read.  null if the article does not exist.
     * @throws IOException if an error occurs
     */
    public Reader retrieveArticleBody() throws IOException
    {
        return retrieveArticleBody(null);
    }


    /**
     * Retrieves an article body from the currently selected newsgroup.  The
     * article is referenced by its article number.
     * The article number and identifier contained in the server reply
     * are returned through an ArticleInfo.  The <code> articleId </code>
     * field of the ArticleInfo cannot always be trusted because some
     * NNTP servers do not correctly follow the RFC 977 reply format.
     * <p>
     * A DotTerminatedMessageReader is returned from which the article can
     * be read.  If the article does not exist, null is returned.
     * <p>
     * You must not issue any commands to the NNTP server (i.e., call any
     * other methods) until you finish reading the message from the returned
     * BufferedReader instance.
     * The NNTP protocol uses the same stream for issuing commands as it does
     * for returning results.  Therefore the returned BufferedReader actually reads
     * directly from the NNTP connection.  After the end of message has been
     * reached, new commands can be executed and their replies read.  If
     * you do not follow these requirements, your program will not work
     * properly.
     * <p>
     * @param articleNumber  The number of the the article whose body is
     *     being retrieved.
     * @param pointer    A parameter through which to return the article's
     *   number and unique id.  The articleId field cannot always be trusted
     *   because of server deviations from RFC 977 reply formats.  You may
     *   set this parameter to null if you do not desire to retrieve the
     *   returned article information.
     * @return A DotTerminatedMessageReader instance from which the article
     *         body can be read.  null if the article does not exist.
     * @throws NNTPConnectionClosedException
     *      If the NNTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send NNTP reply code 400.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public BufferedReader retrieveArticleBody(final long articleNumber,
                                      final ArticleInfo pointer)
    throws IOException
    {
        return retrieve(NNTPCommand.BODY, articleNumber, pointer);
    }


    /**
     * Same as <code> retrieveArticleBody(articleNumber, null) </code>
     * @param articleNumber the article number
     * @return the reader
     * @throws IOException if an error occurs
     */
    public BufferedReader retrieveArticleBody(final long articleNumber) throws IOException
    {
        return retrieveArticleBody(articleNumber, null);
    }


    /**
     * Select the specified newsgroup to be the target of for future article
     * retrieval and posting operations.  Also return the newsgroup
     * information contained in the server reply through the info parameter.
     * <p>
     * @param newsgroup  The newsgroup to select.
     * @param info  A parameter through which the newsgroup information of
     *      the selected newsgroup contained in the server reply is returned.
     *      Set this to null if you do not desire this information.
     * @return True if the newsgroup exists and was selected, false otherwise.
     * @throws NNTPConnectionClosedException
     *      If the NNTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send NNTP reply code 400.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean selectNewsgroup(final String newsgroup, final NewsgroupInfo info)
    throws IOException
    {
        if (!NNTPReply.isPositiveCompletion(group(newsgroup))) {
            return false;
        }

        if (info != null) {
            parseGroupReply(getReplyString(), info);
        }

        return true;
    }

    /**
     * Same as <code> selectNewsgroup(newsgroup, null) </code>
     * @param newsgroup the newsgroup name
     * @return true if newsgroup exist and was selected
     * @throws IOException if an error occurs
     */
    public boolean selectNewsgroup(final String newsgroup) throws IOException
    {
        return selectNewsgroup(newsgroup, null);
    }

    /**
     * List the command help from the server.
     * <p>
     * @return The sever help information.
     * @throws NNTPConnectionClosedException
     *      If the NNTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send NNTP reply code 400.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public String listHelp() throws IOException
    {
        if (!NNTPReply.isInformational(help())) {
            return null;
        }

        try (final StringWriter help = new StringWriter();
                final BufferedReader reader = new DotTerminatedMessageReader(_reader_)) {
            Util.copyReader(reader, help);
            return help.toString();
        }
    }

    /**
     * Send a "LIST OVERVIEW.FMT" command to the server.
     *
     * @return the contents of the Overview format, of {@code null} if the command failed
     * @throws IOException on error
     */
    public String[] listOverviewFmt() throws IOException
    {
        if (!NNTPReply.isPositiveCompletion(sendCommand("LIST", "OVERVIEW.FMT"))) {
            return null;
        }

        try (final BufferedReader reader = new DotTerminatedMessageReader(_reader_)) {
            String line;
            final ArrayList<String> list = new ArrayList<>();
            while ((line = reader.readLine()) != null) {
                list.add(line);
            }
            return list.toArray(NetConstants.EMPTY_STRING_ARRAY);
        }
    }

    /**
     * Select an article by its unique identifier (including enclosing
     * &lt; and &gt;) and return its article number and id through the
     * pointer parameter.  This is achieved through the STAT command.
     * According to RFC 977, this will NOT set the current article pointer
     * on the server.  To do that, you must reference the article by its
     * number.
     * <p>
     * @param articleId  The unique article identifier of the article that
     *    is being selectedd.  If this parameter is null, the
     *    body of the current article is selected
     * @param pointer    A parameter through which to return the article's
     *   number and unique id.  The articleId field cannot always be trusted
     *   because of server deviations from RFC 977 reply formats.  You may
     *   set this parameter to null if you do not desire to retrieve the
     *   returned article information.
     * @return True if successful, false if not.
     * @throws NNTPConnectionClosedException
     *      If the NNTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send NNTP reply code 400.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean selectArticle(final String articleId, final ArticleInfo pointer)
    throws IOException
    {
        if (articleId != null) {
            if (!NNTPReply.isPositiveCompletion(stat(articleId))) {
                return false;
            }
        } else {
            if (!NNTPReply.isPositiveCompletion(stat())) {
                return false;
            }
        }

        if (pointer != null) {
            parseArticlePointer(getReplyString(), pointer);
        }

        return true;
    }

    /**
     * Same as <code> selectArticle(articleId, (ArticleInfo) null) </code>
     * @param articleId the article Id
     * @return true if successful
     * @throws IOException on error
     */
    public boolean selectArticle(final String articleId) throws IOException
    {
        return selectArticle(articleId, (ArticleInfo) null);
    }

    /***
     * Same as <code> selectArticle((String) null, articleId) </code>.  Useful
     * for retrieving the current article number.
     * @param pointer to the article
     * @return true if OK
     * @throws IOException on error
     */
    public boolean selectArticle(final ArticleInfo pointer) throws IOException
    {
        return selectArticle(null, pointer);
    }


    /**
     * Select an article in the currently selected newsgroup by its number.
     * and return its article number and id through the
     * pointer parameter.  This is achieved through the STAT command.
     * According to RFC 977, this WILL set the current article pointer
     * on the server.  Use this command to select an article before retrieving
     * it, or to obtain an article's unique identifier given its number.
     * <p>
     * @param articleNumber The number of the article to select from the
     *       currently selected newsgroup.
     * @param pointer    A parameter through which to return the article's
     *   number and unique id.  Although the articleId field cannot always
     *   be trusted because of server deviations from RFC 977 reply formats,
     *   we haven't found a server that misformats this information in response
     *   to this particular command.  You may set this parameter to null if
     *   you do not desire to retrieve the returned article information.
     * @return True if successful, false if not.
     * @throws NNTPConnectionClosedException
     *      If the NNTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send NNTP reply code 400.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean selectArticle(final long articleNumber, final ArticleInfo pointer)
    throws IOException
    {
        if (!NNTPReply.isPositiveCompletion(stat(articleNumber))) {
            return false;
        }

        if (pointer != null) {
            parseArticlePointer(getReplyString(), pointer);
        }

        return true;
    }


    /** Same as <code> selectArticle(articleNumber, null) </code>
     * @param articleNumber the numger
     * @return true if successful
     * @throws IOException on error */
    public boolean selectArticle(final long articleNumber) throws IOException
    {
        return selectArticle(articleNumber, null);
    }


    /**
     * Select the article preceeding the currently selected article in the
     * currently selected newsgroup and return its number and unique id
     * through the pointer parameter.  Because of deviating server
     * implementations, the articleId information cannot be trusted.  To
     * obtain the article identifier, issue a
     * <code> selectArticle(pointer.articleNumber, pointer) </code> immediately
     * afterward.
     * <p>
     * @param pointer    A parameter through which to return the article's
     *   number and unique id.  The articleId field cannot always be trusted
     *   because of server deviations from RFC 977 reply formats.  You may
     *   set this parameter to null if you do not desire to retrieve the
     *   returned article information.
     * @return True if successful, false if not (e.g., there is no previous
     *     article).
     * @throws NNTPConnectionClosedException
     *      If the NNTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send NNTP reply code 400.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean selectPreviousArticle(final ArticleInfo pointer)
    throws IOException
    {
        if (!NNTPReply.isPositiveCompletion(last())) {
            return false;
        }

        if (pointer != null) {
            parseArticlePointer(getReplyString(), pointer);
        }

        return true;
    }

    /** Same as <code> selectPreviousArticle((ArticleInfo) null) </code>
     * @return true if successful
     * @throws IOException on error */
    public boolean selectPreviousArticle() throws IOException
    {
        return selectPreviousArticle((ArticleInfo) null);
    }


    /**
     * Select the article following the currently selected article in the
     * currently selected newsgroup and return its number and unique id
     * through the pointer parameter.  Because of deviating server
     * implementations, the articleId information cannot be trusted.  To
     * obtain the article identifier, issue a
     * <code> selectArticle(pointer.articleNumber, pointer) </code> immediately
     * afterward.
     * <p>
     * @param pointer    A parameter through which to return the article's
     *   number and unique id.  The articleId field cannot always be trusted
     *   because of server deviations from RFC 977 reply formats.  You may
     *   set this parameter to null if you do not desire to retrieve the
     *   returned article information.
     * @return True if successful, false if not (e.g., there is no following
     *         article).
     * @throws NNTPConnectionClosedException
     *      If the NNTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send NNTP reply code 400.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean selectNextArticle(final ArticleInfo pointer) throws IOException
    {
        if (!NNTPReply.isPositiveCompletion(next())) {
            return false;
        }

        if (pointer != null) {
            parseArticlePointer(getReplyString(), pointer);
        }

        return true;
    }


    /** Same as <code> selectNextArticle((ArticleInfo) null) </code>
     * @return true if successful
     * @throws IOException on error */
    public boolean selectNextArticle() throws IOException
    {
        return selectNextArticle((ArticleInfo) null);
    }


    /**
     * List all newsgroups served by the NNTP server.  If no newsgroups
     * are served, a zero length array will be returned.  If the command
     * fails, null will be returned.
     * The method uses the "LIST" command.
     * <p>
     * @return An array of NewsgroupInfo instances containing the information
     *    for each newsgroup served by the NNTP server.   If no newsgroups
     *    are served, a zero length array will be returned.  If the command
     *    fails, null will be returned.
     * @throws NNTPConnectionClosedException
     *      If the NNTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send NNTP reply code 400.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     * @see #iterateNewsgroupListing()
     * @see #iterateNewsgroups()
     */
    public NewsgroupInfo[] listNewsgroups() throws IOException
    {
        if (!NNTPReply.isPositiveCompletion(list())) {
            return null;
        }

        return readNewsgroupListing();
    }

    /**
     * List all newsgroups served by the NNTP server.  If no newsgroups
     * are served, no entries will be returned.
     * The method uses the "LIST" command.
     * <p>
     * @return An iterable of NewsgroupInfo instances containing the information
     *    for each newsgroup served by the NNTP server.   If no newsgroups
     *    are served, no entries will be returned.
     * @throws NNTPConnectionClosedException
     *      If the NNTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send NNTP reply code 400.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     * @since 3.0
     */
    public Iterable<String> iterateNewsgroupListing() throws IOException {
        if (NNTPReply.isPositiveCompletion(list())) {
            return new ReplyIterator(_reader_);
        }
        throw new IOException("LIST command failed: "+getReplyString());
    }

    /**
     * List all newsgroups served by the NNTP server.  If no newsgroups
     * are served, no entries will be returned.
     * The method uses the "LIST" command.
     * <p>
     * @return An iterable of Strings containing the raw information
     *    for each newsgroup served by the NNTP server.   If no newsgroups
     *    are served, no entries will be returned.
     * @throws NNTPConnectionClosedException
     *      If the NNTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send NNTP reply code 400.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     * @since 3.0
     */
    public Iterable<NewsgroupInfo> iterateNewsgroups() throws IOException {
        return new NewsgroupIterator(iterateNewsgroupListing());
    }

    /**
     * List the newsgroups that match a given pattern.
     * Uses the "LIST ACTIVE" command.
     * <p>
     * @param wildmat a pseudo-regex pattern (cf. RFC 2980)
     * @return An array of NewsgroupInfo instances containing the information
     *    for each newsgroup served by the NNTP server corresponding to the
     *    supplied pattern.   If no such newsgroups are served, a zero length
     *    array will be returned.  If the command fails, null will be returned.
     * @throws IOException on error
     * @see #iterateNewsgroupListing(String)
     * @see #iterateNewsgroups(String)
     */
    public NewsgroupInfo[] listNewsgroups(final String wildmat) throws IOException
    {
        if(!NNTPReply.isPositiveCompletion(listActive(wildmat))) {
            return null;
        }
        return readNewsgroupListing();
    }


    /**
     * List the newsgroups that match a given pattern.
     * Uses the "LIST ACTIVE" command.
     * <p>
     * @param wildmat a pseudo-regex pattern (cf. RFC 2980)
     * @return An iterable of Strings containing the raw information
     *    for each newsgroup served by the NNTP server corresponding to the
     *    supplied pattern.   If no such newsgroups are served, no entries
     *    will be returned.
     * @throws IOException on error
     * @since 3.0
     */
    public Iterable<String> iterateNewsgroupListing(final String wildmat) throws IOException {
        if(NNTPReply.isPositiveCompletion(listActive(wildmat))) {
            return new ReplyIterator(_reader_);
        }
        throw new IOException("LIST ACTIVE "+wildmat+" command failed: "+getReplyString());
    }

    /**
     * List the newsgroups that match a given pattern.
     * Uses the "LIST ACTIVE" command.
     * <p>
     * @param wildmat a pseudo-regex pattern (cf. RFC 2980)
     * @return An iterable NewsgroupInfo instances containing the information
     *    for each newsgroup served by the NNTP server corresponding to the
     *    supplied pattern.   If no such newsgroups are served, no entries
     *    will be returned.
     * @throws IOException on error
     * @since 3.0
     */
    public Iterable<NewsgroupInfo> iterateNewsgroups(final String wildmat) throws IOException {
        return new NewsgroupIterator(iterateNewsgroupListing(wildmat));
    }

    /**
     * List all new newsgroups added to the NNTP server since a particular
     * date subject to the conditions of the specified query.  If no new
     * newsgroups were added, a zero length array will be returned.  If the
     * command fails, null will be returned.
     * This uses the "NEWGROUPS" command.
     * <p>
     * @param query  The query restricting how to search for new newsgroups.
     * @return An array of NewsgroupInfo instances containing the information
     *    for each new newsgroup added to the NNTP server.   If no newsgroups
     *    were added, a zero length array will be returned.  If the command
     *    fails, null will be returned.
     * @throws NNTPConnectionClosedException
     *      If the NNTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send NNTP reply code 400.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     * @see #iterateNewNewsgroups(NewGroupsOrNewsQuery)
     * @see #iterateNewNewsgroupListing(NewGroupsOrNewsQuery)
     */
    public NewsgroupInfo[] listNewNewsgroups(final NewGroupsOrNewsQuery query)
    throws IOException
    {
        if (!NNTPReply.isPositiveCompletion(newgroups(
                                                query.getDate(), query.getTime(),
                                                query.isGMT(), query.getDistributions())))
        {
            return null;
        }

        return readNewsgroupListing();
    }

    /**
     * List all new newsgroups added to the NNTP server since a particular
     * date subject to the conditions of the specified query.  If no new
     * newsgroups were added, no entries will be returned.
     * This uses the "NEWGROUPS" command.
     * <p>
     * @param query  The query restricting how to search for new newsgroups.
     * @return An iterable of Strings containing the raw information
     *    for each new newsgroup added to the NNTP server.   If no newsgroups
     *    were added, no entries will be returned.
     * @throws NNTPConnectionClosedException
     *      If the NNTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send NNTP reply code 400.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     * @since 3.0
     */
    public Iterable<String> iterateNewNewsgroupListing(final NewGroupsOrNewsQuery query) throws IOException {
        if (NNTPReply.isPositiveCompletion(newgroups(
                query.getDate(), query.getTime(),
                query.isGMT(), query.getDistributions()))) {
            return new ReplyIterator(_reader_);
        }
        throw new IOException("NEWGROUPS command failed: "+getReplyString());
    }

    /**
     * List all new newsgroups added to the NNTP server since a particular
     * date subject to the conditions of the specified query.  If no new
     * newsgroups were added, no entries will be returned.
     * This uses the "NEWGROUPS" command.
     * <p>
     * @param query  The query restricting how to search for new newsgroups.
     * @return An iterable of NewsgroupInfo instances containing the information
     *    for each new newsgroup added to the NNTP server.   If no newsgroups
     *    were added, no entries will be returned.
     * @throws NNTPConnectionClosedException
     *      If the NNTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send NNTP reply code 400.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     * @since 3.0
     */
    public Iterable<NewsgroupInfo> iterateNewNewsgroups(final NewGroupsOrNewsQuery query) throws IOException {
        return new NewsgroupIterator(iterateNewNewsgroupListing(query));
    }

    /**
     * List all new articles added to the NNTP server since a particular
     * date subject to the conditions of the specified query.  If no new
     * new news is found, a zero length array will be returned.  If the
     * command fails, null will be returned.  You must add at least one
     * newsgroup to the query, else the command will fail.  Each String
     * in the returned array is a unique message identifier including the
     * enclosing &lt; and &gt;.
     * This uses the "NEWNEWS" command.
     * <p>
     * @param query  The query restricting how to search for new news.  You
     *    must add at least one newsgroup to the query.
     * @return An array of String instances containing the unique message
     *    identifiers for each new article added to the NNTP server.  If no
     *    new news is found, a zero length array will be returned.  If the
     *    command fails, null will be returned.
     * @throws NNTPConnectionClosedException
     *      If the NNTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send NNTP reply code 400.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     *
     * @see #iterateNewNews(NewGroupsOrNewsQuery)
     */
    public String[] listNewNews(final NewGroupsOrNewsQuery query)
    throws IOException
    {
        if (!NNTPReply.isPositiveCompletion(newnews(query.getNewsgroups(), query.getDate(), query.getTime(),
                query.isGMT(), query.getDistributions()))) {
            return null;
        }

        final Vector<String> list = new Vector<>();
        try (final BufferedReader reader = new DotTerminatedMessageReader(_reader_)) {

            String line;
            while ((line = reader.readLine()) != null) {
                list.addElement(line);
            }
        }

        final int size = list.size();
        if (size < 1) {
            return NetConstants.EMPTY_STRING_ARRAY;
        }

        final String[] result = new String[size];
        list.copyInto(result);

        return result;
    }

    /**
     * List all new articles added to the NNTP server since a particular
     * date subject to the conditions of the specified query.  If no new
     * new news is found, no entries will be returned.
     * This uses the "NEWNEWS" command.
     * You must add at least one newsgroup to the query, else the command will fail.
     * Each String which is returned is a unique message identifier including the
     * enclosing &lt; and &gt;.
     * <p>
     * @param query  The query restricting how to search for new news.  You
     *    must add at least one newsgroup to the query.
     * @return An iterator of String instances containing the unique message
     *    identifiers for each new article added to the NNTP server.  If no
     *    new news is found, no strings will be returned.
     * @throws NNTPConnectionClosedException
     *      If the NNTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send NNTP reply code 400.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     * @since 3.0
     */
    public Iterable<String> iterateNewNews(final NewGroupsOrNewsQuery query) throws IOException {
        if (NNTPReply.isPositiveCompletion(newnews(
                query.getNewsgroups(), query.getDate(), query.getTime(),
                query.isGMT(), query.getDistributions()))) {
            return new ReplyIterator(_reader_);
        }
        throw new IOException("NEWNEWS command failed: "+getReplyString());
    }

    /**
     * There are a few NNTPClient methods that do not complete the
     * entire sequence of NNTP commands to complete a transaction.  These
     * commands require some action by the programmer after the reception
     * of a positive preliminary command.  After the programmer's code
     * completes its actions, it must call this method to receive
     * the completion reply from the server and verify the success of the
     * entire transaction.
     * <p>
     * For example
     * <pre>
     * writer = client.postArticle();
     * if(writer == null) // failure
     *   return false;
     * header = new SimpleNNTPHeader("foobar@foo.com", "Just testing");
     * header.addNewsgroup("alt.test");
     * writer.write(header.toString());
     * writer.write("This is just a test");
     * writer.close();
     * if(!client.completePendingCommand()) // failure
     *   return false;
     * </pre>
     * <p>
     * @return True if successfully completed, false if not.
     * @throws NNTPConnectionClosedException
     *      If the NNTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send NNTP reply code 400.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean completePendingCommand() throws IOException
    {
        return NNTPReply.isPositiveCompletion(getReply());
    }

    /**
     * Post an article to the NNTP server.  This method returns a
     * DotTerminatedMessageWriter instance to which the article can be
     * written.  Null is returned if the posting attempt fails.  You
     * should check {@link NNTP#isAllowedToPost isAllowedToPost() }
     *  before trying to post.  However, a posting
     * attempt can fail due to malformed headers.
     * <p>
     * You must not issue any commands to the NNTP server (i.e., call any
     * (other methods) until you finish writing to the returned Writer
     * instance and close it.  The NNTP protocol uses the same stream for
     * issuing commands as it does for returning results.  Therefore the
     * returned Writer actually writes directly to the NNTP connection.
     * After you close the writer, you can execute new commands.  If you
     * do not follow these requirements your program will not work properly.
     * <p>
     * Different NNTP servers will require different header formats, but
     * you can use the provided
     * {@link org.apache.commons.net.nntp.SimpleNNTPHeader}
     * class to construct the bare minimum acceptable header for most
     * news readers.  To construct more complicated headers you should
     * refer to RFC 822.  When the Java Mail API is finalized, you will be
     * able to use it to compose fully compliant Internet text messages.
     * The DotTerminatedMessageWriter takes care of doubling line-leading
     * dots and ending the message with a single dot upon closing, so all
     * you have to worry about is writing the header and the message.
     * <p>
     * Upon closing the returned Writer, you need to call
     * {@link #completePendingCommand  completePendingCommand() }
     * to finalize the posting and verify its success or failure from
     * the server reply.
     * <p>
     * @return A DotTerminatedMessageWriter to which the article (including
     *      header) can be written.  Returns null if the command fails.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */

    public Writer postArticle() throws IOException
    {
        if (!NNTPReply.isPositiveIntermediate(post())) {
            return null;
        }

        return new DotTerminatedMessageWriter(_writer_);
    }


    public Writer forwardArticle(final String articleId) throws IOException
    {
        if (!NNTPReply.isPositiveIntermediate(ihave(articleId))) {
            return null;
        }

        return new DotTerminatedMessageWriter(_writer_);
    }


    /**
     * Logs out of the news server gracefully by sending the QUIT command.
     * However, you must still disconnect from the server before you can open
     * a new connection.
     * <p>
     * @return True if successfully completed, false if not.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean logout() throws IOException
    {
        return NNTPReply.isPositiveCompletion(quit());
    }


    /**
     * Log into a news server by sending the AUTHINFO USER/AUTHINFO
     * PASS command sequence. This is usually sent in response to a
     * 480 reply code from the NNTP server.
     * <p>
     * @param username a valid username
     * @param password the corresponding password
     * @return True for successful login, false for a failure
     * @throws IOException on error
     */
    public boolean authenticate(final String username, final String password)
        throws IOException
    {
        int replyCode = authinfoUser(username);

        if (replyCode == NNTPReply.MORE_AUTH_INFO_REQUIRED)
            {
                replyCode = authinfoPass(password);

                if (replyCode == NNTPReply.AUTHENTICATION_ACCEPTED)
                    {
                        this._isAllowedToPost = true;
                        return true;
                    }
            }
        return false;
    }

    /**
     * Private implementation of XOVER functionality.
     *
     * See {@link NNTP#xover}
     * for legal agument formats. Alternatively, read RFC 2980 :-)
     * <p>
     * @param articleRange
     * @return Returns a DotTerminatedMessageReader if successful, null
     *         otherwise
     * @throws IOException
     */
    private BufferedReader retrieveArticleInfo(final String articleRange)
        throws IOException
    {
        if (!NNTPReply.isPositiveCompletion(xover(articleRange))) {
            return null;
        }

        return new DotTerminatedMessageReader(_reader_);
    }

    /**
     * Return article headers for a specified post.
     * <p>
     * @param articleNumber the article to retrieve headers for
     * @return a DotTerminatedReader if successful, null otherwise
     * @throws IOException on error
     */
    public BufferedReader retrieveArticleInfo(final long articleNumber) throws IOException
    {
        return retrieveArticleInfo(Long.toString(articleNumber));
    }

    /**
     * Return article headers for all articles between lowArticleNumber
     * and highArticleNumber, inclusively. Uses the XOVER command.
     * <p>
     * @param lowArticleNumber low number
     * @param highArticleNumber high number
     * @return a DotTerminatedReader if successful, null otherwise
     * @throws IOException on error
     */
    public BufferedReader retrieveArticleInfo(final long lowArticleNumber,
            final long highArticleNumber)
        throws IOException
    {
        return
            retrieveArticleInfo(lowArticleNumber + "-" +
                                             highArticleNumber);
    }

    /**
     * Return article headers for all articles between lowArticleNumber
     * and highArticleNumber, inclusively, using the XOVER command.
     * <p>
     * @param lowArticleNumber low
     * @param highArticleNumber high
     * @return an Iterable of Articles
     * @throws IOException if the command failed
     * @since 3.0
     */
    public Iterable<Article> iterateArticleInfo(final long lowArticleNumber, final long highArticleNumber)
        throws IOException
    {
        final BufferedReader info = retrieveArticleInfo(lowArticleNumber,highArticleNumber);
        if (info == null) {
            throw new IOException("XOVER command failed: "+getReplyString());
        }
        // N.B. info is already DotTerminated, so don't rewrap
        return new ArticleIterator(new ReplyIterator(info, false));
    }

    /**
     * Private implementation of XHDR functionality.
     *
     * See {@link NNTP#xhdr}
     * for legal agument formats. Alternatively, read RFC 1036.
     * <p>
     * @param header
     * @param articleRange
     * @return Returns a DotTerminatedMessageReader if successful, null
     *         otherwise
     * @throws IOException
     */
    private BufferedReader retrieveHeader(final String header, final String articleRange)
        throws IOException
    {
        if (!NNTPReply.isPositiveCompletion(xhdr(header, articleRange))) {
            return null;
        }

        return new DotTerminatedMessageReader(_reader_);
    }

    /**
     * Return an article header for a specified post.
     * <p>
     * @param header the header to retrieve
     * @param articleNumber the article to retrieve the header for
     * @return a DotTerminatedReader if successful, null otherwise
     * @throws IOException on error
     */
    public BufferedReader retrieveHeader(final String header, final long articleNumber)
        throws IOException
    {
        return retrieveHeader(header, Long.toString(articleNumber));
    }

    /**
     * Return an article header for all articles between lowArticleNumber
     * and highArticleNumber, inclusively.
     * <p>
     * @param header the header
     * @param lowArticleNumber to fetch
     * @param highArticleNumber to fetch
     * @return a DotTerminatedReader if successful, null otherwise
     * @throws IOException on error
     */
    public BufferedReader retrieveHeader(final String header, final long lowArticleNumber,
                                 final long highArticleNumber)
        throws IOException
    {
        return
            retrieveHeader(header,lowArticleNumber + "-" + highArticleNumber);
    }





    // DEPRECATED METHODS - for API compatibility only - DO NOT USE
    // ============================================================



    /**
     * @param header the header
     * @param lowArticleNumber to fetch
     * @param highArticleNumber to fetch
     * @return a DotTerminatedReader if successful, null otherwise
     * @throws IOException on error
     * @deprecated 3.0 use {@link #retrieveHeader(String, long, long)} instead
     */
    @Deprecated
    public Reader retrieveHeader(final String header, final int lowArticleNumber, final int highArticleNumber)
        throws IOException
    {
        return retrieveHeader(header, (long) lowArticleNumber, (long) highArticleNumber);
    }

    /**
     * @param lowArticleNumber to fetch
     * @param highArticleNumber to fetch
     * @return a DotTerminatedReader if successful, null otherwise
     * @throws IOException on error
     * @deprecated 3.0 use {@link #retrieveArticleInfo(long, long)} instead
     */
    @Deprecated
    public Reader retrieveArticleInfo(final int lowArticleNumber, final int highArticleNumber) throws IOException {
        return retrieveArticleInfo((long) lowArticleNumber, (long) highArticleNumber);
    }

    /**
     * @param a tba
     * @param b  tba
     * @return  tba
     * @throws IOException tba
     * @deprecated 3.0 use {@link #retrieveHeader(String, long)} instead
     */
    @Deprecated
    public Reader retrieveHeader(final String a, final int b) throws IOException {
        return retrieveHeader(a, (long) b);
    }

    /**
     * @param a  tba
     * @param ap  tba
     * @return  tba
     * @throws IOException tba
     * @deprecated 3.0 use {@link #selectArticle(long, ArticleInfo)} instead
     */
    @Deprecated
    public boolean selectArticle(final int a, final ArticlePointer ap) throws IOException {
        final ArticleInfo ai =  ap2ai(ap);
        final boolean b = selectArticle(a, ai);
        ai2ap(ai, ap);
        return b;
    }

    /**
     * @param lowArticleNumber to fetch
     * @return a DotTerminatedReader if successful, null otherwise
     * @throws IOException  tba
     * @deprecated 3.0 use {@link #retrieveArticleInfo(long)} instead
     */
    @Deprecated
    public Reader retrieveArticleInfo(final int lowArticleNumber) throws IOException {
        return retrieveArticleInfo((long) lowArticleNumber);
    }

    /**
     * @param a  tba
     * @return  tba
     * @throws IOException  tba
     * @deprecated 3.0 use {@link #selectArticle(long)} instead
     */
    @Deprecated
    public boolean selectArticle(final int a) throws IOException {
        return selectArticle((long) a);
    }

    /**
     * @param a  tba
     * @return  tba
     * @throws IOException  tba
     * @deprecated 3.0 use {@link #retrieveArticleHeader(long)} instead
     */
    @Deprecated
    public Reader retrieveArticleHeader(final int a) throws IOException {
        return retrieveArticleHeader((long) a);
    }

    /**
     * @param a  tba
     * @param ap  tba
     * @return  tba
     * @throws IOException  tba
     * @deprecated 3.0 use {@link #retrieveArticleHeader(long, ArticleInfo)} instead
     */
    @Deprecated
    public Reader retrieveArticleHeader(final int a, final ArticlePointer ap) throws IOException {
        final ArticleInfo ai =  ap2ai(ap);
        final Reader rdr = retrieveArticleHeader(a, ai);
        ai2ap(ai, ap);
        return rdr;
    }

    /**
     * @param a  tba
     * @return  tba
     * @throws IOException  tba
     * @deprecated 3.0 use {@link #retrieveArticleBody(long)} instead
     */
    @Deprecated
    public Reader retrieveArticleBody(final int a) throws IOException {
        return retrieveArticleBody((long) a);
    }

    /**
     * @param articleNumber  The number of the the article to retrieve.
     * @param pointer A parameter through which to return the article's number and unique id
     * @return A DotTerminatedMessageReader instance from which the article
     *         can be read.  null if the article does not exist.
     * @throws IOException on error
     * @deprecated 3.0 use {@link #retrieveArticle(long, ArticleInfo)} instead
     */
    @Deprecated
    public Reader retrieveArticle(final int articleNumber, final ArticlePointer pointer) throws IOException {
        final ArticleInfo ai =  ap2ai(pointer);
        final Reader rdr = retrieveArticle(articleNumber, ai);
        ai2ap(ai, pointer);
        return rdr;
    }

    /**
     * @param articleNumber The number of the the article to retrieve
     * @return A DotTerminatedMessageReader instance from which the article
     *         can be read.  null if the article does not exist.
     * @throws IOException on error
     * @deprecated 3.0 use {@link #retrieveArticle(long)} instead
     */
    @Deprecated
    public Reader retrieveArticle(final int articleNumber) throws IOException {
        return retrieveArticle((long) articleNumber);
    }

    /**
     * @param a  tba
     * @param ap  tba
     * @return  tba
     * @throws IOException  tba
     * @deprecated 3.0 use {@link #retrieveArticleBody(long, ArticleInfo)} instead
     */
    @Deprecated
    public Reader retrieveArticleBody(final int a, final ArticlePointer ap) throws IOException {
        final ArticleInfo ai =  ap2ai(ap);
        final Reader rdr = retrieveArticleBody(a, ai);
        ai2ap(ai, ap);
        return rdr;
    }

    /**
     * @param articleId The unique article identifier of the article to retrieve
     * @param pointer A parameter through which to return the article's number and unique id
     * @deprecated 3.0 use {@link #retrieveArticle(String, ArticleInfo)} instead
     * @return A DotTerminatedMessageReader instance from which the article can be read.
     * null if the article does not exist.
     * @throws IOException on error
     */
    @Deprecated
    public Reader retrieveArticle(final String articleId, final ArticlePointer pointer) throws IOException {
        final ArticleInfo ai =  ap2ai(pointer);
        final Reader rdr = retrieveArticle(articleId, ai);
        ai2ap(ai, pointer);
        return rdr;
    }

    /**
     * @param articleId The unique article identifier of the article to retrieve
     * @param pointer A parameter through which to return the article's number and unique id
     * @return A DotTerminatedMessageReader instance from which the article
     *         body can be read.  null if the article does not exist.
     * @throws IOException on error
     * @deprecated 3.0 use {@link #retrieveArticleBody(String, ArticleInfo)} instead
     */
    @Deprecated
    public Reader retrieveArticleBody(final String articleId, final ArticlePointer pointer) throws IOException {
        final ArticleInfo ai =  ap2ai(pointer);
        final Reader rdr = retrieveArticleBody(articleId, ai);
        ai2ap(ai, pointer);
        return rdr;
    }

    /**
     * @param articleId The unique article identifier of the article to retrieve
     * @param pointer A parameter through which to return the article's number and unique id
     * @return A DotTerminatedMessageReader instance from which the article
     *         body can be read.  null if the article does not exist.
     * @throws IOException on error
     * @deprecated 3.0 use {@link #retrieveArticleHeader(String, ArticleInfo)} instead
     */
    @Deprecated
    public Reader retrieveArticleHeader(final String articleId, final ArticlePointer pointer) throws IOException {
        final ArticleInfo ai =  ap2ai(pointer);
        final Reader rdr = retrieveArticleHeader(articleId, ai);
        ai2ap(ai, pointer);
        return rdr;
    }

    /**
     * @param articleId The unique article identifier of the article to retrieve
     * @param pointer A parameter through which to return the article's number and unique id
     * @return A DotTerminatedMessageReader instance from which the article
     *         body can be read.  null if the article does not exist.
     * @throws IOException on error
     * @deprecated 3.0 use {@link #selectArticle(String, ArticleInfo)} instead
     */
    @Deprecated
    public boolean selectArticle(final String articleId, final ArticlePointer pointer) throws IOException {
        final ArticleInfo ai =  ap2ai(pointer);
        final boolean b = selectArticle(articleId, ai);
        ai2ap(ai, pointer);
        return b;

    }

    /**
     * @param pointer A parameter through which to return the article's number and unique id
     * @return True if successful, false if not.
     * @throws IOException on error
     * @deprecated 3.0 use {@link #selectArticle(ArticleInfo)} instead
     */
    @Deprecated
    public boolean selectArticle(final ArticlePointer pointer) throws IOException {
        final ArticleInfo ai =  ap2ai(pointer);
        final boolean b = selectArticle(ai);
        ai2ap(ai, pointer);
        return b;

    }

    /**
     * @param pointer A parameter through which to return the article's number and unique id
     * @return True if successful, false if not.
     * @throws IOException on error
     * @deprecated 3.0 use {@link #selectNextArticle(ArticleInfo)} instead
     */
    @Deprecated
    public boolean selectNextArticle(final ArticlePointer pointer) throws IOException {
        final ArticleInfo ai =  ap2ai(pointer);
        final boolean b = selectNextArticle(ai);
        ai2ap(ai, pointer);
        return b;

    }

    /**
     * @param pointer A parameter through which to return the article's number and unique id
     * @return True if successful, false if not.
     * @throws IOException on error
     * @deprecated 3.0 use {@link #selectPreviousArticle(ArticleInfo)} instead
     */
    @Deprecated
    public boolean selectPreviousArticle(final ArticlePointer pointer) throws IOException {
        final ArticleInfo ai =  ap2ai(pointer);
        final boolean b = selectPreviousArticle(ai);
        ai2ap(ai, pointer);
        return b;
    }

   // Helper methods

    private ArticleInfo ap2ai(@SuppressWarnings("deprecation") final ArticlePointer ap) {
        if (ap == null) {
            return null;
        }
        final ArticleInfo ai = new ArticleInfo();
        return ai;
    }

    @SuppressWarnings("deprecation")
    private void ai2ap(final ArticleInfo ai, final ArticlePointer ap){
        if (ap != null) { // ai cannot be null
            ap.articleId = ai.articleId;
            ap.articleNumber = (int) ai.articleNumber;
        }
    }
}

org/apache/commons/net/nntp/NNTPClient.java

 

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