alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

What this is

This file is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Other links

The source code

/*
 * Copyright 2001-2004 The Apache Software Foundation
 *
 * Licensed 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.StringTokenizer;
import java.util.Vector;
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.MalformedServerReplyException;

/***
 * NNTPClient encapsulates all the functionality necessary to post and
 * retrieve articles from an NNTP server.  As with all classes derived
 * from  SocketClient ,
 * you must first connect to the server with
 *  connect 
 * before doing anything, and finally
 *  disconnect() 
 * after you're completely finished interacting with the server.
 * Remember that the
 * 
 * isAllowedToPost() method is defined in
 *  NNTP .
 * 

* 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 * * NNTPReply.SERVICE_DISCONTINUED response to a command. * When that occurs, the NNTP class method encountering that reply will throw * an * NNTPConnectionClosedException . * NNTPConectionClosedException * is a subclass of IOException 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 IOException * catch block. When you encounter an * * NNTPConnectionClosedException , you must disconnect the connection with * disconnect() * to properly clean up the * system resources used by NNTP. Before disconnecting, you may check the * last reply code and text with * getReplyCode and * getReplyString . *

* 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 * * 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. *

*

* @author Daniel F. Savarese * @author Rory Winston * @author Ted Wise * @see NNTP * @see NNTPConnectionClosedException * @see org.apache.commons.net.MalformedServerReplyException ***/ public class NNTPClient extends NNTP { private void __parseArticlePointer(String reply, ArticlePointer pointer) throws MalformedServerReplyException { StringTokenizer tokenizer; // Do loop is a kluge to simulate goto do { tokenizer = new StringTokenizer(reply); if (tokenizer.countTokens() < 3) break; // Skip numeric response value tokenizer.nextToken(); // Get article number try { pointer.articleNumber = Integer.parseInt(tokenizer.nextToken()); } catch (NumberFormatException e) { break; } // Get article id pointer.articleId = tokenizer.nextToken(); return ; } while (false); throw new MalformedServerReplyException( "Could not parse article pointer.\nServer reply: " + reply); } private void __parseGroupReply(String reply, NewsgroupInfo info) throws MalformedServerReplyException { String count, first, last; StringTokenizer tokenizer; // Do loop is a kluge to simulate goto do { tokenizer = new StringTokenizer(reply); if (tokenizer.countTokens() < 5) break; // Skip numeric response value tokenizer.nextToken(); // Get estimated article count count = tokenizer.nextToken(); // Get first article number first = tokenizer.nextToken(); // Get last article number last = tokenizer.nextToken(); // Get newsgroup name info._setNewsgroup(tokenizer.nextToken()); try { info._setArticleCount(Integer.parseInt(count)); info._setFirstArticle(Integer.parseInt(first)); info._setLastArticle(Integer.parseInt(last)); } catch (NumberFormatException e) { break; } info._setPostingPermission(NewsgroupInfo.UNKNOWN_POSTING_PERMISSION); return ; } while (false); throw new MalformedServerReplyException( "Could not parse newsgroup info.\nServer reply: " + reply); } private NewsgroupInfo __parseNewsgroupListEntry(String entry) { NewsgroupInfo result; StringTokenizer tokenizer; int lastNum, firstNum; String last, first, permission; result = new NewsgroupInfo(); tokenizer = new StringTokenizer(entry); if (tokenizer.countTokens() < 4) return null; result._setNewsgroup(tokenizer.nextToken()); last = tokenizer.nextToken(); first = tokenizer.nextToken(); permission = tokenizer.nextToken(); try { lastNum = Integer.parseInt(last); firstNum = Integer.parseInt(first); result._setFirstArticle(firstNum); result._setLastArticle(lastNum); result._setArticleCount(lastNum - firstNum + 1); } catch (NumberFormatException e) { return null; } switch (permission.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; } private NewsgroupInfo[] __readNewsgroupListing() throws IOException { int size; String line; Vector list; BufferedReader reader; NewsgroupInfo tmp, info[]; reader = new BufferedReader(new DotTerminatedMessageReader(_reader_)); // Start of with a big vector because we may be reading a very large // amount of groups. list = new Vector(2048); while ((line = reader.readLine()) != null) { tmp = __parseNewsgroupListEntry(line); if (tmp != null) list.addElement(tmp); else throw new MalformedServerReplyException(line); } if ((size = list.size()) < 1) return new NewsgroupInfo[0]; info = new NewsgroupInfo[size]; list.copyInto(info); return info; } private Reader __retrieve(int command, String articleId, ArticlePointer pointer) throws IOException { Reader reader; 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); reader = new DotTerminatedMessageReader(_reader_); return reader; } private Reader __retrieve(int command, int articleNumber, ArticlePointer pointer) throws IOException { Reader reader; if (!NNTPReply.isPositiveCompletion(sendCommand(command, Integer.toString(articleNumber)))) return null; if (pointer != null) __parseArticlePointer(getReplyString(), pointer); reader = new DotTerminatedMessageReader(_reader_); return reader; } /*** * Retrieves an article from the NNTP server. The article is referenced * by its unique article identifier (including the enclosing < and >). * The article number and identifier contained in the server reply * are returned through an ArticlePointer. The articleId * field of the ArticlePointer cannot always be trusted because some * NNTP servers do not correctly follow the RFC 977 reply format. *

* A DotTerminatedMessageReader is returned from which the article can * be read. If the article does not exist, null is returned. *

* 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 * Reader instance. * The NNTP protocol uses the same stream for issuing commands as it does * for returning results. Therefore the returned Reader 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. *

* @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 * be read. null if the article does not exist. * @exception 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. * @exception IOException If an I/O error occurs while either sending a * command to the server or receiving a reply from the server. ***/ public Reader retrieveArticle(String articleId, ArticlePointer pointer) throws IOException { return __retrieve(NNTPCommand.ARTICLE, articleId, pointer); } /*** Same as retrieveArticle(articleId, null) ***/ public Reader retrieveArticle(String articleId) throws IOException { return retrieveArticle(articleId, null); } /*** Same as retrieveArticle(null) ***/ public Reader retrieveArticle() throws IOException { return retrieveArticle(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 ArticlePointer. The articleId * field of the ArticlePointer cannot always be trusted because some * NNTP servers do not correctly follow the RFC 977 reply format. *

* A DotTerminatedMessageReader is returned from which the article can * be read. If the article does not exist, null is returned. *

* 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 * Reader instance. * The NNTP protocol uses the same stream for issuing commands as it does * for returning results. Therefore the returned Reader 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. *

* @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 * be read. null if the article does not exist. * @exception 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. * @exception IOException If an I/O error occurs while either sending a * command to the server or receiving a reply from the server. ***/ public Reader retrieveArticle(int articleNumber, ArticlePointer pointer) throws IOException { return __retrieve(NNTPCommand.ARTICLE, articleNumber, pointer); } /*** Same as retrieveArticle(articleNumber, null) ***/ public Reader retrieveArticle(int 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 < and >). * The article number and identifier contained in the server reply * are returned through an ArticlePointer. The articleId * field of the ArticlePointer cannot always be trusted because some * NNTP servers do not correctly follow the RFC 977 reply format. *

* A DotTerminatedMessageReader is returned from which the article can * be read. If the article does not exist, null is returned. *

* 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 * Reader instance. * The NNTP protocol uses the same stream for issuing commands as it does * for returning results. Therefore the returned Reader 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. *

* @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. * @exception 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. * @exception IOException If an I/O error occurs while either sending a * command to the server or receiving a reply from the server. ***/ public Reader retrieveArticleHeader(String articleId, ArticlePointer pointer) throws IOException { return __retrieve(NNTPCommand.HEAD, articleId, pointer); } /*** Same as retrieveArticleHeader(articleId, null) ***/ public Reader retrieveArticleHeader(String articleId) throws IOException { return retrieveArticleHeader(articleId, null); } /*** Same as retrieveArticleHeader(null) ***/ public Reader retrieveArticleHeader() throws IOException { return retrieveArticleHeader(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 ArticlePointer. The articleId * field of the ArticlePointer cannot always be trusted because some * NNTP servers do not correctly follow the RFC 977 reply format. *

* A DotTerminatedMessageReader is returned from which the article can * be read. If the article does not exist, null is returned. *

* 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 * Reader instance. * The NNTP protocol uses the same stream for issuing commands as it does * for returning results. Therefore the returned Reader 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. *

* @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. * @exception 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. * @exception IOException If an I/O error occurs while either sending a * command to the server or receiving a reply from the server. ***/ public Reader retrieveArticleHeader(int articleNumber, ArticlePointer pointer) throws IOException { return __retrieve(NNTPCommand.HEAD, articleNumber, pointer); } /*** Same as retrieveArticleHeader(articleNumber, null) ***/ public Reader retrieveArticleHeader(int 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 < and >). * The article number and identifier contained in the server reply * are returned through an ArticlePointer. The articleId * field of the ArticlePointer cannot always be trusted because some * NNTP servers do not correctly follow the RFC 977 reply format. *

* A DotTerminatedMessageReader is returned from which the article can * be read. If the article does not exist, null is returned. *

* 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 * Reader instance. * The NNTP protocol uses the same stream for issuing commands as it does * for returning results. Therefore the returned Reader 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. *

* @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. * @exception 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. * @exception IOException If an I/O error occurs while either sending a * command to the server or receiving a reply from the server. ***/ public Reader retrieveArticleBody(String articleId, ArticlePointer pointer) throws IOException { return __retrieve(NNTPCommand.BODY, articleId, pointer); } /*** Same as retrieveArticleBody(articleId, null) ***/ public Reader retrieveArticleBody(String articleId) throws IOException { return retrieveArticleBody(articleId, null); } /*** Same as retrieveArticleBody(null) ***/ 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 ArticlePointer. The articleId * field of the ArticlePointer cannot always be trusted because some * NNTP servers do not correctly follow the RFC 977 reply format. *

* A DotTerminatedMessageReader is returned from which the article can * be read. If the article does not exist, null is returned. *

* 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 * Reader instance. * The NNTP protocol uses the same stream for issuing commands as it does * for returning results. Therefore the returned Reader 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. *

* @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. * @exception 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. * @exception IOException If an I/O error occurs while either sending a * command to the server or receiving a reply from the server. ***/ public Reader retrieveArticleBody(int articleNumber, ArticlePointer pointer) throws IOException { return __retrieve(NNTPCommand.BODY, articleNumber, pointer); } /*** Same as retrieveArticleBody(articleNumber, null) ***/ public Reader retrieveArticleBody(int 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. *

* @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. * @exception 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. * @exception 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(String newsgroup, NewsgroupInfo info) throws IOException { if (!NNTPReply.isPositiveCompletion(group(newsgroup))) return false; if (info != null) __parseGroupReply(getReplyString(), info); return true; } /*** Same as selectNewsgroup(newsgroup, null) ***/ public boolean selectNewsgroup(String newsgroup) throws IOException { return selectNewsgroup(newsgroup, null); } /*** * List the command help from the server. *

* @return The sever help information. * @exception 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. * @exception 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 { StringWriter help; Reader reader; if (!NNTPReply.isInformational(help())) return null; help = new StringWriter(); reader = new DotTerminatedMessageReader(_reader_); Util.copyReader(reader, help); reader.close(); help.close(); return help.toString(); } /*** * Select an article by its unique identifier (including enclosing * < and >) 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. *

* @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. * @exception 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. * @exception 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(String articleId, ArticlePointer 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 selectArticle(articleId, null) ***/ public boolean selectArticle(String articleId) throws IOException { return selectArticle(articleId, null); } /**** * Same as selectArticle(null, articleId) . Useful * for retrieving the current article number. ***/ public boolean selectArticle(ArticlePointer 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. *

* @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. * @exception 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. * @exception 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(int articleNumber, ArticlePointer pointer) throws IOException { if (!NNTPReply.isPositiveCompletion(stat(articleNumber))) return false; if (pointer != null) __parseArticlePointer(getReplyString(), pointer); return true; } /*** Same as selectArticle(articleNumber, null) ***/ public boolean selectArticle(int 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 * selectArticle(pointer.articleNumber, pointer) immediately * afterward. *

* @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). * @exception 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. * @exception 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(ArticlePointer pointer) throws IOException { if (!NNTPReply.isPositiveCompletion(last())) return false; if (pointer != null) __parseArticlePointer(getReplyString(), pointer); return true; } /*** Same as selectPreviousArticle(null) ***/ public boolean selectPreviousArticle() throws IOException { return selectPreviousArticle(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 * selectArticle(pointer.articleNumber, pointer) immediately * afterward. *

* @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). * @exception 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. * @exception 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(ArticlePointer pointer) throws IOException { if (!NNTPReply.isPositiveCompletion(next())) return false; if (pointer != null) __parseArticlePointer(getReplyString(), pointer); return true; } /*** Same as selectNextArticle(null) ***/ public boolean selectNextArticle() throws IOException { return selectNextArticle(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. *

* @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. * @exception 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. * @exception IOException If an I/O error occurs while either sending a * command to the server or receiving a reply from the server. ***/ public NewsgroupInfo[] listNewsgroups() throws IOException { if (!NNTPReply.isPositiveCompletion(list())) return null; return __readNewsgroupListing(); } /** * An overloaded listNewsgroups() command that allows us to * specify with a pattern what groups we want to list. Wraps the * LIST ACTIVE command. *

* @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 */ public NewsgroupInfo[] listNewsgroups(String wildmat) throws IOException { if(!NNTPReply.isPositiveCompletion(listActive(wildmat))) 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, a zero length array will be returned. If the * command fails, null will be returned. *

* @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. * @exception 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. * @exception IOException If an I/O error occurs while either sending a * command to the server or receiving a reply from the server. ***/ public NewsgroupInfo[] listNewNewsgroups(NewGroupsOrNewsQuery query) throws IOException { if (!NNTPReply.isPositiveCompletion(newgroups( query.getDate(), query.getTime(), query.isGMT(), query.getDistributions()))) return null; return __readNewsgroupListing(); } /*** * 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 < and >. *

* @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. * @exception 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. * @exception IOException If an I/O error occurs while either sending a * command to the server or receiving a reply from the server. ***/ public String[] listNewNews(NewGroupsOrNewsQuery query) throws IOException { int size; String line; Vector list; String[] result; BufferedReader reader; if (!NNTPReply.isPositiveCompletion(newnews( query.getNewsgroups(), query.getDate(), query.getTime(), query.isGMT(), query.getDistributions()))) return null; list = new Vector(); reader = new BufferedReader(new DotTerminatedMessageReader(_reader_)); while ((line = reader.readLine()) != null) list.addElement(line); size = list.size(); if (size < 1) return new String[0]; result = new String[size]; list.copyInto(result); return result; } /*** * 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. *

* For example *

     * 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;
     * 
*

* @return True if successfully completed, false if not. * @exception 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. * @exception 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 * isAllowedToPost() before trying to post. However, a posting * attempt can fail due to malformed headers. *

* 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. *

* Different NNTP servers will require different header formats, but * you can use the provided * 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. *

* Upon closing the returned Writer, you need to call * completePendingCommand() * to finalize the posting and verify its success or failure from * the server reply. *

* @return A DotTerminatedMessageWriter to which the article (including * header) can be written. Returns null if the command fails. * @exception 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(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. *

* @return True if successfully completed, false if not. * @exception 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. *

* @param username a valid username * @param password the corresponding password * @return True for successful login, false for a failure * @throws IOException */ public boolean authenticate(String username, String password) throws IOException { int replyCode = authinfoUser(username); if (replyCode == NNTPReply.MORE_AUTH_INFO_REQUIRED) { replyCode = authinfoPass(password); if (replyCode == NNTPReply.AUTHENTICATION_ACCEPTED) { _isAllowedToPost = true; return true; } } return false; } /*** * Private implementation of XOVER functionality. * * See * for legal agument formats. Alternatively, read RFC 2980 :-) *

* @param articleRange * @return Returns a DotTerminatedMessageReader if successful, null * otherwise * @exception IOException */ private Reader __retrieveArticleInfo(String articleRange) throws IOException { if (!NNTPReply.isPositiveCompletion(xover(articleRange))) return null; return new DotTerminatedMessageReader(_reader_); } /** * Return article headers for a specified post. *

* @param articleNumber the article to retrieve headers for * @return a DotTerminatedReader if successful, null otherwise * @throws IOException */ public Reader retrieveArticleInfo(int articleNumber) throws IOException { return __retrieveArticleInfo(Integer.toString(articleNumber)); } /** * Return article headers for all articles between lowArticleNumber * and highArticleNumber, inclusively. *

* @param lowArticleNumber * @param highArticleNumber * @return a DotTerminatedReader if successful, null otherwise * @throws IOException */ public Reader retrieveArticleInfo(int lowArticleNumber, int highArticleNumber) throws IOException { return __retrieveArticleInfo(new String(lowArticleNumber + "-" + highArticleNumber)); } /*** * Private implementation of XHDR functionality. * * See * for legal agument formats. Alternatively, read RFC 1036. *

* @param header * @param articleRange * @return Returns a DotTerminatedMessageReader if successful, null * otherwise * @exception IOException */ private Reader __retrieveHeader(String header, String articleRange) throws IOException { if (!NNTPReply.isPositiveCompletion(xhdr(header, articleRange))) return null; return new DotTerminatedMessageReader(_reader_); } /** * Return an article header for a specified post. *

* @param header the header to retrieve * @param articleNumber the article to retrieve the header for * @return a DotTerminatedReader if successful, null otherwise * @throws IOException */ public Reader retrieveHeader(String header, int articleNumber) throws IOException { return __retrieveHeader(header, Integer.toString(articleNumber)); } /** * Return an article header for all articles between lowArticleNumber * and highArticleNumber, inclusively. *

* @param header * @param lowArticleNumber * @param highArticleNumber * @return a DotTerminatedReader if successful, null otherwise * @throws IOException */ public Reader retrieveHeader(String header, int lowArticleNumber, int highArticleNumber) throws IOException { return __retrieveHeader(header, new String(lowArticleNumber + "-" + highArticleNumber)); } } /* Emacs configuration * Local variables: ** * mode: java ** * c-basic-offset: 4 ** * indent-tabs-mode: nil ** * End: ** */

... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2024 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.