Class NNTP

Direct Known Subclasses:
NNTPClient

public class NNTP extends SocketClient
The NNTP class is not meant to be used by itself and is provided only so that you may easily implement your own NNTP client if you so desire. If you have no need to perform your own implementation, you should use NNTPClient. The NNTP class is made public to provide access to various NNTP constants and to make it easier for adventurous programmers (or those with special needs) to interact with the NNTP protocol and implement their own clients. A set of methods with names corresponding to the NNTP command names are provided to facilitate this interaction.

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
See Also:
  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    A ProtocolCommandSupport object used to manage the registering of ProtocolCommandListeners and te firing of ProtocolCommandEvents.
    static final int
    The default NNTP port.
  • Constructor Summary

    Constructors
    Constructor
    Description
    The default NNTP constructor.
  • Method Summary

    Modifier and Type
    Method
    Description
    protected void
    Initiates control connections and gets initial reply, determining if the client is allowed to post to the server.
    void
    Adds a ProtocolCommandListener.
    int
    A convenience method to send the NNTP ARTICLE command to the server, receive the initial reply, and return the reply code.
    int
    article(int articleNumber)
    A convenience method to send the NNTP ARTICLE command to the server, receive the initial reply, and return the reply code.
    int
    article(String messageId)
    A convenience method to send the NNTP ARTICLE command to the server, receive the initial reply, and return the reply code.
    int
    A convenience method to send the NNTP BODY command to the server, receive the initial reply, and return the reply code.
    int
    body(int articleNumber)
    A convenience method to send the NNTP BODY command to the server, receive the initial reply, and return the reply code.
    int
    body(String messageId)
    A convenience method to send the NNTP BODY command to the server, receive the initial reply, and return the reply code.
    void
    Closes the connection to the NNTP server and sets to null some internal data so that the memory may be reclaimed by the garbage collector.
    int
    Fetches a reply from the NNTP server and returns the integer reply code.
    int
    Returns the integer value of the reply code of the last NNTP reply.
    Returns the entire text of the last NNTP server response exactly as it was received, not including the end of line marker.
    int
    group(String newsgroup)
    A convenience method to send the NNTP GROUP command to the server, receive the reply, and return the reply code.
    int
    A convenience method to send the NNTP HEAD command to the server, receive the initial reply, and return the reply code.
    int
    head(int articleNumber)
    A convenience method to send the NNTP HEAD command to the server, receive the initial reply, and return the reply code.
    int
    head(String messageId)
    A convenience method to send the NNTP HEAD command to the server, receive the initial reply, and return the reply code.
    int
    A convenience method to send the NNTP HELP command to the server, receive the reply, and return the reply code.
    int
    ihave(String messageId)
    A convenience method to send the NNTP IHAVE command to the server, receive the reply, and return the reply code.
    boolean
    Indicates whether or not the client is allowed to post articles to the server it is currently connected to.
    int
    A convenience method to send the NNTP LAST command to the server, receive the reply, and return the reply code.
    int
    A convenience method to send the NNTP LIST command to the server, receive the reply, and return the reply code.
    int
    newgroups(String date, String time, boolean GMT, String distributions)
    A convenience method to send the NNTP NEWGROUPS command to the server, receive the reply, and return the reply code.
    int
    newnews(String newsgroups, String date, String time, boolean GMT, String distributions)
    A convenience method to send the NNTP NEWGROUPS command to the server, receive the reply, and return the reply code.
    int
    A convenience method to send the NNTP NEXT command to the server, receive the reply, and return the reply code.
    int
    A convenience method to send the NNTP POST command to the server, receive the reply, and return the reply code.
    int
    A convenience method to send the NNTP QUIT command to the server, receive the reply, and return the reply code.
    void
    Removes a ProtocolCommandListener.
    int
    sendCommand(int command)
    Sends an NNTP command with no arguments to the server, waits for a reply and returns the numerical response code.
    int
    sendCommand(int command, String args)
    Sends an NNTP command to the server, waits for a reply and returns the numerical response code.
    int
    Sends an NNTP command with no arguments to the server, waits for a reply and returns the numerical response code.
    int
    sendCommand(String command, String args)
    Sends an NNTP command to the server, waits for a reply and returns the numerical response code.
    int
    A convenience method to send the NNTP STAT command to the server, receive the initial reply, and return the reply code.
    int
    stat(int articleNumber)
    A convenience method to send the NNTP STAT command to the server, receive the initial reply, and return the reply code.
    int
    stat(String messageId)
    A convenience method to send the NNTP STAT command to the server, receive the initial reply, and return the reply code.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
  • Field Details

    • DEFAULT_PORT

      public static final int DEFAULT_PORT
      The default NNTP port. Its value is 119 according to RFC 977.
      See Also:
    • _commandSupport_

      protected ProtocolCommandSupport _commandSupport_
      A ProtocolCommandSupport object used to manage the registering of ProtocolCommandListeners and te firing of ProtocolCommandEvents.
  • Constructor Details

    • NNTP

      public NNTP()
      The default NNTP constructor. Sets the default port to DEFAULT_PORT and initializes internal data structures for saving NNTP reply information.
  • Method Details

    • _connectAction_

      protected void _connectAction_() throws IOException
      Initiates control connections and gets initial reply, determining if the client is allowed to post to the server.
      Overrides:
      _connectAction_ in class SocketClient
      Throws:
      IOException
    • addProtocolCommandListener

      public void addProtocolCommandListener(ProtocolCommandListener listener)
      Adds a ProtocolCommandListener. Delegates this task to _commandSupport_ .

      Parameters:
      listener - The ProtocolCommandListener to add.
    • removeProtocolCommandistener

      public void removeProtocolCommandistener(ProtocolCommandListener listener)
      Removes a ProtocolCommandListener. Delegates this task to _commandSupport_ .

      Parameters:
      listener - The ProtocolCommandListener to remove.
    • disconnect

      public void disconnect() throws IOException
      Closes the connection to the NNTP server and sets to null some internal data so that the memory may be reclaimed by the garbage collector. The reply text and code information from the last command is voided so that the memory it used may be reclaimed.

      Overrides:
      disconnect in class SocketClient
      Throws:
      IOException - If an error occurs while disconnecting.
    • isAllowedToPost

      public boolean isAllowedToPost()
      Indicates whether or not the client is allowed to post articles to the server it is currently connected to.

      Returns:
      True if the client can post articles to the server, false otherwise.
    • sendCommand

      public int sendCommand(String command, String args) throws IOException
      Sends an NNTP command to the server, waits for a reply and returns the numerical response code. After invocation, for more detailed information, the actual reply text can be accessed by calling getReplyString .

      Parameters:
      command - The text representation of the NNTP command to send.
      args - The arguments to the NNTP command. If this parameter is set to null, then the command is sent with no argument.
      Returns:
      The integer value of the NNTP reply code returned by the server in response to the command.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • sendCommand

      public int sendCommand(int command, String args) throws IOException
      Sends an NNTP command to the server, waits for a reply and returns the numerical response code. After invocation, for more detailed information, the actual reply text can be accessed by calling getReplyString .

      Parameters:
      command - The NNTPCommand constant corresponding to the NNTP command to send.
      args - The arguments to the NNTP command. If this parameter is set to null, then the command is sent with no argument.
      Returns:
      The integer value of the NNTP reply code returned by the server in response to the command. in response to the command.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • sendCommand

      public int sendCommand(String command) throws IOException
      Sends an NNTP command with no arguments to the server, waits for a reply and returns the numerical response code. After invocation, for more detailed information, the actual reply text can be accessed by calling getReplyString .

      Parameters:
      command - The text representation of the NNTP command to send.
      Returns:
      The integer value of the NNTP reply code returned by the server in response to the command. in response to the command.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • sendCommand

      public int sendCommand(int command) throws IOException
      Sends an NNTP command with no arguments to the server, waits for a reply and returns the numerical response code. After invocation, for more detailed information, the actual reply text can be accessed by calling getReplyString .

      Parameters:
      command - The NNTPCommand constant corresponding to the NNTP command to send.
      Returns:
      The integer value of the NNTP reply code returned by the server in response to the command. in response to the command.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • getReplyCode

      public int getReplyCode()
      Returns the integer value of the reply code of the last NNTP reply. You will usually only use this method after you connect to the NNTP server to check that the connection was successful since connect is of type void.

      Returns:
      The integer value of the reply code of the last NNTP reply.
    • getReply

      public int getReply() throws IOException
      Fetches a reply from the NNTP server and returns the integer reply code. After calling this method, the actual reply text can be accessed from getReplyString . Only use this method if you are implementing your own NNTP client or if you need to fetch a secondary response from the NNTP server.

      Returns:
      The integer value of the reply code of the fetched NNTP reply. in response to the command.
      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.
      IOException - If an I/O error occurs while receiving the server reply.
    • getReplyString

      public String getReplyString()
      Returns the entire text of the last NNTP server response exactly as it was received, not including the end of line marker.

      Returns:
      The entire text from the last NNTP response as a String.
    • article

      public int article(String messageId) throws IOException
      A convenience method to send the NNTP ARTICLE command to the server, receive the initial reply, and return the reply code.

      Parameters:
      messageId - The message identifier of the requested article, including the encapsulating invalid input: '&lt' and invalid input: '&gt' characters.
      Returns:
      The reply code received from the server.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • article

      public int article(int articleNumber) throws IOException
      A convenience method to send the NNTP ARTICLE command to the server, receive the initial reply, and return the reply code.

      Parameters:
      articleNumber - The number of the article to request from the currently selected newsgroup.
      Returns:
      The reply code received from the server.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • article

      public int article() throws IOException
      A convenience method to send the NNTP ARTICLE command to the server, receive the initial reply, and return the reply code.

      Returns:
      The reply code received from the server.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • body

      public int body(String messageId) throws IOException
      A convenience method to send the NNTP BODY command to the server, receive the initial reply, and return the reply code.

      Parameters:
      messageId - The message identifier of the requested article, including the encapsulating invalid input: '&lt' and invalid input: '&gt' characters.
      Returns:
      The reply code received from the server.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • body

      public int body(int articleNumber) throws IOException
      A convenience method to send the NNTP BODY command to the server, receive the initial reply, and return the reply code.

      Parameters:
      articleNumber - The number of the article to request from the currently selected newsgroup.
      Returns:
      The reply code received from the server.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • body

      public int body() throws IOException
      A convenience method to send the NNTP BODY command to the server, receive the initial reply, and return the reply code.

      Returns:
      The reply code received from the server.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • head

      public int head(String messageId) throws IOException
      A convenience method to send the NNTP HEAD command to the server, receive the initial reply, and return the reply code.

      Parameters:
      messageId - The message identifier of the requested article, including the encapsulating invalid input: '&lt' and invalid input: '&gt' characters.
      Returns:
      The reply code received from the server.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • head

      public int head(int articleNumber) throws IOException
      A convenience method to send the NNTP HEAD command to the server, receive the initial reply, and return the reply code.

      Parameters:
      articleNumber - The number of the article to request from the currently selected newsgroup.
      Returns:
      The reply code received from the server.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • head

      public int head() throws IOException
      A convenience method to send the NNTP HEAD command to the server, receive the initial reply, and return the reply code.

      Returns:
      The reply code received from the server.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • stat

      public int stat(String messageId) throws IOException
      A convenience method to send the NNTP STAT command to the server, receive the initial reply, and return the reply code.

      Parameters:
      messageId - The message identifier of the requested article, including the encapsulating invalid input: '&lt' and invalid input: '&gt' characters.
      Returns:
      The reply code received from the server.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • stat

      public int stat(int articleNumber) throws IOException
      A convenience method to send the NNTP STAT command to the server, receive the initial reply, and return the reply code.

      Parameters:
      articleNumber - The number of the article to request from the currently selected newsgroup.
      Returns:
      The reply code received from the server.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • stat

      public int stat() throws IOException
      A convenience method to send the NNTP STAT command to the server, receive the initial reply, and return the reply code.

      Returns:
      The reply code received from the server.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • group

      public int group(String newsgroup) throws IOException
      A convenience method to send the NNTP GROUP command to the server, receive the reply, and return the reply code.

      Parameters:
      newsgroup - The name of the newsgroup to select.
      Returns:
      The reply code received from the server.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • help

      public int help() throws IOException
      A convenience method to send the NNTP HELP command to the server, receive the reply, and return the reply code.

      Returns:
      The reply code received from the server.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • ihave

      public int ihave(String messageId) throws IOException
      A convenience method to send the NNTP IHAVE command to the server, receive the reply, and return the reply code.

      Parameters:
      messageId - The article identifier, including the encapsulating invalid input: '&lt' and invalid input: '&gt' characters.
      Returns:
      The reply code received from the server.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • last

      public int last() throws IOException
      A convenience method to send the NNTP LAST command to the server, receive the reply, and return the reply code.

      Returns:
      The reply code received from the server.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • list

      public int list() throws IOException
      A convenience method to send the NNTP LIST command to the server, receive the reply, and return the reply code.

      Returns:
      The reply code received from the server.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • next

      public int next() throws IOException
      A convenience method to send the NNTP NEXT command to the server, receive the reply, and return the reply code.

      Returns:
      The reply code received from the server.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • newgroups

      public int newgroups(String date, String time, boolean GMT, String distributions) throws IOException
      A convenience method to send the NNTP NEWGROUPS command to the server, receive the reply, and return the reply code.

      Parameters:
      date - The date after which to check for new groups. Date format is YYMMDD
      time - The time after which to check for new groups. Time format is HHMMSS using a 24-hour clock.
      GMT - True if the time is in GMT, false if local server time.
      distributions - Comma-separated distribution list to check for new groups. Set to null if no distributions.
      Returns:
      The reply code received from the server.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • newnews

      public int newnews(String newsgroups, String date, String time, boolean GMT, String distributions) throws IOException
      A convenience method to send the NNTP NEWGROUPS command to the server, receive the reply, and return the reply code.

      Parameters:
      newsgroups - A comma-separated list of newsgroups to check for new news.
      date - The date after which to check for new news. Date format is YYMMDD
      time - The time after which to check for new news. Time format is HHMMSS using a 24-hour clock.
      GMT - True if the time is in GMT, false if local server time.
      distributions - Comma-separated distribution list to check for new news. Set to null if no distributions.
      Returns:
      The reply code received from the server.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • post

      public int post() throws IOException
      A convenience method to send the NNTP POST command to the server, receive the reply, and return the reply code.

      Returns:
      The reply code received from the server.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.
    • quit

      public int quit() throws IOException
      A convenience method to send the NNTP QUIT command to the server, receive the reply, and return the reply code.

      Returns:
      The reply code received from the server.
      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.
      IOException - If an I/O error occurs while either sending the command or receiving the server reply.