pop3client.java

来自「apache推出的net包」· Java 代码 · 共 550 行 · 第 1/2 页

    /***
     * Reset the POP3 session.  This is useful for undoing any message
     * deletions that may have been performed.  A reset attempt can only
     * succeed if the client is in the
     * {@link org.apache.commons.net.pop3.POP3#TRANSACTION_STATE TRANSACTION_STATE }
     * .
     * <p>
     * @return True if the reset attempt was successful, false if not.
     * @exception IOException If a network I/O error occurs in the process of
     *      sending the reset command.
     ***/
    public boolean reset() throws IOException
    {
        if (getState() == TRANSACTION_STATE)
            return (sendCommand(POP3Command.RSET) == POP3Reply.OK);
        return false;
    }

    /***
     * Get the mailbox status.  A status attempt can only
     * succeed if the client is in the
     * {@link org.apache.commons.net.pop3.POP3#TRANSACTION_STATE TRANSACTION_STATE }
     * .  Returns a POP3MessageInfo instance
     * containing the number of messages in the mailbox and the total
     * size of the messages in bytes.  Returns null if the status the
     * attempt fails.
     * <p>
     * @return A POP3MessageInfo instance containing the number of
     *         messages in the mailbox and the total size of the messages
     *         in bytes.  Returns null if the status the attempt fails.
     * @exception IOException If a network I/O error occurs in the process of
     *       sending the status command.
     ***/
    public POP3MessageInfo status() throws IOException
    {
        if (getState() != TRANSACTION_STATE)
            return null;
        if (sendCommand(POP3Command.STAT) != POP3Reply.OK)
            return null;
        return __parseStatus(_lastReplyLine.substring(3));
    }


    /***
     * List an individual message.  A list attempt can only
     * succeed if the client is in the
     * {@link org.apache.commons.net.pop3.POP3#TRANSACTION_STATE TRANSACTION_STATE }
     * .  Returns a POP3MessageInfo instance
     * containing the number of the listed message and the
     * size of the message in bytes.  Returns null if the list
     * attempt fails (e.g., if the specified message number does
     * not exist).
     * <p>
     * @param messageId  The number of the message list.
     * @return A POP3MessageInfo instance containing the number of the
     *         listed message and the size of the message in bytes.  Returns
     *         null if the list attempt fails.
     * @exception IOException If a network I/O error occurs in the process of
     *         sending the list command.
     ***/
    public POP3MessageInfo listMessage(int messageId) throws IOException
    {
        if (getState() != TRANSACTION_STATE)
            return null;
        if (sendCommand(POP3Command.LIST, Integer.toString(messageId))
                != POP3Reply.OK)
            return null;
        return __parseStatus(_lastReplyLine.substring(3));
    }


    /***
     * List all messages.  A list attempt can only
     * succeed if the client is in the
     * {@link org.apache.commons.net.pop3.POP3#TRANSACTION_STATE TRANSACTION_STATE }
     * .  Returns an array of POP3MessageInfo instances,
     * each containing the number of a message and its size in bytes.
     * If there are no messages, this method returns a zero length array.
     * If the list attempt fails, it returns null.
     * <p>
     * @return An array of POP3MessageInfo instances representing all messages
     * in the order they appear in the mailbox,
     * each containing the number of a message and its size in bytes.
     * If there are no messages, this method returns a zero length array.
     * If the list attempt fails, it returns null.
     * @exception IOException If a network I/O error occurs in the process of
     *     sending the list command.
     ***/
    public POP3MessageInfo[] listMessages() throws IOException
    {
        POP3MessageInfo[] messages;
        Enumeration en;
        int line;

        if (getState() != TRANSACTION_STATE)
            return null;
        if (sendCommand(POP3Command.LIST) != POP3Reply.OK)
            return null;
        getAdditionalReply();

        // This could be a zero length array if no messages present
        messages = new POP3MessageInfo[_replyLines.size() - 2];
        en = _replyLines.elements();

        // Skip first line
        en.nextElement();

        // Fetch lines.
        for (line = 0; line < messages.length; line++)
            messages[line] = __parseStatus((String)en.nextElement());

        return messages;
    }

    /***
     * List the unique identifier for a message.  A list attempt can only
     * succeed if the client is in the
     * {@link org.apache.commons.net.pop3.POP3#TRANSACTION_STATE TRANSACTION_STATE }
     * .  Returns a POP3MessageInfo instance
     * containing the number of the listed message and the
     * unique identifier for that message.  Returns null if the list
     * attempt fails  (e.g., if the specified message number does
     * not exist).
     * <p>
     * @param messageId  The number of the message list.
     * @return A POP3MessageInfo instance containing the number of the
     *         listed message and the unique identifier for that message.
     *         Returns null if the list attempt fails.
     * @exception IOException If a network I/O error occurs in the process of
     *        sending the list unique identifier command.
     ***/
    public POP3MessageInfo listUniqueIdentifier(int messageId)
    throws IOException
    {
        if (getState() != TRANSACTION_STATE)
            return null;
        if (sendCommand(POP3Command.UIDL, Integer.toString(messageId))
                != POP3Reply.OK)
            return null;
        return __parseUID(_lastReplyLine.substring(3));
    }


    /***
     * List the unique identifiers for all messages.  A list attempt can only
     * succeed if the client is in the
     * {@link org.apache.commons.net.pop3.POP3#TRANSACTION_STATE TRANSACTION_STATE }
     * .  Returns an array of POP3MessageInfo instances,
     * each containing the number of a message and its unique identifier.
     * If there are no messages, this method returns a zero length array.
     * If the list attempt fails, it returns null.
     * <p>
     * @return An array of POP3MessageInfo instances representing all messages
     * in the order they appear in the mailbox,
     * each containing the number of a message and its unique identifier
     * If there are no messages, this method returns a zero length array.
     * If the list attempt fails, it returns null.
     * @exception IOException If a network I/O error occurs in the process of
     *     sending the list unique identifier command.
     ***/
    public POP3MessageInfo[] listUniqueIdentifiers() throws IOException
    {
        POP3MessageInfo[] messages;
        Enumeration en;
        int line;

        if (getState() != TRANSACTION_STATE)
            return null;
        if (sendCommand(POP3Command.UIDL) != POP3Reply.OK)
            return null;
        getAdditionalReply();

        // This could be a zero length array if no messages present
        messages = new POP3MessageInfo[_replyLines.size() - 2];
        en = _replyLines.elements();

        // Skip first line
        en.nextElement();

        // Fetch lines.
        for (line = 0; line < messages.length; line++)
            messages[line] = __parseUID((String)en.nextElement());

        return messages;
    }


    /***
     * Retrieve a message from the POP3 server.  A retrieve message attempt
     * can only succeed if the client is in the
     * {@link org.apache.commons.net.pop3.POP3#TRANSACTION_STATE TRANSACTION_STATE }
     * .  Returns a DotTerminatedMessageReader instance
     * from which the entire message can be read.
     * Returns null if the retrieval attempt fails  (e.g., if the specified
     * message number does not exist).
     * <p>
     * You must not issue any commands to the POP3 server (i.e., call any
     * other methods) until you finish reading the message from the
     * returned Reader instance.
     * The POP3 protocol uses the same stream for issuing commands as it does
     * for returning results.  Therefore the returned Reader actually reads
     * directly from the POP3 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 messageId  The number of the message to fetch.
     * @return A DotTerminatedMessageReader instance
     * from which the entire message can be read.
     * Returns null if the retrieval attempt fails  (e.g., if the specified
     * message number does not exist).
     * @exception IOException If a network I/O error occurs in the process of
     *        sending the retrieve message command.
     ***/
    public Reader retrieveMessage(int messageId) throws IOException
    {
        if (getState() != TRANSACTION_STATE)
            return null;
        if (sendCommand(POP3Command.RETR, Integer.toString(messageId))
                != POP3Reply.OK)
            return null;

        return new DotTerminatedMessageReader(_reader);
    }


    /***
     * Retrieve only the specified top number of lines of a message from the
     * POP3 server.  A retrieve top lines attempt
     * can only succeed if the client is in the
     * {@link org.apache.commons.net.pop3.POP3#TRANSACTION_STATE TRANSACTION_STATE }
     * .  Returns a DotTerminatedMessageReader instance
     * from which the specified top number of lines of the message can be
     * read.
     * Returns null if the retrieval attempt fails  (e.g., if the specified
     * message number does not exist).
     * <p>
     * You must not issue any commands to the POP3 server (i.e., call any
     * other methods) until you finish reading the message from the returned
     * Reader instance.
     * The POP3 protocol uses the same stream for issuing commands as it does
     * for returning results.  Therefore the returned Reader actually reads
     * directly from the POP3 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 messageId  The number of the message to fetch.
     * @param numLines  The top number of lines to fetch. This must be >= 0.
     * @return  A DotTerminatedMessageReader instance
     * from which the specified top number of lines of the message can be
     * read.
     * Returns null if the retrieval attempt fails  (e.g., if the specified
     * message number does not exist).
     * @exception IOException If a network I/O error occurs in the process of
     *       sending the top command.
     ***/
    public Reader retrieveMessageTop(int messageId, int numLines)
    throws IOException
    {
        if (numLines < 0 || getState() != TRANSACTION_STATE)
            return null;
        if (sendCommand(POP3Command.TOP, Integer.toString(messageId) + " " +
                        Integer.toString(numLines)) != POP3Reply.OK)
            return null;

        return new DotTerminatedMessageReader(_reader);
    }


}