offlinemessagestore.java

基于Jabber协议的即时消息服务器

                xmlReaders.add(xmlReader);
            }
            DbConnectionManager.closeConnection(pstmt, con);
        }
        return messages;
    }

    /**
     * Returns the offline message of the specified user with the given creation date. The
     * returned message will NOT be deleted from the database.
     *
     * @param username the username of the user who's message you'd like to receive.
     * @param creationDate the date when the offline message was stored in the database.
     * @return the offline message of the specified user with the given creation stamp.
     */
    public OfflineMessage getMessage(String username, Date creationDate) {
        OfflineMessage message = null;
        Connection con = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        SAXReader xmlReader = null;
        try {
            // Get a sax reader from the pool
            xmlReader = xmlReaders.take();
            con = DbConnectionManager.getConnection();
            pstmt = con.prepareStatement(LOAD_OFFLINE_MESSAGE);
            pstmt.setString(1, username);
            pstmt.setString(2, StringUtils.dateToMillis(creationDate));
            rs = pstmt.executeQuery();
            while (rs.next()) {
                String msgXML = rs.getString(1);
                message = new OfflineMessage(creationDate,
                        xmlReader.read(new StringReader(msgXML)).getRootElement());
                // Add a delayed delivery (JEP-0091) element to the message.
                Element delay = message.addChildElement("x", "jabber:x:delay");
                delay.addAttribute("from", XMPPServer.getInstance().getServerInfo().getName());
                delay.addAttribute("stamp", dateFormat.format(creationDate));
            }
        }
        catch (Exception e) {
            Log.error("Error retrieving offline messages of username: " + username +
                    " creationDate: " + creationDate, e);
        }
        finally {
            // Return the sax reader to the pool
            if (xmlReader != null) {
                xmlReaders.add(xmlReader);
            }
            DbConnectionManager.closeConnection(rs, pstmt, con);
        }
        return message;
    }

    /**
     * Deletes all offline messages in the store for a user.
     *
     * @param username the username of the user who's messages are going to be deleted.
     */
    public void deleteMessages(String username) {
        Connection con = null;
        PreparedStatement pstmt = null;
        try {
            con = DbConnectionManager.getConnection();
            pstmt = con.prepareStatement(DELETE_OFFLINE);
            pstmt.setString(1, username);
            pstmt.executeUpdate();
            
            removeUsernameFromSizeCache(username);
        }
        catch (Exception e) {
            Log.error("Error deleting offline messages of username: " + username, e);
        }
        finally {
            DbConnectionManager.closeConnection(pstmt, con);
        }
    }

    private void removeUsernameFromSizeCache(String username) {
        // Update the cached size if it exists.
        if (sizeCache.containsKey(username)) {
            sizeCache.remove(username);
        }
    }

    /**
     * Deletes the specified offline message in the store for a user. The way to identify the
     * message to delete is based on the creationDate and username.
     *
     * @param username the username of the user who's message is going to be deleted.
     * @param creationDate the date when the offline message was stored in the database.
     */
    public void deleteMessage(String username, Date creationDate) {
        Connection con = null;
        PreparedStatement pstmt = null;
        try {
            con = DbConnectionManager.getConnection();
            pstmt = con.prepareStatement(DELETE_OFFLINE_MESSAGE);
            pstmt.setString(1, username);
            pstmt.setString(2, StringUtils.dateToMillis(creationDate));
            pstmt.executeUpdate();
            
            // Force a refresh for next call to getSize(username),
            // it's easier than loading the message to be deleted just
            // to update the cache.
            removeUsernameFromSizeCache(username);
        }
        catch (Exception e) {
            Log.error("Error deleting offline messages of username: " + username +
                    " creationDate: " + creationDate, e);
        }
        finally {
            DbConnectionManager.closeConnection(pstmt, con);
        }
    }

    /**
     * Returns the approximate size (in bytes) of the XML messages stored for
     * a particular user.
     *
     * @param username the username of the user.
     * @return the approximate size of stored messages (in bytes).
     */
    public int getSize(String username) {
        // See if the size is cached.
        if (sizeCache.containsKey(username)) {
            return sizeCache.get(username);
        }
        int size = 0;
        Connection con = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        try {
            con = DbConnectionManager.getConnection();
            pstmt = con.prepareStatement(SELECT_SIZE_OFFLINE);
            pstmt.setString(1, username);
            rs = pstmt.executeQuery();
            if (rs.next()) {
                size = rs.getInt(1);
            }
            // Add the value to cache.
            sizeCache.put(username, size);
        }
        catch (Exception e) {
            Log.error(LocaleUtils.getLocalizedString("admin.error"), e);
        }
        finally {
            DbConnectionManager.closeConnection(rs, pstmt, con);
        }
        return size;
    }

    /**
     * Returns the approximate size (in bytes) of the XML messages stored for all
     * users.
     *
     * @return the approximate size of all stored messages (in bytes).
     */
    public int getSize() {
        int size = 0;
        Connection con = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;
        try {
            con = DbConnectionManager.getConnection();
            pstmt = con.prepareStatement(SELECT_SIZE_ALL_OFFLINE);
            rs = pstmt.executeQuery();
            if (rs.next()) {
                size = rs.getInt(1);
            }
        }
        catch (Exception e) {
            Log.error(LocaleUtils.getLocalizedString("admin.error"), e);
        }
        finally {
            DbConnectionManager.closeConnection(rs, pstmt, con);
        }
        return size;
    }

    public void userCreated(User user, Map params) {
        //Do nothing
    }

    public void userDeleting(User user, Map params) {
        // Delete all offline messages of the user
        deleteMessages(user.getUsername());
    }

    public void userModified(User user, Map params) {
        //Do nothing
    }

    public void start() throws IllegalStateException {
        super.start();
        // Initialize the pool of sax readers
        for (int i=0; i<10; i++) {
            SAXReader xmlReader = new SAXReader();
            xmlReader.setEncoding("UTF-8");
            xmlReaders.add(xmlReader);
        }
        // Add this module as a user event listener so we can delete
        // all offline messages when a user is deleted
        UserEventDispatcher.addListener(this);
    }

    public void stop() {
        super.stop();
        // Clean up the pool of sax readers
        xmlReaders.clear();
        // Remove this module as a user event listener
        UserEventDispatcher.removeListener(this);
    }
}