package com.oreilly.forum.domain;

import java.util.Iterator;

/**
 * Information about a message board.
 */
public interface BoardSummary {
    /**
     * @return a unique ID for this board.
     */
    long getID( );

    /**
     * @return a name for this board.
     */
    String getName( );

    /**
     * @return a description for this board.
     */
    String getDescription( );

    /**
     * @return an iterator of <code>MonthYear</code> objects.
     */
    Iterator getMonthsWithMessages( );
} 

package com.oreilly.forum.domain;

/**
 * Represent a message, including the text.
 */
public interface Message extends MessageSummary {
    /**
     * @return the text of this message.
     */
    String getText( );
} 

package com.oreilly.forum.domain;

import java.util.*;

/**
 * Arranges a collection of MessageSummary objects into a tree.
 */
public class MessageTree {
    private List topLevelMsgs = new ArrayList( );

    // map ids to MessageSummary objects
    private Map idToMsgMap = new HashMap( );

    // map reply-to ids to lists of MessageSummary objects
    private Map replyIDToMsgListMap = new HashMap( );

    /**
     * Construct a new message tree from an iterator of MessageSummary
     * objects.
     */
    public MessageTree(Iterator messages) {
        while (messages.hasNext( )) {
            // store each message in a map for fast retrieval by ID
            MessageSummary curMsg = (MessageSummary) messages.next( );
            this.idToMsgMap.put(new Long(curMsg.getID( )), curMsg);

            // build the inverted map that maps reply-to IDs to
            // lists of messages
            Long curReplyID = new Long(curMsg.getInReplyTo( ));
            List replyToList =
                    (List) this.replyIDToMsgListMap.get(curReplyID);
            if (replyToList == null) {
                replyToList = new ArrayList( );
                this.replyIDToMsgListMap.put(curReplyID, replyToList);
            }
            replyToList.add(curMsg);
        }

        // build the list of top-level messages. A top-level message
        // fits one of the following two criteria:
        //  - its reply-to ID is -1
        //  - its reply-to ID was not found in the list of messages. This
        //    occurs when a message is a reply to a previous month's message
        Iterator iter = this.replyIDToMsgListMap.keySet().iterator( );
        while (iter.hasNext( )) {
            Long curReplyToID = (Long) iter.next( );
            if (curReplyToID.longValue( ) == -1
                    || !this.idToMsgMap.containsKey(curReplyToID)) {
                List msgsToAdd =
                        (List) this.replyIDToMsgListMap.get(curReplyToID);
                this.topLevelMsgs.addAll(msgsToAdd);
            }
        }
        Collections.sort(this.topLevelMsgs);
    }

    public Iterator getTopLevelMessages( ) {
        return this.topLevelMsgs.iterator( );
    }

    /**
     * @return an iterator of MessageSummary objects that are replies
     *         to the specified message.
     */
    public Iterator getReplies(MessageSummary msg) {
        List replies = (List) this.replyIDToMsgListMap.get(
                new Long(msg.getID( )));
        if (replies != null) {
            Collections.sort(replies);
            return replies.iterator( );
        } else {
            return Collections.EMPTY_LIST.iterator( );
        }
    }
} 

package com.oreilly.forum;

/**
 * Define application-wide configuration information. The Servlet
 * must call the setValues( ) method before any of the get
 * methods in this class can be used.
 */
public class ForumConfig {
    // maximum sizes of various fields in the database
    public static final int MAX_BOARD_NAME_LEN = 80;
    public static final int MAX_BOARD_DESC_LEN = 255;
    public static final int MAX_MSG_SUBJECT_LEN = 80;
    public static final int MAX_EMAIL_LEN = 80;

    private static String jdbcDriverClassName;
    private static String databaseURL;
    private static String adapterClassName;

    public static void setValues(
            String jdbcDriverClassName,
            String databaseURL,
            String adapterClassName) {
        ForumConfig.jdbcDriverClassName = jdbcDriverClassName;
        ForumConfig.databaseURL = databaseURL;
        ForumConfig.adapterClassName = adapterClassName;
    }

    /**
     * @return the JDBC driver class name.
     */
    public static String getJDBCDriverClassName( ) {
        return ForumConfig.jdbcDriverClassName;
    }

    /**
     * @return the JDBC database URL.
     */
    public static String getDatabaseURL( ) {
        return ForumConfig.databaseURL;
    }

    /**
     * @return the data adapter implementation class name.
     */
    public static String getAdapterClassName( ) {
        return ForumConfig.adapterClassName;
    }

    private ForumConfig( ) {
    }
}

package com.oreilly.forum.adapter;

import com.oreilly.forum.*;
import com.oreilly.forum.domain.*;
import java.util.*;

/**
 * Defines an interface to a data source.
 */
public abstract class DataAdapter {
    private static DataAdapter instance;

    /**
     * @return the singleton instance of this class.
     */
    public static synchronized DataAdapter getInstance( )
            throws DataException {
        if (instance == null) {
            String adapterClassName = ForumConfig.getAdapterClassName( );
            try {
                Class adapterClass = Class.forName(adapterClassName);
                instance = (DataAdapter) adapterClass.newInstance( );
            } catch (Exception ex) {
                throw new DataException("Unable to instantiate "
                        + adapterClassName);
            }
        }
        return instance;
    }

    /**
     * @param msgID must be a valid message identifier.
     * @return the message with the specified id.
     * @throws DataException if msgID does not exist or a database
     * error occurs.
     */
    public abstract Message getMessage(long msgID) throws DataException;

    /**
     * Add a reply to an existing message.
     *
     * @throws DataException if a database error occurs, or if any
     * parameter is illegal.
     */
    public abstract Message replyToMessage(long origMsgID, String msgSubject,
            String authorEmail, String msgText) throws DataException;

    /**
     * Post a new message.
     *
     * @return the newly created message.
     * @throws DataException if a database error occurs, or if any
     * parameter is illegal.
     */
    public abstract Message postNewMessage(long boardID, String msgSubject,
            String authorEmail, String msgText) throws DataException;

    /**
     * If no messages exist for the specified board and month, return
     * an empty iterator.
     * @return an iterator of <code>MessageSummary</code> objects.
     * @throws DataException if the boardID is illegal or a database
     * error occurs.
     */
    public abstract Iterator getAllMessages(long boardID, MonthYear month)
            throws DataException;

    /**
     * @return an iterator of all <code>BoardSummary</code> objects.
     */
    public abstract Iterator getAllBoards( ) throws DataException;

    /**
     * @return a board summary for the given id.
     * @throws DataException if boardID is illegal or a database
     *                       error occurs.
     */
    public abstract BoardSummary getBoardSummary(long boardID)
            throws DataException;
} 

# MySQL dump 8.8
#
# Host: localhost    Database: forum
#--------------------------------------------------------
# Server version	3.23.23-beta

#
# Table structure for table 'board'
#

CREATE TABLE board (
  id bigint(20) DEFAULT '0' NOT NULL,
  name char(80) DEFAULT '' NOT NULL,
  description char(255) DEFAULT '' NOT NULL,
  PRIMARY KEY (id)
);

#
# Dumping data for table 'board'
#

INSERT INTO board VALUES (0,'XSLT Basics',
    'How to create and use XSLT stylesheets and processors');
INSERT INTO board VALUES (1,'JAXP Programming Techniques','How to use JAXP 1.1');

#
# Table structure for table 'message'
#

CREATE TABLE message (
  id bigint(20) DEFAULT '0' NOT NULL,
  inReplyToID bigint(20) DEFAULT '0' NOT NULL,
  createMonth int(11) DEFAULT '0' NOT NULL,
  createDay int(11) DEFAULT '0' NOT NULL,
  createYear int(11) DEFAULT '0' NOT NULL,
  boardID bigint(20) DEFAULT '0' NOT NULL,
  subject varchar(80) DEFAULT '' NOT NULL,
  authorEmail varchar(80) DEFAULT '' NOT NULL,
  msgText text DEFAULT '' NOT NULL,
  PRIMARY KEY (id),
  KEY inReplyToID (inReplyToID),
  KEY createMonth (createMonth),
  KEY createDay (createDay),
  KEY boardID (boardID)
);

package com.oreilly.forum.jdbcimpl;

import java.io.*;
import java.sql.*;
import java.util.*;

/**
 * Helper methods for relational database access using JDBC.
 */
public class DBUtil {

    // a map of table names to maximum ID numbers
    private static Map tableToMaxIDMap = new HashMap( );

    /**
     * Close a statement and connection.
     */
    public static void close(Statement stmt, Connection con) {
        if (stmt != null) {
            try {
                stmt.close( );
            } catch (Exception ignored1) {
            }
        }
        if (con != null) {
            try {
                con.close( );
            } catch (Exception ignored2) {
            }
        }
    }

    /**
     * @return a new Connection to the database.
     */
    public static Connection getConnection(String dbURL)
            throws SQLException {
        // NOTE: implementing a connection pool would be a worthy
        //       enhancement
        return DriverManager.getConnection(dbURL);
    }

    /**
     * Close any connections that are still open. The Servlet will
     * call this method from its destroy( ) method.
     */
    public static void closeAllConnections( ) {
        // NOTE: if connection pooling is ever implemented, close
        //       the connections here.
    }

    /**
     * Store a long text field in the database. For example, a message's
     * text will be quite long and cannot be stored using JDBC's
     * setString( ) method.
     */
    public static void setLongString(PreparedStatement stmt,
            int columnIndex, String data) throws SQLException {
        if (data.length( ) > 0) {
            stmt.setAsciiStream(columnIndex,
                    new ByteArrayInputStream(data.getBytes( )),
                    data.length( ));
        } else {
            // this 'else' condition was introduced as a bug fix.  It was
            // discovered that the 'setAsciiStream' code shown above
            // caused MS Access throws a "function sequence error"
            // when the string was zero length.  This code now works.
            stmt.setString(columnIndex, "");
        }
    }

    /**
     * @return a long text field from the database.
     */
    public static String getLongString(ResultSet rs, int columnIndex)
            throws SQLException {
        try {
            InputStream in = rs.getAsciiStream(columnIndex);
            if (in == null) {
                return "";
            }

            byte[] arr = new byte[250];
            StringBuffer buf = new StringBuffer( );
            int numRead = in.read(arr);
            while (numRead != -1) {
                buf.append(new String(arr, 0, numRead));
                numRead = in.read(arr);
            }
            return buf.toString( );
        } catch (IOException ioe) {
            ioe.printStackTrace( );
            throw new SQLException(ioe.getMessage( ));
        }
    }

    /**
     * Compute a new unique ID. It is assumed that the specified table
     * has a column named 'id' of type 'long'. It is assumed that
     * that all parts of the program will use this method to compute
     * new IDs.
     * @return the next available unique ID for a table.
     */
    public static synchronized long getNextID(String tableName,
            Connection con) throws SQLException {
        Statement stmt = null;

        try {
            // if a max has already been retrieved from this table,
            // compute the next id without hitting the database
            if (tableToMaxIDMap.containsKey(tableName)) {
                Long curMax = (Long) tableToMaxIDMap.get(tableName);
                Long newMax = new Long(curMax.longValue( ) + 1L);
                tableToMaxIDMap.put(tableName, newMax);
                return newMax.longValue( );
            }

            stmt = con.createStatement( );
            ResultSet rs = stmt.executeQuery(
                    "SELECT MAX(id) FROM " + tableName);
            long max = 0;
            if (rs.next( )) {
                max = rs.getLong(1);
            }
            max++;
            tableToMaxIDMap.put(tableName, new Long(max));
            return max;
        } finally {
            // just close the statement
            close(stmt, null);
        }
    }
} 

package com.oreilly.forum.jdbcimpl;

import com.oreilly.forum.*;
import com.oreilly.forum.adapter.*;
import com.oreilly.forum.domain.*;
import java.sql.*;
import java.util.*;

/**
 * An implementation of the DataAdapter that uses JDBC.
 */
public class JdbcDataAdapter extends DataAdapter {

    private static String dbURL = ForumConfig.getDatabaseURL( );

    /**
     * Construct the data adapter and load the JDBC driver.
     */
    public JdbcDataAdapter( ) throws DataException {
        try {
            Class.forName(ForumConfig.getJDBCDriverClassName( ));
        } catch (Exception ex) {
            ex.printStackTrace( );
            throw new DataException("Unable to load JDBC driver: "
                    + ForumConfig.getJDBCDriverClassName( ));
        }
    }

    /**
     * @param msgID must be a valid message identifier.
     * @return the message with the specified id.
     * @throws DataException if msgID does not exist or a database
     * error occurs.
     */
    public Message getMessage(long msgID) throws DataException {
        Connection con = null;
        Statement stmt = null;
        try {
            con = DBUtil.getConnection(dbURL);
            stmt = con.createStatement( );
            ResultSet rs = stmt.executeQuery(
                    "SELECT inReplyToID, createDay, createMonth, createYear, "
                    + "boardID, subject, authorEmail, msgText "
                    + "FROM Message WHERE id="
                    + msgID);
            if (rs.next( )) {
                long inReplyToID = rs.getLong(1);
                int createDay = rs.getInt(2);
                int createMonth = rs.getInt(3);
                int createYear = rs.getInt(4);
                long boardID = rs.getLong(5);
                String subject = rs.getString(6);
                String authorEmail = rs.getString(7);
                String msgText = DBUtil.getLongString(rs, 8);

                BoardSummary boardSummary = this.getBoardSummary(boardID, stmt);

                return new MessageImpl(msgID,
                        new DayMonthYear(createDay, createMonth, createYear),
                        boardSummary, subject, authorEmail, msgText, 
                        inReplyToID);
            } else {
                throw new DataException("Illegal msgID");
            }
        } catch (SQLException sqe) {
            sqe.printStackTrace( );
            throw new DataException(sqe.getMessage( ));
        } finally {
            DBUtil.close(stmt, con);
        }
    }

    /**
     * Add a reply to an existing message.
     *
     * @throws DataException if a database error occurs, or if any
     * parameter is illegal.
     */
    public Message replyToMessage(long origMsgID,
            String msgSubject, String authorEmail, String msgText)
            throws DataException {
        Message inReplyToMsg = this.getMessage(origMsgID);
        return insertMessage(inReplyToMsg.getBoard( ), origMsgID,
                msgSubject, authorEmail, msgText);

    }

    /**
     * Post a new message.
     *
     * @return the newly created message.
     * @throws DataException if a database error occurs, or if any
     * parameter is illegal.
     */
    public Message postNewMessage(long boardID, String msgSubject,
            String authorEmail, String msgText) throws DataException {

        BoardSummary board = this.getBoardSummary(boardID);
        return insertMessage(board, -1, msgSubject, authorEmail, msgText);
    }

    /**
     * If no messages exist for the specified board and month, return
     * an empty iterator.
     * @return an iterator of <code>MessageSummary</code> objects.
     * @throws DataException if the boardID is illegal or a database
     * error occurs.
     */
    public Iterator getAllMessages(long boardID, MonthYear month)
            throws DataException {
        List allMsgs = new ArrayList( );

        Connection con = null;
        Statement stmt = null;
        try {
            con = DBUtil.getConnection(dbURL);
            stmt = con.createStatement( );

            BoardSummary boardSum = this.getBoardSummary(boardID, stmt);

            ResultSet rs = stmt.executeQuery(
                    "SELECT id, inReplyToID, createDay, "
                    + "subject, authorEmail "
                    + "FROM Message WHERE createMonth="
                    + month.getMonth( )
                    + " AND createYear="
                    + month.getYear( )
                    + " AND boardID="
                    + boardID);

            while (rs.next( )) {
                long msgID = rs.getLong(1);
                long inReplyTo = rs.getLong(2);
                int createDay = rs.getInt(3);
                String subject = rs.getString(4);
                String authorEmail = rs.getString(5);

                DayMonthYear createDMY = new DayMonthYear(
                        createDay, month.getMonth(), month.getYear( ));

                allMsgs.add(new MessageSummaryImpl(msgID, createDMY,
                        boardSum,
                        subject, authorEmail, inReplyTo));
            }
            return allMsgs.iterator( );
        } catch (SQLException sqe) {
            sqe.printStackTrace( );
            throw new DataException(sqe);
        } finally {
            DBUtil.close(stmt, con);
        }
    }

    /**
     * @return an iterator of all <code>BoardSummary</code> objects.
     */
    public Iterator getAllBoards( ) throws DataException {
        List allBoards = new ArrayList( );

        Connection con = null;
        Statement stmt = null;
        Statement stmt2 = null;
        try {
            con = DBUtil.getConnection(dbURL);
            stmt = con.createStatement( );
            stmt2 = con.createStatement( );
            ResultSet rs = stmt.executeQuery(
                    "SELECT id, name, description FROM Board "
                    + "ORDER BY name");

            while (rs.next( )) {
                long id = rs.getLong(1);
                String name = rs.getString(2);
                String description = rs.getString(3);

                // get the months with messages. Use a different
                // Statement object because we are in the middle of
                // traversing a ResultSet that was created with the
                // first Statement.
                List monthsWithMessages =
                        this.getMonthsWithMessages(id, stmt2);

                allBoards.add(new BoardSummaryImpl(id, name, description,
                        monthsWithMessages));
            }
            return allBoards.iterator( );
        } catch (SQLException sqe) {
            sqe.printStackTrace( );
            throw new DataException(sqe);
        } finally {
            if (stmt2 != null) {
                try {
                    stmt2.close( );
                } catch (SQLException ignored) {
                }
            }
            DBUtil.close(stmt, con);
        }
    }

    /**
     * @return a board summary for the given id.
     * @throws DataException if boardID is illegal or a database
     *                       error occurs.
     */
    public BoardSummary getBoardSummary(long boardID)
            throws DataException {
        Connection con = null;
        Statement stmt = null;
        try {
            con = DBUtil.getConnection(dbURL);
            stmt = con.createStatement( );
            return getBoardSummary(boardID, stmt);
        } catch (SQLException sqe) {
            sqe.printStackTrace( );
            throw new DataException(sqe);
        } finally {
            DBUtil.close(stmt, con);
        }
    }

    private BoardSummary getBoardSummary(long boardID, Statement stmt)
            throws DataException, SQLException {
        ResultSet rs = stmt.executeQuery(
                "SELECT name, description FROM Board WHERE id=" + boardID);

        if (rs.next( )) {
            String name = rs.getString(1);
            String description = rs.getString(2);

            List monthsWithMessages = getMonthsWithMessages(boardID, stmt);

            return new BoardSummaryImpl(boardID, name, description,
                    monthsWithMessages);
        } else {
            throw new DataException("Unknown boardID");
        }
    }

    /**
     * @return a list of MonthYear objects
     */
    private List getMonthsWithMessages(long boardID, Statement stmt)
            throws SQLException {

        List monthsWithMessages = new ArrayList( );
        ResultSet rs = stmt.executeQuery(
                "SELECT DISTINCT createMonth, createYear "
                + "FROM Message "
                + "WHERE boardID=" + boardID);
        while (rs.next( )) {
            monthsWithMessages.add(new MonthYear(
                    rs.getInt(1), rs.getInt(2)));
        }
        return monthsWithMessages;
    }

    private Message insertMessage(BoardSummary board, long inReplyToID,
            String msgSubject, String authorEmail,
            String msgText) throws DataException {
        // avoid overflowing the max database column lengths
        if (msgSubject.length( ) > ForumConfig.MAX_MSG_SUBJECT_LEN) {
            msgSubject = msgSubject.substring(0,
                    ForumConfig.MAX_MSG_SUBJECT_LEN);
        }
        if (authorEmail.length( ) > ForumConfig.MAX_EMAIL_LEN) {
            authorEmail = authorEmail.substring(0,
                    ForumConfig.MAX_EMAIL_LEN);
        }

        DayMonthYear createDate = new DayMonthYear( );

        Connection con = null;
        PreparedStatement stmt = null;
        try {
            con = DBUtil.getConnection(dbURL);
            long newMsgID = DBUtil.getNextID("Message", con);
            stmt = con.prepareStatement("INSERT INTO Message "
                    + "(id, inReplyToID, createMonth, createDay, createYear, "
                    + "boardID, subject, authorEmail, msgText) "
                    + "VALUES (?,?,?,?,?,?,?,?,?)");
            stmt.setString(1, Long.toString(newMsgID));
            stmt.setString(2, Long.toString(inReplyToID));
            stmt.setInt(3, createDate.getMonth( ));
            stmt.setInt(4, createDate.getDay( ));
            stmt.setInt(5, createDate.getYear( ));
            stmt.setString(6, Long.toString(board.getID( )));
            stmt.setString(7, msgSubject);
            stmt.setString(8, authorEmail);
            DBUtil.setLongString(stmt, 9, msgText);

            stmt.executeUpdate( );

            return new MessageImpl(newMsgID, createDate,
                    board, msgSubject, authorEmail,
                    msgText, inReplyToID);

        } catch (SQLException sqe) {
            sqe.printStackTrace( );
            throw new DataException(sqe);
        } finally {
            DBUtil.close(stmt, con);
        }
    }
} 

package com.oreilly.forum.xml;

import com.oreilly.forum.domain.*;
import java.util.*;
import org.jdom.*;

/**
 * Produce JDOM data for the home page.
 */
public class HomeJDOM {

    /**
     * @param boards an iterator of <code>BoardSummary</code> objects.
     */
    public static Element produceElement(Iterator boards) {
        Element homeElem = new Element("home");
        while (boards.hasNext( )) {
            BoardSummary curBoard = (BoardSummary) boards.next( );
            homeElem.addContent(BoardSummaryJDOM.produceElement(curBoard));
        }

        return homeElem;
    }

    private HomeJDOM( ) {
    }
}

package com.oreilly.forum.xml;

import java.util.*;
import com.oreilly.forum.*;
import com.oreilly.forum.adapter.*;
import com.oreilly.forum.domain.*;
import org.jdom.*;

/**
 * Creates the JDOM for the month view of a board.
 */
public class ViewMonthJDOM {

    /**
     * @param board the message board to generate JDOM for.
     * @param month the month and year to view.
     */
    public static Element produceElement(BoardSummary board,
            MonthYear month) throws DataException {
        Element viewMonthElem = new Element("viewMonth");
        viewMonthElem.addAttribute("month",
                Integer.toString(month.getMonth( )));
        viewMonthElem.addAttribute("year",
                Integer.toString(month.getYear( )));

        // create the <board> element...
        Element boardElem = BoardSummaryJDOM.produceNameIDElement(board);
        viewMonthElem.addContent(boardElem);

        DataAdapter adapter = DataAdapter.getInstance( );

        MessageTree msgTree = new MessageTree(adapter.getAllMessages(
                board.getID( ), month));

        // get an iterator of MessageSummary objects
        Iterator msgs = msgTree.getTopLevelMessages( );

        while (msgs.hasNext( )) {
            MessageSummary curMsg = (MessageSummary) msgs.next( );
            Element elem = produceMessageElement(curMsg, msgTree);
            viewMonthElem.addContent(elem);
        }

        return viewMonthElem;
    }

    /**
     * Produce a fragment of XML for an individual message. This
     * is a recursive function.
     */
    private static Element produceMessageElement(MessageSummary msg,
            MessageTree msgTree) {
        Element msgElem = new Element("message");
        msgElem.addAttribute("id", Long.toString(msg.getID( )));
        msgElem.addAttribute("day",
                Integer.toString(msg.getCreateDate().getDay( )));

        msgElem.addContent(new Element("subject")
                .setText(msg.getSubject( )));
        msgElem.addContent(new Element("authorEmail")
                .setText(msg.getAuthorEmail( )));

        Iterator iter = msgTree.getReplies(msg);
        while (iter.hasNext( )) {
            MessageSummary curReply = (MessageSummary) iter.next( );

            // recursively build the XML for all replies
            msgElem.addContent(produceMessageElement(curReply, msgTree));
        }
        return msgElem;
    }

    private ViewMonthJDOM( ) {
    }
} 

package com.oreilly.forum.xml;

import com.oreilly.forum.domain.*;
import java.util.Date;
import org.jdom.*;
import org.jdom.output.*;

/**
 * Generate JDOM for the View Message page.
 */
public class ViewMessageJDOM {

    /**
     * @param message the message to view.
     * @param inResponseTo the message this one is in response to, or
     * perhaps null.
     */
    public static Element produceElement(Message message,
            MessageSummary inResponseTo) {
        Element messageElem = new Element("message");
        messageElem.addAttribute("id", Long.toString(message.getID( )));
        DayMonthYear d = message.getCreateDate( );
        messageElem.addAttribute("month",
                Integer.toString(d.getMonth( )));
        messageElem.addAttribute("day",
                Integer.toString(d.getDay( )));
        messageElem.addAttribute("year",
                Integer.toString(d.getYear( )));

        Element boardElem = BoardSummaryJDOM.produceNameIDElement(
                message.getBoard( ));
        messageElem.addContent(boardElem);


        if (inResponseTo != null) {
            Element inRespToElem = new Element("inResponseTo")
                    .addAttribute("id", Long.toString(inResponseTo.getID( )));
            inRespToElem.addContent(new Element("subject")
                    .setText(inResponseTo.getSubject( )));
            messageElem.addContent(inRespToElem);
        }

        messageElem.addContent(new Element("subject")
                .setText(message.getSubject( )));
        messageElem.addContent(new Element("authorEmail")
                .setText(message.getAuthorEmail( )));
        messageElem.addContent(new Element("text")
                .setText(message.getText( )));
        return messageElem;
    }

    private ViewMessageJDOM( ) {
    }
} 

package com.oreilly.forum.xml;

import com.oreilly.forum.domain.*;
import java.util.*;
import org.jdom.*;

/**
 * Produces JDOM for a BoardSummary object.
 */
public class BoardSummaryJDOM {
    public static Element produceNameIDElement(BoardSummary board) {
        // produce the following:
        // <board id="123">
        //   <name>the board name</name>
        //   <description>board description</description>
        // </board>
        Element boardElem = new Element("board");
        boardElem.addAttribute("id", Long.toString(board.getID( )));
        boardElem.addContent(new Element("name")
                .setText(board.getName( )));
        boardElem.addContent(new Element("description")
                .setText(board.getDescription( )));
        return boardElem;
    }

    public static Element produceElement(BoardSummary board) {
        Element boardElem = produceNameIDElement(board);

        // add the list of messages
        Iterator iter = board.getMonthsWithMessages( );
        while (iter.hasNext( )) {
            MonthYear curMonth = (MonthYear) iter.next( );
            Element elem = new Element("messages");
            elem.addAttribute("month", Integer.toString(curMonth.getMonth( )));
            elem.addAttribute("year", Integer.toString(curMonth.getYear( )));
            boardElem.addContent(elem);
        }

        return boardElem;
    }

    private BoardSummaryJDOM( ) {
    }
}