Appendix A. Discussion Forum Code

package com.oreilly.forum.domain;

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

/**
 * An implementation of the BoardSummary interface.
 */
public class BoardSummaryImpl implements BoardSummary {
    private long id;
    private String name;
    private String description;
    private List monthsWithMessages;

    /**
     * @param monthsWithMessages a list of MonthYear objects.
     */
    public BoardSummaryImpl(long id, String name, String description,
            List monthsWithMessages) {
        this.id = id;
        this.name = name;
        this.description = description;
        this.monthsWithMessages = monthsWithMessages;

    }

    public long getID( ) {
        return this.id;
    }

    public String getName( ) {
        return this.name;
    }

    public String getDescription( ) {
        return this.description;
    }

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

package com.oreilly.forum.adapter;

/**
 * An exception that indicates some operation with the back-end
 * data source failed.
 */
public class DataException extends Exception {
    private Throwable rootCause;

    /**
     * Wrap a DataException around another throwable.
     */
    public DataException(Throwable rootCause) {
        super(rootCause.getMessage( ));
        this.rootCause = rootCause;
    }

    /**
     * Construct an exception with the specified detail message.
     */
    public DataException(String message) {
        super(message);
    }

    /**
     * @return a reference to the root exception or null.
     */
    public Throwable getRootCause( ) {
        return this.rootCause;
    }
} 

package com.oreilly.forum.domain;

import java.util.*;

/**
 * Misc utility functions for dates. Methods are synchronized because
 * the same Calendar instance is shared.
 */
public final class DateUtil {

    private static Calendar cal = Calendar.getInstance( );

    /**
     * @return the day of the month for a given date.
     */
    public synchronized static int getDayOfMonth(Date date) {
        cal.setTime(date);
        return cal.get(Calendar.DAY_OF_MONTH);
    }

    /**
     * @return the month number for a given date.
     */
    public synchronized static int getMonth(Date date) {
        cal.setTime(date);
        return cal.get(Calendar.MONTH);
    }

    /**
     * @return the year number for the given date.
     */
    public synchronized static int getYear(Date date) {
        cal.setTime(date);
        return cal.get(Calendar.YEAR);
    }

    private DateUtil( ) {
    }
}

package com.oreilly.forum.domain;

import java.util.Date;

/**
 * Represents a day, month, and year.
 */
public class DayMonthYear extends MonthYear {
    private int day;

    public DayMonthYear( ) {
        this(new Date( ));
    }

    public DayMonthYear(Date date) {
        super(date);
        this.day = DateUtil.getDayOfMonth(date);
    }

    public DayMonthYear(int day, int month, int year) {
        super(month, year);
        this.day = day;
    }

    public int getDay( ) {
        return this.day;
    }

    public boolean equals(Object obj) {
        if (obj instanceof DayMonthYear) {
            DayMonthYear rhs = (DayMonthYear) obj;
            return super.equals(obj) && this.day == rhs.day;
        }
        return false;
    }

    public int hashCode( ) {
        return super.hashCode( ) ^ this.day;
    }

    public int compareTo(Object obj) {
        DayMonthYear rhs = (DayMonthYear) obj;
        int comparison = super.compareTo(obj);
        if (comparison == 0) {
            if (this.day < rhs.day) {
                return -1;
            } else if (this.day > rhs.day) {
                return 1;
            }
        }
        return comparison;
    }

    public String toString( ) {
        return getMonth() + "/" + getDay() + "/" + getYear( );
    }
}

package com.oreilly.forum.fakeimpl;

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

public class FakeDataAdapter extends DataAdapter {
    // a list of BoardSummary objects
    private List allBoards;
    private static long nextMessageID = 0;
    private Map messageMap = new HashMap( );

    public FakeDataAdapter( ) throws DataException {
        this.allBoards = new ArrayList( );

        BoardSummary bs0 = new BoardSummaryImpl(0L,
                "Java Programming",
                "General programming questions about Java.");
        BoardSummary bs1 = new BoardSummaryImpl(1L,
                "XSLT Stylesheet Techniques",
                "Writing effective XSLT stylesheets.");
        this.allBoards.add(bs0);
        this.allBoards.add(bs1);

        this.postNewMessage(0L, "First subject in Java Prog",
                "burke_e@yahoo.com", "Sample message text");

    }

    /**
     * @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 {
        Message msg = (Message) this.messageMap.get(new Long(msgID));
        if (msg != null) {
            return msg;
        }
        throw new DataException("Invalid msgID");
    }

    /**
     * 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 {
        // this is slow, but works fine for a fake implementation
        List msgs = new ArrayList( );
        Iterator iter = this.messageMap.values().iterator( );
        while (iter.hasNext( )) {
            MessageSummary curMsg = (MessageSummary) iter.next( );
            if (curMsg.getBoard().getID( ) == boardID
                    && month.containsInMonth(curMsg.getCreateDate( ))) {
                msgs.add(curMsg);
            }
        }
        return msgs.iterator( );
    }

    /**
     * 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 {
        MessageSummary origMsg = getMessage(origMsgID);
        long msgID = getNextMessageID( );

        Message msg = new MessageImpl(msgID, new DayMonthYear( ), origMsg.getBoard( ),
                msgSubject, authorEmail, msgText, origMsgID);

        this.messageMap.put(new Long(msg.getID( )), msg);
        return msg;
    }

    /**
     * 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 boardSum = getBoardSummary(boardID);
        long msgID = getNextMessageID( );

        Message msg = new MessageImpl(msgID, new DayMonthYear( ), boardSum,
                msgSubject, authorEmail, msgText, -1);
        this.messageMap.put(new Long(msg.getID( )), msg);

        ((BoardSummaryImpl) boardSum).messageAdded(msg);

        return msg;
    }

    /**
     * @return an iterator of <code>BoardSummary</code> objects.
     */
    public Iterator getAllBoards( ) throws DataException {
        return this.allBoards.iterator( );
    }

    public BoardSummary getBoardSummary(long boardID)
            throws DataException {
        Iterator iter = getAllBoards( );
        while (iter.hasNext( )) {
            BoardSummary curBoard = (BoardSummary) iter.next( );
            if (curBoard.getID( ) == boardID) {
                return curBoard;
            }
        }
        throw new DataException("Illegal boardID: " + boardID);
    }

    private synchronized static long getNextMessageID( ) {
        nextMessageID++;
        return nextMessageID;
    }
} 

package com.oreilly.forum.domain;

import java.util.*;

/**
 * An implementation of the Message interface.
 */
public class MessageImpl extends MessageSummaryImpl implements Message {
    private String text;

    /**
     * Construct a new instance of this class.
     */
    public MessageImpl(long id, DayMonthYear createDate,
            BoardSummary board, String subject, String authorEmail,
            String text, long inReplyTo) {
        super(id, createDate, board, subject, authorEmail, inReplyTo);
        this.text = text;
    }

    /**
     * @return the text of this message.
     */
    public String getText( ) {
        return this.text;
    }
} 

package com.oreilly.forum.domain;

import java.util.*;

/**
 * Implementation of the MessageSummary interface.
 */
public class MessageSummaryImpl implements MessageSummary {
    private long id;
    private BoardSummary board;
    private String subject;
    private String authorEmail;
    private DayMonthYear createDate;
    private long inReplyTo;

    public MessageSummaryImpl(long id, DayMonthYear createDate,
            BoardSummary board, String subject, String authorEmail,
            long inReplyTo) {
        this.id = id;
        this.createDate = createDate;
        this.board = board;
        this.subject = subject;
        this.authorEmail = authorEmail;
        this.inReplyTo = inReplyTo;
    }

    public long getInReplyTo( ) {
        return this.inReplyTo;
    }

    public long getID( ) {
        return this.id;
    }

    public DayMonthYear getCreateDate( ) {
        return this.createDate;
    }

    public BoardSummary getBoard( ) {
        return this.board;
    }

    public String getSubject( ) {
        return this.subject;
    }

    public String getAuthorEmail( ) {
        return this.authorEmail;
    }

    public boolean equals(Object obj) {
        if (obj instanceof MessageSummaryImpl) {
            MessageSummaryImpl rhs = (MessageSummaryImpl) obj;
            return this.id == rhs.id;
        }
        return false;
    }

    public int hashCode( ) {
        return (int) this.id;
    }

    /**
     * Sorts by create date followed by message subject.
     */
    public int compareTo(Object obj) {
        if (this == obj) {
            return 0;
        }
        MessageSummaryImpl rhs = (MessageSummaryImpl) obj;

        int comparison = this.createDate.compareTo(rhs.createDate);
        if (comparison != 0) {
            return comparison;
        }

        comparison = this.subject.compareTo(rhs.subject);
        if (comparison != 0) {
            return comparison;
        }

        return 0;
    }
} 

package com.oreilly.forum.domain;

import java.io.Serializable;
import java.util.*;

/**
 * Represents a month and a year.
 */
public class MonthYear implements Comparable, Serializable {
    private int month;
    private int year;

    /**
     * Construct a new object representing the current instant in time.
     */
    public MonthYear( ) {
        this(new Date( ));
    }

    /**
     * Construct a new object with the given date.
     */
    public MonthYear(Date date) {
        this(DateUtil.getMonth(date), DateUtil.getYear(date));
    }

    /**
     * Construct a new object with the given month and year.
     * @param month a zero-based month, just like java.util.Calendar.
     */
    public MonthYear(int month, int year) {
        this.month = month;
        this.year = year;
    }

    /**
     * Compare this MonthYear object to another.
     */
    public int compareTo(Object obj) {
        MonthYear rhs = (MonthYear) obj;
        // first compare year
        if (this.year < rhs.year) {
            return -1;
        } else if (this.year > rhs.year) {
            return 1;
        }
        // then month
        if (this.month < rhs.month) {
            return -1;
        } else if (this.month > rhs.month) {
            return 1;
        }

        return 0;
    }

    /**
     * @return true if the specified date occurs sometime during this month.
     */
    public boolean containsInMonth(DayMonthYear date) {
        return date.getMonth( ) == this.month
                && date.getYear( ) == this.year;
    }

    /**
     * @return the month number, starting with 0 for January.
     */
    public int getMonth( ) {
        return this.month;
    }

    /**
     * @return the year number.
     */
    public int getYear( ) {
        return this.year;
    }

    public boolean equals(Object obj) {
        if (obj instanceof MonthYear) {
            MonthYear rhs = (MonthYear) obj;
            return this.month == rhs.month
                    && this.year == rhs.year;
        }
        return false;
    }

    public int hashCode( ) {
        return this.month ^ this.year;
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<!--
***********************************************************
** viewMsg.xslt
**
** Shows details for a specific message.
***********************************************************
-->
<xsl:stylesheet version="1.0" 
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:import href="utils.xslt"/>
  <xsl:param name="rootDir" select="'../docroot/'"/>
  <xsl:output method="xml" version="1.0" encoding="UTF-8" 
    indent="yes" 
    doctype-public="-//W3C//DTD XHTML 1.0 Strict//EN" 
    doctype-system="http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"/>
    
   <!--
  **********************************************************
  ** Create the XHTML web page
  *******************************************************-->
  <xsl:template match="/">
    <html xmlns="http://www.w3.org/1999/xhtml">
      <head>
        <title>View Message</title>
        <link href="{$rootDir}forum.css" 
            rel="stylesheet" type="text/css"/>
      </head>
      <body>
        <div class="box1">
          <h1>View Message</h1>
          <div>
            <xsl:value-of select="message/board/name"/>
          </div>
        </div>
        <!-- ===== Quick Actions ====== -->
        <h3>Quick Actions</h3>
        <ul>
          <li>Return to 
                           <!-- long line wrapped -->
          <a href="viewMonth?boardID={message/board/@id}&amp;month={
               message/@month}&amp;year={message/@year}">
              <xsl:call-template name="utils.printLongMonthName">
                <xsl:with-param name="monthNumber" select="message/@month"/>
              </xsl:call-template>,
          <xsl:value-of select="message/@year"/>
            </a> messages for <xsl:value-of select="message/board/name"/>
          </li>
          <li>Return to the <a href="home">home page</a>
          </li>
          <li>
            <a href="postMsg?mode=replyToMsg&amp;origMsgID={message/@id}">Reply</a> 
              to this message</li>
        </ul>
        <h3>Message</h3>
        <div class="box2">
          <xsl:apply-templates select="message"/>
        </div>
      </body>
    </html>
  </xsl:template>
  
  <!--
  **********************************************************
  ** Show details for the <message> element
  *******************************************************-->
  <xsl:template match="message">
    <div>
      <div style="font-weight: bold;">
        <xsl:value-of select="subject"/>
      </div>
      <xsl:text> posted by </xsl:text>
      <a href="mailto:{authorEmail}">
        <xsl:value-of select="authorEmail"/>
      </a>
      <xsl:text> on </xsl:text>
      <xsl:call-template name="utils.printShortMonthName">
        <xsl:with-param name="monthNumber" select="@month"/>
      </xsl:call-template>
      <xsl:text> </xsl:text>
      <xsl:value-of select="@day"/>
      <xsl:text>, </xsl:text>
      <xsl:value-of select="@year"/>
      <xsl:apply-templates select="inResponseTo"/>
    </div>
    <pre>
      <xsl:value-of select="text"/>
    </pre>
  </xsl:template>
  
  <!--
  **********************************************************
  ** Show a link to the message that this one is in
  ** response to.
  *******************************************************-->
  <xsl:template match="inResponseTo">
    <div style="text-indent: 2em;">
      <xsl:text>In response to </xsl:text>
      <a href="viewMsg?msgID={@id}">
        <xsl:value-of select="subject"/>
      </a>
    </div>
  </xsl:template>
</xsl:stylesheet>