dbthreaditerator.java

Jive Forums 1.0 src

/**
 * DbThreadIterator.java
 * August 12, 2000
 *
 * Copyright (C) 2000 CoolServlets.com. All rights reserved.
 *
 * ===================================================================
 * The Apache Software License, Version 1.1
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by
 *        CoolServlets.com (http://www.coolservlets.com)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Jive" and "CoolServlets.com" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please
 *    contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Jive",
 *    nor may "Jive" appear in their name, without prior written
 *    permission of CoolServlets.com.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL COOLSERVLETS.COM OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of CoolServlets.com. For more information
 * on CoolServlets.com, please see <http://www.coolservlets.com>.
 */
 
package com.coolservlets.forum.database;

import java.util.*;
//JDK1.1// import com.sun.java.util.collections.*;
import java.sql.*;

import com.coolservlets.forum.*;
import com.coolservlets.util.*;

/**
 * Database implementation of Iterator for ForumMesages in a ForumThread.
 */
public class DbThreadIterator implements Iterator, ListIterator {

    /** DATABASE QUERIES **/
    private static final String MESSAGE_COUNT =
        "SELECT count(messageID) FROM jiveMessage WHERE threadID=?";
    private static final String GET_MESSAGES =
        "SELECT messageID, creationDate FROM jiveMessage WHERE threadID=? " +
        "ORDER BY creationDate ASC";

    private ForumThread thread;
    private int [] messages;
    private int currentIndex = -1;

    protected DbThreadIterator(ForumThread thread) {
        this.thread = thread;
        Connection con = null;
        PreparedStatement pstmt = null;
        try {
            con = DbConnectionManager.getConnection();
            pstmt = con.prepareStatement(MESSAGE_COUNT);
            pstmt.setInt(1, thread.getID());
            ResultSet rs = pstmt.executeQuery();
            rs.next();
            messages = new int[rs.getInt(1)];
            pstmt.close();

            pstmt = con.prepareStatement(GET_MESSAGES);
            pstmt.setInt(1, thread.getID());
            rs = pstmt.executeQuery();
            for (int i=0; i<messages.length; i++) {
                rs.next();
                messages[i] = rs.getInt("messageID");
            }
        }
        catch( SQLException sqle ) {
            System.err.println("Error in DbThreadIterator:constructor()-" + sqle);
        }
        finally {
            try {  pstmt.close(); }
            catch (Exception e) { e.printStackTrace(); }
            try {  con.close();   }
            catch (Exception e) { e.printStackTrace(); }
        }
    }

    protected DbThreadIterator(ForumThread thread, int startIndex, int numResults)
    {
        this.thread = thread;

        int[] tempMessages = new int[numResults];
        //It's very possible that there might not be as many messages to get
        //as we requested. Therefore, we keep track of how many messages we
        //get by keeping a messageCount.
        int messageCount = 0;

        Connection con = null;
        PreparedStatement pstmt = null;

        try {
            con = DbConnectionManager.getConnection();
            pstmt = con.prepareStatement(GET_MESSAGES);
            pstmt.setInt(1, thread.getID());
            ResultSet rs = pstmt.executeQuery();            
            //Move to start of index
            for (int i=0; i<startIndex; i++) {
                rs.next();
            }
            //Now read in desired number of results
            for (int i=0; i<numResults; i++) {
                if (rs.next()) {
                    tempMessages[messageCount] = rs.getInt("messageID");
                    messageCount++;
                }
                else {
                    break;
                }
            }
        }
        catch( SQLException sqle ) {
            System.err.println("Error in DbThreadIterator:constructor()-" + sqle);
        }
        finally {
            try {  pstmt.close(); }
            catch (Exception e) { e.printStackTrace(); }
            try {  con.close();   }
            catch (Exception e) { e.printStackTrace(); }
        }
        messages = new int[messageCount];
        for (int i=0; i<messageCount; i++) {
            messages[i] = tempMessages[i];
        }
    }

    /**
     * Returns true if there is a next message in the list.
     */
    public boolean hasNext() {
        return (currentIndex+1 < messages.length);
    }

    /**
     * Returns true if there is a previous message in the list.
     */
    public boolean hasPrevious() {
        return (currentIndex > 0);
    }

    /**
     * Returns the next message.
     */
    public Object next() throws java.util.NoSuchElementException {
        ForumMessage message = null;
        currentIndex++;
        if (currentIndex >= messages.length) {
            throw new java.util.NoSuchElementException();
        }
        try {
            message = thread.getMessage(messages[currentIndex]);
        }
        catch (ForumMessageNotFoundException mnfe) {
            System.err.println(mnfe);
            throw new java.util.NoSuchElementException();
        }
        return message;
    }

    public int nextIndex() {
        return currentIndex+1;
    }

    /**
     * Returns the previous message.
     */
    public Object previous() throws java.util.NoSuchElementException {
        ForumMessage message = null;
        currentIndex--;
        if (currentIndex < 0) {
            currentIndex++;
            throw new java.util.NoSuchElementException();
        }
        try {
            message = thread.getMessage(messages[currentIndex]);
        }
        catch (ForumMessageNotFoundException mnfe) {
            System.err.println(mnfe);
            throw new java.util.NoSuchElementException();
        }
        return message;
    }

    public int previousIndex() {
        return currentIndex-1;
    }

    /**
     * Not supported for security reasons. Use the deleteMessage method in the
     * ForumThread class instead.
     *
     * @see ForumThread#deleteMessage(ForumMessage)
     */
    public void add(Object o) throws UnsupportedOperationException {
        throw new UnsupportedOperationException();
    }

    /**
     * Not supported for security reasons. Use the deleteMessage method in the
     * ForumThread class instead.
     *
     * @see ForumThread#deleteMessage(ForumMessage)
     */
    public void remove() throws UnsupportedOperationException {
        throw new UnsupportedOperationException();
    }

    /**
     * Not supported for security reasons. Use the methods in the
     * ForumThread class instead.
     *
     * @see ForumThread
     */
    public void set(Object o) throws UnsupportedOperationException {
        throw new UnsupportedOperationException();
    }
}