dbsearchindexer.java

这是学习Java必须读懂两套源代码

/**
 * Copyright (C) 2001 Yasna.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
 *        Yasna.com (http://www.yasna.com)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Yazd" and "Yasna.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 "Yazd",
 *    nor may "Yazd" appear in their name, without prior written
 *    permission of Yasna.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 YASNA.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 Yasna.com. For more information
 * on Yasna.com, please see <http://www.yasna.com>.
 */

/**
 * 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.Yasna.forum.database;

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

import com.lucene.document.*;
import com.lucene.analysis.*;
import com.lucene.analysis.standard.*;
import com.lucene.index.*;
import com.lucene.store.*;

import com.Yasna.forum.*;
import com.Yasna.util.*;

/**
 * Database implementation of SearchIndexer using the Lucene search package.
 *
 * Search indexes are stored in the "search" subdirectory of directory pointed to
 * by the Yazd property "yazdHome".
 */
public class DbSearchIndexer extends Thread implements SearchIndexer{

    /** DATABASE QUERIES **/
    //private static final String MESSAGES_BEFORE_DATE =
    //  "SELECT messageID FROM yazdMessage WHERE modifiedDate < ?";
    private static final String MESSAGES_BEFORE_DATE =
        "SELECT messageID, userID, yazdMessage.threadID, forumID, " +
        "subject, body, yazdMessage.creationDate " +
        "FROM yazdMessage, yazdThread WHERE yazdMessage.threadID=yazdThread.threadID " +
        "AND yazdMessage.modifiedDate < ?";
    private static final String MESSAGES_BEFORE_DATE_COUNT =
        "SELECT count(messageID) FROM yazdMessage WHERE modifiedDate < ?";
    private static final String MESSAGES_SINCE_DATE =
        "SELECT messageID FROM yazdMessage WHERE modifiedDate > ? " +
        "AND modifiedDate < ?";
    private static final String MESSAGES_SINCE_DATE_COUNT =
        "SELECT count(messageID) FROM yazdMessage WHERE modifiedDate > ? " +
        "AND modifiedDate < ?";
    private static final String LOAD_MESSAGE =
        "SELECT subject, body, userID, yazdMessage.threadID, forumID, " +
        "yazdMessage.creationDate FROM yazdMessage, yazdThread WHERE " +
        "yazdMessage.threadID=yazdThread.threadID AND yazdMessage.messageID=?";

    /**
     * Path to where index is stored.
     */
    private static String indexPath = null;

    /**
     * Time constants (in milleseconds)
     */
    private static final long MINUTE = 1000 * 60;
    private static final long HOUR = MINUTE * 60;

    /**
     * Maintains the amount of time that should elapse until the next index.
     */
    private long updateInterval;

    /**
     * Maintains the time that the last index took place.
     */
    private long lastIndexed;

    /**
     * Indicates whether auto-indexing should be on or off. When on, an update
     * will be run at the "updateInterval".
     */
    private boolean autoIndex = true;

    /**
     * ForumFactory so that we can load message objects based on their ID.
     */
    private DbForumFactory factory;

    /**
     * Lock so that only one indexing function can be executed at once. Not
     * locking could impact the database integrity. Therefore, in a cluster of
     * Yazd servers all pointed at the same db, only one indexer should be
     * running once.
     */
    private Object indexLock = new Object();

    private static Analyzer analyzer = new StopAnalyzer();

    /**
     * Creates a new DbSearchIndexer. It attempts to load properties for
     * the update interval and when the last index occured from the Yazd 
     * properties then starts the indexing thread.
     */
    public DbSearchIndexer(DbForumFactory factory) {
        this.factory = factory;

        //Default to performing updates ever 10 minutes.
        updateInterval = 10 * MINUTE;
        //If the update interval property exists, use that
        String updInterval = PropertyManager.getProperty("DbSearchIndexer.updateInterval");
        try {
            updateInterval = Long.parseLong(updInterval);
        }
        catch (Exception e) { /* ignore */ }

        //Attempt to get the last updated time from the Yazd properties
        String lastInd = PropertyManager.getProperty("DbSearchIndexer.lastIndexed");
        try {
            lastIndexed = Long.parseLong(lastInd);
        }
        catch (Exception e) {
            //Something went wrong. Therefore, set lastIndexed far into the past
            //so that we'll do a full index.
            lastIndexed = 0;
        }
        //Make this a daemon thread.
        this.setDaemon(true);
        //Start the indexing thread.
        start();
    }

    public int getHoursUpdateInterval() {
        return (int)(updateInterval / HOUR);
    }

    public int getMinutesUpdateInterval() {
        return (int)((updateInterval - getHoursUpdateInterval()*HOUR) / MINUTE);
    }

    public void setUpdateInterval(int minutes, int hours) {
        updateInterval = (minutes * MINUTE) + (hours * HOUR);
        //Save it to the properties
        PropertyManager.setProperty("DbSearchIndexer.updateInterval", ""+updateInterval);
    }

    public java.util.Date getLastIndexedDate() {
        return new java.util.Date(lastIndexed);
    }

    public boolean isAutoIndexEnabled() {
        return autoIndex;
    }

    public void setAutoIndexEnabled(boolean value) {
        autoIndex = value;
    }

    public void addToIndex(ForumMessage message) {
        //acquire the index lock so that no other indexing operations
        //are performed.
        synchronized (indexLock) {
            IndexWriter writer = null;
            try {
                writer = getWriter(false);
                addMessageToIndex(writer, message.getID(),
                    message.getUnfilteredSubject(), message.getUnfilteredBody(),
                    message.getUser().getID(), message.getForumThread().getID(),
                    message.getForumThread().getForum().getID(),
                    message.getCreationDate()
                );
            }
            catch (IOException ioe) {
                ioe.printStackTrace();
            }
            finally{
                try { writer.close(); }
                catch (Exception e) { }
            }
        }
    }

    public void removeFromIndex(ForumMessage message) {
        //acquire the index lock so that no other indexing operations
        //are performed.
        synchronized (indexLock) {
            try {
                int [] toDelete = new int [] { message.getID() };
                deleteMessagesFromIndex(toDelete);
            }
            catch (IOException ioe) {
                ioe.printStackTrace();
            }
        }
    }

    public void updateIndex() {
        //acquire the index lock so that no other indexing operations
        //are performed.
        synchronized (indexLock) {
            long now = System.currentTimeMillis();
            updateIndex(lastIndexed, now);
            lastIndexed = now;
            //Save the time as a Yazd property.
            PropertyManager.setProperty("DbSearchIndexer.lastIndexed",
                "" + lastIndexed);
        }
    }

    public void rebuildIndex() {
        //acquire the index lock so that no other indexing operations
        //are performed.
        synchronized (indexLock) {
            long now = System.currentTimeMillis();
            rebuildIndex(now);
            lastIndexed = now;
            //Save the time as a Yazd property.
            PropertyManager.setProperty("DbSearchIndexer.lastIndexed",
                "" + lastIndexed);