harvest.java

dspace 用j2ee架构的一个数字图书馆.开源程序

/*
 * Harvest.java
 *
 * Version: $Revision: 1.14 $
 *
 * Date: $Date: 2005/10/31 19:44:13 $
 *
 * Copyright (c) 2002-2005, Hewlett-Packard Company and Massachusetts
 * Institute of Technology.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * - Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *
 * - 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.
 *
 * - Neither the name of the Hewlett-Packard Company nor the name of the
 * Massachusetts Institute of Technology nor the names of their
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS 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 THE COPYRIGHT
 * HOLDERS OR 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.
 */
package org.dspace.search;

import java.sql.SQLException;
import java.util.LinkedList;
import java.util.List;

import org.apache.log4j.Logger;
import org.dspace.content.Collection;
import org.dspace.content.DSpaceObject;
import org.dspace.content.Item;
import org.dspace.core.ConfigurationManager;
import org.dspace.core.Constants;
import org.dspace.core.Context;
import org.dspace.core.LogManager;
import org.dspace.handle.HandleManager;
import org.dspace.storage.rdbms.DatabaseManager;
import org.dspace.storage.rdbms.TableRow;
import org.dspace.storage.rdbms.TableRowIterator;

/**
 * Utility class for extracting information about items, possibly just within a
 * certain community or collection, that have been created, modified or
 * withdrawn within a particular range of dates.
 * 
 * @author Robert Tansley
 * @version $Revision: 1.14 $
 */
public class Harvest
{
    /** log4j logger */
    private static Logger log = Logger.getLogger(Harvest.class);
    
    /**
     * Obtain information about items that have been created, modified or
     * withdrawn within a given date range. You can also specify 'offset' and
     * 'limit' so that a big harvest can be split up into smaller sections.
     * <P>
     * Note that dates are passed in the standard ISO8601 format used by DSpace
     * (and OAI-PMH).
     * <P>
     * FIXME: Assumes all in_archive items have public metadata
     * 
     * @param context
     *            DSpace context
     * @param scope
     *            a Collection, Community, or <code>null</code> indicating the scope is
     *            all of DSpace
     * @param startDate
     *            start of date range, or <code>null</code>
     * @param endDate
     *            end of date range, or <code>null</code>
     * @param offset
     *            for a partial harvest, the point in the overall list of
     *            matching items to start at. 0 means just start at the
     *            beginning.
     * @param limit
     *            the number of matching items to return in a partial harvest.
     *            Specify 0 to return the whole list (or the rest of the list if
     *            an offset was specified.)
     * @param items
     *            if <code>true</code> the <code>item</code> field of each
     *            <code>HarvestedItemInfo</code> object is filled out
     * @param collections
     *            if <code>true</code> the <code>collectionHandles</code>
     *            field of each <code>HarvestedItemInfo</code> object is
     *            filled out
     * @param withdrawn
     *            If <code>true</code>, information about withdrawn items is
     *            included
     * @return List of <code>HarvestedItemInfo</code> objects
     * @throws SQLException
     */
    public static List harvest(Context context, DSpaceObject scope,
            String startDate, String endDate, int offset, int limit,
            boolean items, boolean collections, boolean withdrawn)
            throws SQLException
    {
        // SQL to add to the list of tables after the SELECT
        String scopeTableSQL = "";

        // SQL to add to the WHERE clause of the query
        String scopeWhereSQL = "";

        if (scope != null)
        {
        	if (scope.getType() == Constants.COLLECTION)
        	{
        		scopeTableSQL = ", collection2item";
        		scopeWhereSQL = " AND collection2item.collection_id="
        						+ scope.getID()
        						+ " AND collection2item.item_id=handle.resource_id";
        	}
        	else if (scope.getType() == Constants.COMMUNITY)
        	{
        		scopeTableSQL = ", community2item";
        		scopeWhereSQL = " AND community2item.community_id="
								+ scope.getID()
								+ " AND community2item.item_id=handle.resource_id";
        	}
        }

        // Put together our query. Note there is no need for an
        // "in_archive=true" condition, we are using the existence of
        // Handles as our 'existence criterion'.
        String query = "SELECT handle.handle, handle.resource_id, item.withdrawn, item.last_modified FROM handle, item"
                + scopeTableSQL
                + " WHERE handle.resource_type_id="
                + Constants.ITEM
                + " AND handle.resource_id=item.item_id"
                + scopeWhereSQL;

        if (startDate != null)
        {
            if ("oracle".equals(ConfigurationManager.getProperty("db.name")))
            {
                query = query + " AND item.last_modified >= " 
                        + oracleTimeStampFromIsoString(startDate);
            }
            else //postgres
            {
                query = query + " AND item.last_modified >= '" + startDate + "'";
            }            
        }

        if (endDate != null)
        {
            /*
             * If the end date has seconds precision, e.g.:
             * 
             * 2004-04-29T13:45:43Z
             * 
             * we need to add 999 milliseconds to this. This is because SQL
             * TIMESTAMPs have millisecond precision, and so might have a value:
             * 
             * 2004-04-29T13:45:43.952Z
             * 
             * and so <= '2004-04-29T13:45:43Z' would not pick this up. Reading
             * things out of the database, TIMESTAMPs are rounded down, so the
             * above value would be read as '2004-04-29T13:45:43Z', and
             * therefore a caller would expect <= '2004-04-29T13:45:43Z' to
             * include that value.
             * 
             * Got that? ;-)
             */
            if (endDate.length() == 20)
            {
                endDate = endDate.substring(0, 19) + ".999Z";
            }

            if ("oracle".equals(ConfigurationManager.getProperty("db.name")))
            {
                query = query + " AND item.last_modified <= " 
                        + oracleTimeStampFromIsoString(endDate);
            }
            else //postgres
            {
                query = query + " AND item.last_modified <= '" + endDate + "'";
            }
        }

        if (withdrawn == false)
        {
            // Exclude withdrawn items
            if ("oracle".equals(ConfigurationManager.getProperty("db.name")))
            {
                query = query + " AND withdrawn=0";
            }
            else
            {
                // postgres uses booleans
                query = query + " AND withdrawn=false";
            }
        }

        // Order by item ID, so that for a given harvest the order will be
        // consistent. This is so that big harvests can be broken up into
        // several smaller operations (e.g. for OAI resumption tokens.)
        query = query + " ORDER BY handle.resource_id";

        log.debug(LogManager.getHeader(context, "harvest SQL", query));

        // Execute
        TableRowIterator tri = DatabaseManager.query(context, query);
        List infoObjects = new LinkedList();
        int index = 0;

        // Process results of query into HarvestedItemInfo objects
        while (tri.hasNext())
        {
            TableRow row = tri.next();

            /*
             * This conditional ensures that we only process items within any
             * constraints specified by 'offset' and 'limit' parameters.
             */
            if ((index >= offset)
                    && ((limit == 0) || (index < (offset + limit))))
            {
                HarvestedItemInfo itemInfo = new HarvestedItemInfo();
                
                itemInfo.context = context;
                itemInfo.handle = row.getStringColumn("handle");
                itemInfo.itemID = row.getIntColumn("resource_id");
                itemInfo.datestamp = row.getDateColumn("last_modified");
                itemInfo.withdrawn = row.getBooleanColumn("withdrawn");

                if (collections)
                {
                    fillCollections(context, itemInfo);
                }

                if (items)
                {
                    // Get the item
                    itemInfo.item = Item.find(context, itemInfo.itemID);
                }

                infoObjects.add(itemInfo);
            }

            index++;
        }

        return infoObjects;
    }

    /**
     * Get harvested item info for a single item. <code>item</code> field in
     * returned <code>HarvestedItemInfo</code> object is always filled out.
     * 
     * @param context
     *            DSpace context
     * @param handle
     *            Prefix-less Handle of item
     * @param collections
     *            if <code>true</code> the <code>collectionHandles</code>
     *            field of the <code>HarvestedItemInfo</code> object is filled
     *            out
     * 
     * @return <code>HarvestedItemInfo</code> object for the single item, or
     *         <code>null</code>
     * @throws SQLException
     */
    public static HarvestedItemInfo getSingle(Context context, String handle,
            boolean collections) throws SQLException
    {
        // FIXME: Assume Handle is item
        Item i = (Item) HandleManager.resolveToObject(context, handle);

        if (i == null)
        {
            return null;
        }

        // Fill out OAI info item object
        HarvestedItemInfo itemInfo = new HarvestedItemInfo();

        itemInfo.context = context;
        itemInfo.item = i;
        itemInfo.handle = handle;
        itemInfo.withdrawn = i.isWithdrawn();
        itemInfo.datestamp = i.getLastModified();
        itemInfo.itemID = i.getID();

        // Get the sets
        if (collections)
        {
            fillCollections(context, itemInfo);
        }

        return itemInfo;
    }

    /**
     * Fill out the containers field of the HarvestedItemInfo object
     * 
     * @param context
     *            DSpace context
     * @param itemInfo
     *            HarvestedItemInfo object to fill out
     * @throws SQLException
     */
    private static void fillCollections(Context context,
            HarvestedItemInfo itemInfo) throws SQLException
    {
        // Get the collection Handles from DB
        TableRowIterator colRows = DatabaseManager
                .query(
                        context,
                        "SELECT handle.handle FROM handle, collection2item WHERE handle.resource_type_id="
                                + Constants.COLLECTION
                                + " AND collection2item.collection_id=handle.resource_id AND collection2item.item_id = "
                                + itemInfo.itemID);

        // Chuck 'em in the itemInfo object
        itemInfo.collectionHandles = new LinkedList();

        while (colRows.hasNext())
        {
            TableRow r = colRows.next();
            itemInfo.collectionHandles.add(r.getStringColumn("handle"));
        }
    }
    
    /**
     * creates an oracle format timestamp from an ISO 8601-style string
     * @param isoDateString
     * @return oracle format timestamp String
     */
    private static String oracleTimeStampFromIsoString(String isoDateString)
    {
        String timeStampString;
        
        if (isoDateString.length() == 10)
        {
            timeStampString = "TO_TIMESTAMP('" + isoDateString + "T00:00:00" 
                                + "'," + "'YYYY-MM-DD\"T\"HH24:MI:SS')";
            
        } else if (isoDateString.length() == 19 )
        {
            timeStampString = "TO_TIMESTAMP('" + isoDateString  
                                + "','YYYY-MM-DD\"T\"HH24:MI:SS')";
        } else if (isoDateString.length() > 19)
        {
            timeStampString = "TO_TIMESTAMP('" + isoDateString  
                                + "','YYYY-MM-DD\"T\"HH24:MI:SS.FF\"Z\"')"; 
        } else
        {
            throw new IllegalArgumentException("argument does not seem to be in the expected ISO 8601 format");
        }
                                   
        return timeStampString;
    }

}