Java tutorial
/** * Copyright (c) 2009 eXtensible Catalog Organization * * This program is free software; you can redistribute it and/or modify it under the terms of the MIT/X11 license. The text of the * license can be found at http://www.opensource.org/licenses/mit-license.php and copy of the license can be found on the project * website http://www.extensiblecatalog.org/. * */ package xc.mst.utils.index; import java.util.AbstractList; import java.util.ArrayList; import org.apache.log4j.Logger; import org.apache.solr.client.solrj.SolrQuery; import org.apache.solr.common.SolrDocumentList; import xc.mst.bo.record.Record; import xc.mst.constants.Constants; import xc.mst.dao.DatabaseConfigException; import xc.mst.manager.IndexException; import xc.mst.manager.record.RecordService; import xc.mst.scheduling.ServiceWorkerThread; import xc.mst.utils.MSTConfiguration; /** * List of Records retrieved from Solr. * * @author Sharmila Ranganathan */ public class Records extends AbstractList<Record> { /** * The maximum number of results to */ private static final int MAX_RESULTS = 2000; /** * An Object which manages the Solr index */ protected SolrIndexManager indexMgr = (SolrIndexManager) MSTConfiguration.getInstance() .getBean("SolrIndexManager"); /** * The current offset into the results of the query that are in the document list */ private int currentOffset = 0; /** * The row to start to get results from document list */ private int startRow = 0; /** * A list of documents from the query between results currentOffset and currentOffset+MAX_RESULTS */ private SolrDocumentList docs = null; /** * The query for which the RecordList was built */ private SolrQuery query = null; /** * The service used to get a record from a Lucene document */ private static RecordService service = (RecordService) MSTConfiguration.getInstance().getBean("RecordService"); /** * The number of elements in the list */ private int size = 0; /** * A reference to the logger for this class */ static Logger log = Logger.getLogger(Constants.LOGGER_GENERAL); /** * Constructs a RecordList around a Solr query. The docs returned by the query * are assumed to all be Record Objects * * @param query * The Solr query for which the RecordList was built */ public Records(SolrQuery query) throws IndexException { if (query != null) { this.query = query; query.setRows(MAX_RESULTS); query.setStart(currentOffset); docs = indexMgr.getDocumentList(query); size = (int) docs.getNumFound(); } } /** * Constructs a RecordList around a Solr query. The docs returned by the query * are assumed to all be Record Objects * * @param query * The Solr query for which the RecordList was built */ public Records(SolrQuery query, int numRowsToFetch) throws IndexException { if (query != null) { this.query = query; query.setRows(numRowsToFetch); query.setStart(currentOffset); docs = indexMgr.getDocumentList(query); size = (int) docs.getNumFound(); } } /** * Gets the record at a given index * * @param index * The index of the Record to get * @return The record at the specified index */ public Record get(int index) { try { if (query == null || size == 0) return null; if (index < size) { if (index < currentOffset + MAX_RESULTS) { if (currentOffset == 0) { return service.getRecordFromDocument(docs.get(index)); } else { return service.getRecordFromDocument(docs.get(index % currentOffset)); } /* * For every 100k start getting records from 0. Because the data is committed every 100k. */ } else if ((index) % 100000 == 0) { StringBuffer buf = new StringBuffer(); buf.append(query.getQuery()); for (String identifier : ServiceWorkerThread.getRunningService() .getUnprocessedErrorRecordIdentifiers()) { buf.append(" AND ").append("-").append(RecordService.FIELD_OAI_IDENTIFIER).append(":") .append(identifier.replaceAll(":", "\\\\:")); } query.setQuery(buf.toString()); query.setRows(MAX_RESULTS); currentOffset = currentOffset + MAX_RESULTS; startRow = 0; query.setStart(startRow); docs = indexMgr.getDocumentList(query); // Empty the error list so that redundant error record OAI identifiers are not added to query ServiceWorkerThread.getRunningService() .setUnprocessedErrorRecordIdentifiers(new ArrayList<String>()); if (currentOffset == 0) { return service.getRecordFromDocument(docs.get(index)); } else { return service.getRecordFromDocument(docs.get(index % currentOffset)); } } else { query.setRows(MAX_RESULTS); currentOffset = currentOffset + MAX_RESULTS; startRow = startRow + MAX_RESULTS; query.setStart(startRow); docs = indexMgr.getDocumentList(query); if (currentOffset == 0) { return service.getRecordFromDocument(docs.get(index)); } else { return service.getRecordFromDocument(docs.get(index % currentOffset)); } } } else { log.error("Index out of bounds exception for RecordList index " + index); return null; } } catch (DatabaseConfigException e) { log.error("Cannot connect to the database with the parameters from the config file.", e); return null; } catch (IndexException ie) { log.error("Cannot connect to Solr Server. Check the port in configuration file.", ie); return null; } catch (Exception e) { log.error("RecordList error at currentOffset = " + currentOffset + " and index= " + index, e); return null; } } /** * The set method is not used because RecordLists are read only. It is * only included because it is required to extend the AbstractList class. * * @throws UnsupportedOperationException * Whenever this method is called */ public Record set(int index, Record element) { throw new UnsupportedOperationException( "An attempt was made to set an element on a RecordList. RecordLists are read only."); } /** * Returns the size of the RecordList * * @return The size of the RecordList */ public int size() { return size; } }