Java tutorial
/* This file is part of Cyclos (www.cyclos.org). A project of the Social Trade Organisation (www.socialtrade.org). Cyclos is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. Cyclos is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with Cyclos; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ package nl.strohalm.cyclos.utils.lucene; import java.util.ArrayList; import java.util.Collections; import java.util.Iterator; import java.util.List; import nl.strohalm.cyclos.dao.FetchDAO; import nl.strohalm.cyclos.entities.Entity; import nl.strohalm.cyclos.entities.Indexable; import nl.strohalm.cyclos.entities.Relationship; import nl.strohalm.cyclos.entities.exceptions.DaoException; import nl.strohalm.cyclos.entities.exceptions.EntityNotFoundException; import nl.strohalm.cyclos.exceptions.ApplicationException; import nl.strohalm.cyclos.utils.DataIteratorHelper; import nl.strohalm.cyclos.utils.EntityHelper; import nl.strohalm.cyclos.utils.IteratorListImpl; import nl.strohalm.cyclos.utils.query.PageImpl; import nl.strohalm.cyclos.utils.query.PageParameters; import nl.strohalm.cyclos.utils.query.QueryParameters.ResultType; import nl.strohalm.cyclos.utils.validation.ValidationException; import org.apache.commons.lang.ArrayUtils; import org.apache.lucene.document.Document; import org.apache.lucene.index.IndexReader; import org.apache.lucene.search.Filter; import org.apache.lucene.search.IndexSearcher; import org.apache.lucene.search.Query; import org.apache.lucene.search.ScoreDoc; import org.apache.lucene.search.Sort; import org.apache.lucene.search.TopDocs; import org.apache.lucene.search.TotalHitCountCollector; /** * Handler for entity queries using Lucene * @author luis */ public class LuceneQueryHandler { private IndexHandler indexHandler; private FetchDAO fetchDao; /** * Executes a lucene query */ public <E extends Entity & Indexable> List<E> executeQuery(final Class<E> entityType, final Query query, Filter filter, final Sort sort, final ResultType resultType, final PageParameters pageParameters, final Relationship... fetch) { if (filter instanceof Filters && !((Filters) filter).isValid()) { filter = null; } switch (resultType) { case ITERATOR: return iterator(entityType, query, filter, sort, pageParameters, fetch); default: return listOrPage(entityType, query, filter, sort, resultType, pageParameters, fetch); } } public void setFetchDao(final FetchDAO fetchDao) { this.fetchDao = fetchDao; } public void setIndexHandler(final IndexHandler indexHandler) { this.indexHandler = indexHandler; } public <E extends Entity & Indexable> E toEntity(final IndexReader reader, final int docId, final Class<E> entityType, final Relationship... fetch) { try { Document doc = reader.document(docId, IdFieldSelector.getInstance()); long id = Long.parseLong(doc.get("id")); E entity = EntityHelper.reference(entityType, id); entity = fetchDao.fetch(entity, fetch); return entity; } catch (EntityNotFoundException e) { return null; } catch (Exception e) { throw new DaoException(e); } } private <E extends Entity & Indexable> List<E> iterator(final Class<E> entityType, final Query query, final Filter filter, final Sort sort, final PageParameters pageParameters, final Relationship... fetch) { IndexSearcher searcher = null; // Prepare the parameters IndexReader reader; try { reader = indexHandler.openReader(entityType); } catch (final DaoException e) { // Probably index files don't exist return new IteratorListImpl<E>(Collections.<E>emptyList().iterator()); } final int firstResult = pageParameters == null ? 0 : pageParameters.getFirstResult(); int maxResults = (pageParameters == null || pageParameters.getMaxResults() == 0) ? Integer.MAX_VALUE : pageParameters.getMaxResults() + firstResult; try { // Run the search searcher = new IndexSearcher(reader); TopDocs topDocs; if (sort == null || ArrayUtils.isEmpty(sort.getSort())) { topDocs = searcher.search(query, filter, maxResults); } else { topDocs = searcher.search(query, filter, maxResults, sort); } // Open the iterator Iterator<E> iterator = new DocsIterator<E>(this, entityType, reader, topDocs, firstResult, fetch); DataIteratorHelper.registerOpen(iterator, false); // Wrap the iterator return new IteratorListImpl<E>(iterator); } catch (final Exception e) { throw new DaoException(e); } finally { try { searcher.close(); } catch (final Exception e) { // Silently ignore } } } private <E extends Entity & Indexable> List<E> listOrPage(final Class<E> entityType, final Query query, final Filter filter, final Sort sort, final ResultType resultType, final PageParameters pageParameters, final Relationship... fetch) { IndexSearcher searcher = null; // Prepare the parameters IndexReader reader; try { reader = indexHandler.openReader(entityType); } catch (final DaoException e) { // Probably index files don't exist return Collections.emptyList(); } final int firstResult = pageParameters == null ? 0 : pageParameters.getFirstResult(); int maxResults = pageParameters == null ? Integer.MAX_VALUE : pageParameters.getMaxResults() + firstResult; try { searcher = new IndexSearcher(reader); if (maxResults == 0 && resultType == ResultType.PAGE) { // We just want the total hit count. TotalHitCountCollector collector = new TotalHitCountCollector(); searcher.search(query, filter, collector); int totalHits = collector.getTotalHits(); return new PageImpl<E>(pageParameters, totalHits, Collections.<E>emptyList()); } else { if (maxResults == 0) { maxResults = Integer.MAX_VALUE; } // Run the search TopDocs topDocs; if (sort == null || ArrayUtils.isEmpty(sort.getSort())) { topDocs = searcher.search(query, filter, maxResults); } else { topDocs = searcher.search(query, filter, maxResults, sort); } // Build the list ScoreDoc[] scoreDocs = topDocs.scoreDocs; List<E> list = new ArrayList<E>(Math.min(firstResult, scoreDocs.length)); for (int i = firstResult; i < scoreDocs.length; i++) { ScoreDoc scoreDoc = scoreDocs[i]; E entity = toEntity(reader, scoreDoc.doc, entityType, fetch); if (entity != null) { list.add(entity); } } // When result type is page, get the additional data if (resultType == ResultType.PAGE) { list = new PageImpl<E>(pageParameters, topDocs.totalHits, list); } return list; } } catch (final EntityNotFoundException e) { throw new ValidationException("general.error.indexedRecordNotFound"); } catch (ApplicationException e) { throw e; } catch (final Exception e) { throw new DaoException(e); } finally { // Close resources try { searcher.close(); } catch (final Exception e) { // Silently ignore } try { reader.close(); } catch (final Exception e) { // Silently ignore } } } }