KEAFilterBank.java

/**
 *  OpenKM, Open Document Management System (http://www.openkm.com)
 *  Copyright (c) 2006-2011  Paco Avila & Josep Llort
 *
 *  No bytes were intentionally harmed during the development of this application.
 *
 *  This program 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.
 *  
 *  This program 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 this program; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

package com.openkm.kea.metadata;

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.util.Date;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.openkm.kea.filter.KEAFilter;
import com.openkm.kea.stemmers.SremovalStemmer;
import com.openkm.kea.stemmers.Stemmer;
import com.openkm.kea.stopwords.Stopwords;

/**
 * KEAFilterBank
 * 
 * @author jllort
 *
 */
public class KEAFilterBank {

	private static Logger log = LoggerFactory.getLogger(KEAFilterBank.class);

    private static KEAFilterBank instance;
    private KEAFilter filter;

    /**
     * KEAFilterBank
     * 
     * @return
     * @throws MetadataExtractionException
     */
    public static synchronized KEAFilterBank getInstance() throws MetadataExtractionException {
        if (instance == null) {
            instance = new KEAFilterBank();
        }
        return instance;
    }

    /**
     * KEAFilterBank
     * 
     * @throws MetadataExtractionException
     */
    private KEAFilterBank() throws MetadataExtractionException {
        Date start = new Date();
        
        String modelPath = WorkspaceHelper.KEA_MODEL_PATH;
        String vocabularyPath = WorkspaceHelper.RDF_SKOS_VOVABULARY_PATH;
        int numPhrases = 5;
        
        String className = WorkspaceHelper.KEA_STOPWORDS_CLASSNAME;
        Stopwords stopwords = null;
		if (className != null) {
			try {
				Class<?> clazz = Class.forName(className);
				stopwords = (Stopwords) clazz.newInstance();
			} catch (Exception e) {
				log.error("Error creating class instance", e);
			}
		}
        
        filter = buildFilter(modelPath, vocabularyPath, "skos", WorkspaceHelper.KEA_LANGUAGE, new SremovalStemmer(), stopwords, numPhrases);
        
        Date stop = new Date();
        long time = (stop.getTime() - start.getTime());
        log.info("KEA filters built in " + time + "ms");
    }

    /**
     * getFilter
     * 
     * @return
     * @throws MetadataExtractionException
     */
    public static KEAFilter getFilter() throws MetadataExtractionException {
        return getInstance().filter;
    }
    
    /**
     * buildFilter
     * 
     * @param modelPath
     * @param vocabularyPath
     * @param vocabularyFormat
     * @param language
     * @param stemmer
     * @param stopwords
     * @param numPhrases
     * 
     * @return
     * @throws MetadataExtractionException
     */
    private KEAFilter buildFilter(String modelPath, String vocabularyPath, String vocabularyFormat,
    							  String language, Stemmer stemmer, Stopwords stopwords, int numPhrases) throws MetadataExtractionException {

        KEAFilter newFilter = null;
        try {
            BufferedInputStream bis = new BufferedInputStream(new FileInputStream(modelPath));
            ObjectInputStream ois = new ObjectInputStream(bis);
            newFilter = (KEAFilter) ois.readObject();

            newFilter.setVocabulary(vocabularyPath);
            newFilter.setVocabularyFormat(vocabularyFormat);
            newFilter.setDocumentLanguage(language);
            newFilter.setStemmer(stemmer);
            newFilter.setStopwords(stopwords);
            newFilter.loadThesaurus(stemmer,stopwords);
            newFilter.setNumPhrases(numPhrases);

            return newFilter;

        } catch (FileNotFoundException e) {
            log.error("Unable to find KEA model file");
            log.error(e.getMessage(), e);
            throw new MetadataExtractionException("Subject Extraction failed (see trace for details.");
        } catch (IOException e) {
            log.error("Cannot read KEA model from stream");
            log.error(e.getMessage(), e);
            throw new MetadataExtractionException("Subject Extraction failed (see trace for source.");
        } catch (ClassNotFoundException e) {
            log.error("Class cast- KEA model.",e);
            log.error(e.getMessage(), e);
            throw new MetadataExtractionException("Subject Extraction failed (see trace for source.");
        } catch (Throwable e) {
        	log.error("Unexpected error with model");
        	log.error(e.getMessage(), e);
            throw new MetadataExtractionException("Subject Extraction failed (see trace for source.");
        }
    }

}