com.knowledgebooks.rdf.implementation.LuceneRdfManager.java Source code

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Here is the source code for com.knowledgebooks.rdf.implementation.LuceneRdfManager.java

Source

package com.knowledgebooks.rdf.implementation;

import java.io.File;
import java.io.IOException;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.List;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.index.CorruptIndexException;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.queryParser.ParseException;
import org.apache.lucene.queryParser.QueryParser;
import org.apache.lucene.search.*;
import org.apache.lucene.store.FSDirectory;
import org.apache.lucene.util.Version;

/**
 * Wrapper class for an embedded Lucene index to support free text search of all
 * information sources that have been added.
 * <p/>
 * <p/>
 * Copyright 2002-2008 by Mark Watson. All rights reserved.
 * <p/>
 * This software is not public domain. It can be legally
 * used under either of the following licenses:
 * <p/>
 * 1. KnowledgeBooks.com Non Commercial Royality Free License<br/>
 * 2. KnowledgeBooks.com Commercial Use License
 * <p/>
 * see www.knowledgebooks.com for details
 */
public class LuceneRdfManager {
    private String data_store_file_root;

    /**
     * @param data_store_file_root
     * @throws java.lang.Exception
     */
    public LuceneRdfManager(String data_store_file_root) throws Exception {
        this.data_store_file_root = data_store_file_root;
    }

    /**
     * @throws java.io.IOException
     */
    public void close() throws IOException {
    }

    /**
     * @param subject
     * @param predicate
     * @param object
     * @throws org.apache.lucene.index.CorruptIndexException
     *
     * @throws java.io.IOException
     */
    public void addTripleToIndex(String subject, String predicate, String object) throws IOException {
        File index_dir = new File(data_store_file_root + "/lucene_index");
        writer = new IndexWriter(FSDirectory.open(index_dir), new StandardAnalyzer(Version.LUCENE_CURRENT),
                !index_dir.exists(), IndexWriter.MaxFieldLength.LIMITED);
        //File index_dir = new File(data_store_file_root + "/lucene_index");
        //writer = new IndexWriter(FSDirectory.open(index_dir), new StandardAnalyzer(Version.LUCENE_CURRENT), true, IndexWriter.MaxFieldLength.UNLIMITED);
        Document doc = new Document();
        doc.add(new Field("subject", subject, Field.Store.YES, Field.Index.NO));
        doc.add(new Field("predicate", predicate, Field.Store.YES, Field.Index.NO));
        doc.add(new Field("object", object, Field.Store.YES, Field.Index.ANALYZED));
        writer.addDocument(doc);
        writer.optimize();
        writer.close();
    }

    /**
     * @param search_query
     * @return
     * @throws org.apache.lucene.queryParser.ParseException
     *
     * @throws java.io.IOException
     */
    public List<List<String>> searchIndex(String search_query) throws ParseException, IOException {
        File index_dir = new File(data_store_file_root + "/lucene_index");
        reader = IndexReader.open(FSDirectory.open(index_dir), true);
        List<List<String>> ret = new ArrayList<List<String>>();
        Searcher searcher = new IndexSearcher(reader);

        Analyzer analyzer = new StandardAnalyzer(Version.LUCENE_CURRENT);
        QueryParser parser = new QueryParser(Version.LUCENE_CURRENT, "object", analyzer);
        Query query = parser.parse(search_query);

        TopScoreDocCollector collector = TopScoreDocCollector.create(10, false);
        searcher.search(query, collector);
        ScoreDoc[] hits = collector.topDocs().scoreDocs;

        for (int i = 0; i < hits.length; i += 1) {
            Document doc = searcher.doc(hits[i].doc);
            List<String> as2 = new ArrayList<String>(23);
            as2.add(doc.get("subject"));
            as2.add(doc.get("predicate"));
            as2.add(doc.get("object"));
            ret.add(as2);
        }
        reader.close();
        return ret;
    }

    private IndexWriter writer;
    private IndexReader reader;
}