iit.cs570.assign1.web.managedbean.BM25Searcher.java Source code

Introduction

Here is the source code for iit.cs570.assign1.web.managedbean.BM25Searcher.java

Source

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package iit.cs570.assign1.web.managedbean;

import iit.cs570.assign1.web.util.TheCrawlersConstants;
import java.io.File;
import java.io.IOException;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.index.CorruptIndexException;
import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.queryparser.classic.ParseException;
import org.apache.lucene.queryparser.classic.QueryParser;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.search.similarities.BM25Similarity;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;
import org.apache.lucene.util.Version;

import iit.cs570.assign1.web.interfaces.*;
import org.apache.lucene.search.highlight.Highlighter;
import org.apache.lucene.search.highlight.InvalidTokenOffsetsException;
import org.apache.lucene.search.highlight.QueryScorer;
import org.apache.lucene.search.highlight.Scorer;

/**
 *
 * @author Neelesh
 */
public class BM25Searcher implements SearcherIntf {

    IndexSearcher indexSearcher;
    QueryParser queryParser;
    Query query;
    IndexReader reader;

    public BM25Searcher(String indexDirectoryPath) throws IOException {
        Directory indexDirectory = FSDirectory.open(new File(indexDirectoryPath));
        reader = DirectoryReader.open(indexDirectory);
        indexSearcher = new IndexSearcher(reader);
        indexSearcher.setSimilarity(new BM25Similarity());
        queryParser = new QueryParser(Version.LUCENE_42, TheCrawlersConstants.TEXT,
                new StandardAnalyzer(Version.LUCENE_42));
    }

    @Override
    public TopDocs search(String searchQuery) throws IOException, ParseException {
        query = queryParser.parse(searchQuery);
        return indexSearcher.search(query, TheCrawlersConstants.MAX_SEARCH);
    }

    @Override
    public Document getDocument(ScoreDoc scoreDoc) throws CorruptIndexException, IOException {
        return indexSearcher.doc(scoreDoc.doc);
    }

    @Override
    public void close() throws IOException {
        reader.close();
    }

    @Override
    public String getBestFragment(Document doc) throws IOException, InvalidTokenOffsetsException {
        Scorer scorer = new QueryScorer(query);
        Highlighter highlighter = new Highlighter(scorer);
        return highlighter.getBestFragment(new StandardAnalyzer(Version.LUCENE_42), TheCrawlersConstants.TEXT,
                doc.get(TheCrawlersConstants.TEXT));
    }
}