Indexer.java

package edu.isi.karma.semantictypes.tfIdf;

import java.io.File;
import java.io.IOException;

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.document.StringField;
import org.apache.lucene.document.TextField;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.IndexWriterConfig.OpenMode;
import org.apache.lucene.index.IndexableField;
import org.apache.lucene.index.Term;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;
import org.apache.lucene.util.Version;

/**
 * This class is responsible for creation of an index, adding documents to the
 * index, committing changes
 * 
 * @author ramnandan
 * 
 */

public class Indexer {
	public static String CONTENT_FIELD_NAME = "content";
	public static String LABEL_FIELD_NAME = "label";

	private IndexWriter indexWriter = null;
	private Directory indexDirectory;

	public Indexer(String filepath) throws IOException {
		indexDirectory = FSDirectory.open(new File(filepath));
	}

	public void open() throws IOException {

		Analyzer analyzer = new StandardAnalyzer(Version.LUCENE_48);
		IndexWriterConfig config = new IndexWriterConfig(Version.LUCENE_48,
				analyzer);

		// Creates a new index if one does not exist,
		// otherwise opens the index and documents will be appended
		config.setOpenMode(OpenMode.CREATE_OR_APPEND);

		indexWriter = new IndexWriter(indexDirectory, config);
	}

	public void commit() throws IOException {
		indexWriter.commit();
	}
	
	public void close() throws IOException {
		try {
			indexWriter.close(false);
		} finally {
			if (IndexWriter.isLocked(indexDirectory)) {
				IndexWriter.unlock(indexDirectory);
			}
		}
	}

	public void addDocument(String content, String label) throws IOException {
		Document doc = new Document();
		doc.add(new TextField(CONTENT_FIELD_NAME, content, Field.Store.YES));
		doc.add(new StringField(LABEL_FIELD_NAME, label, Field.Store.YES));
		indexWriter.addDocument(doc);
	}

	public void updateDocument(IndexableField[] existingContent, String newContent, String label) throws IOException {
		/**
		 * @patch applied
		 * @author pranav and aditi
		 * @date 12th June 2015
		 * 
		 * 
		 */
		
		Document doc = new Document();
		for(IndexableField singleContent: existingContent){
			doc.add(singleContent);
		}
		doc.add(new TextField(CONTENT_FIELD_NAME, newContent, Field.Store.YES));
		doc.add(new StringField(LABEL_FIELD_NAME, label, Field.Store.YES));
		indexWriter.updateDocument(new Term(LABEL_FIELD_NAME, label), doc);
	}

	public void deleteAllDocuments() throws IOException {
		indexWriter.deleteAll();
	}

	public int getNumberOfDocuments() {
		return indexWriter.numDocs();
	}

	

}