Lucene example source code file (PayloadHelper.java)

This example Lucene source code file (PayloadHelper.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Lucene tags/keywords

document, field, field, indexwriter, io, ioexception, override, payload, payload, payloadanalyzer, payloadfilter, payloadfilter, string, string, tokenstream, util

The Lucene PayloadHelper.java source code

package org.apache.lucene.search.payloads;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.IOException;
import java.io.Reader;
import java.util.Random;

import org.apache.lucene.analysis.*;
import org.apache.lucene.analysis.tokenattributes.PayloadAttribute;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.util.LuceneTestCase;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.Payload;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Similarity;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.MockDirectoryWrapper;
import org.apache.lucene.store.RAMDirectory;
import org.apache.lucene.util.English;

import static org.apache.lucene.util.LuceneTestCase.TEST_VERSION_CURRENT;

/**
 *
 *
 **/
public class PayloadHelper {

  private byte[] payloadField = new byte[]{1};
  private byte[] payloadMultiField1 = new byte[]{2};
  private byte[] payloadMultiField2 = new byte[]{4};
  public static final String NO_PAYLOAD_FIELD = "noPayloadField";
  public static final String MULTI_FIELD = "multiField";
  public static final String FIELD = "field";

  public IndexReader reader;

  public final class PayloadAnalyzer extends Analyzer {



    @Override
    public TokenStream tokenStream(String fieldName, Reader reader) {
      TokenStream result = new LowerCaseTokenizer(TEST_VERSION_CURRENT, reader);
      result = new PayloadFilter(result, fieldName);
      return result;
    }
  }

  public final class PayloadFilter extends TokenFilter {
    String fieldName;
    int numSeen = 0;
    PayloadAttribute payloadAtt;
    
    public PayloadFilter(TokenStream input, String fieldName) {
      super(input);
      this.fieldName = fieldName;
      payloadAtt = addAttribute(PayloadAttribute.class);
    }

    @Override
    public boolean incrementToken() throws IOException {
      
      if (input.incrementToken()) {
        if (fieldName.equals(FIELD))
        {
          payloadAtt.setPayload(new Payload(payloadField));
        }
        else if (fieldName.equals(MULTI_FIELD))
        {
          if (numSeen  % 2 == 0)
          {
            payloadAtt.setPayload(new Payload(payloadMultiField1));
          }
          else
          {
            payloadAtt.setPayload(new Payload(payloadMultiField2));
          }
          numSeen++;
        }
        return true;
      }
      return false;
    }
  }

  /**
   * Sets up a RAMDirectory, and adds documents (using English.intToEnglish()) with two fields: field and multiField
   * and analyzes them using the PayloadAnalyzer
   * @param similarity The Similarity class to use in the Searcher
   * @param numDocs The num docs to add
   * @return An IndexSearcher
   * @throws IOException
   */
  // TODO: randomize
  public IndexSearcher setUp(Random random, Similarity similarity, int numDocs) throws IOException {
    Directory directory = new MockDirectoryWrapper(random, new RAMDirectory());
    PayloadAnalyzer analyzer = new PayloadAnalyzer();
    IndexWriter writer = new IndexWriter(directory, new IndexWriterConfig(
        TEST_VERSION_CURRENT, analyzer).setSimilarity(similarity));
    // writer.infoStream = System.out;
    for (int i = 0; i < numDocs; i++) {
      Document doc = new Document();
      doc.add(new Field(FIELD, English.intToEnglish(i), Field.Store.YES, Field.Index.ANALYZED));
      doc.add(new Field(MULTI_FIELD, English.intToEnglish(i) + "  " + English.intToEnglish(i), Field.Store.YES, Field.Index.ANALYZED));
      doc.add(new Field(NO_PAYLOAD_FIELD, English.intToEnglish(i), Field.Store.YES, Field.Index.ANALYZED));
      writer.addDocument(doc);
    }
    reader = IndexReader.open(writer, true);
    writer.close();

    IndexSearcher searcher = LuceneTestCase.newSearcher(reader);
    searcher.setSimilarity(similarity);
    return searcher;
  }

  public void tearDown() throws Exception {
    reader.close();
  }
}