Lucene example source code file (KeywordTokenizer.java)

This example Lucene source code file (KeywordTokenizer.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

chartermattribute, default_buffer_size, io, ioexception, ioexception, keywordtokenizer, keywordtokenizer, offsetattribute, override, override, reader, reader, tokenizer

The Lucene KeywordTokenizer.java source code

package org.apache.lucene.analysis;

/**
 * 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 org.apache.lucene.analysis.tokenattributes.OffsetAttribute;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.util.AttributeSource;

/**
 * Emits the entire input as a single token.
 */
public final class KeywordTokenizer extends Tokenizer {
  
  private static final int DEFAULT_BUFFER_SIZE = 256;

  private boolean done = false;
  private int finalOffset;
  private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
  private OffsetAttribute offsetAtt = addAttribute(OffsetAttribute.class);
  
  public KeywordTokenizer(Reader input) {
    this(input, DEFAULT_BUFFER_SIZE);
  }

  public KeywordTokenizer(Reader input, int bufferSize) {
    super(input);
    termAtt.resizeBuffer(bufferSize);
  }

  public KeywordTokenizer(AttributeSource source, Reader input, int bufferSize) {
    super(source, input);
    termAtt.resizeBuffer(bufferSize);
  }

  public KeywordTokenizer(AttributeFactory factory, Reader input, int bufferSize) {
    super(factory, input);
    termAtt.resizeBuffer(bufferSize);
  }
  
  @Override
  public final boolean incrementToken() throws IOException {
    if (!done) {
      clearAttributes();
      done = true;
      int upto = 0;
      char[] buffer = termAtt.buffer();
      while (true) {
        final int length = input.read(buffer, upto, buffer.length-upto);
        if (length == -1) break;
        upto += length;
        if (upto == buffer.length)
          buffer = termAtt.resizeBuffer(1+buffer.length);
      }
      termAtt.setLength(upto);
      finalOffset = correctOffset(upto);
      offsetAtt.setOffset(correctOffset(0), finalOffset);
      return true;
    }
    return false;
  }
  
  @Override
  public final void end() {
    // set final offset 
    offsetAtt.setOffset(finalOffset, finalOffset);
  }

  @Override
  public void reset(Reader input) throws IOException {
    super.reset(input);
    this.done = false;
  }
}