Lucene example source code file (Tokenizer.java)

This example Lucene source code file (Tokenizer.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

charstream, charstream, io, ioexception, ioexception, override, reader, reader, tokenizer, tokenizer, tokenstream

The Lucene Tokenizer.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 org.apache.lucene.util.AttributeSource;

import java.io.Reader;
import java.io.IOException;

/** A Tokenizer is a TokenStream whose input is a Reader.
  <p>
  This is an abstract class; subclasses must override {@link #incrementToken()}
  <p>
  NOTE: Subclasses overriding {@link #incrementToken()} must
  call {@link AttributeSource#clearAttributes()} before
  setting attributes.
 */
public abstract class Tokenizer extends TokenStream {
  /** The text source for this Tokenizer. */
  protected Reader input;

  /** Construct a tokenizer with null input. */
  protected Tokenizer() {}
  
  /** Construct a token stream processing the given input. */
  protected Tokenizer(Reader input) {
    this.input = CharReader.get(input);
  }
  
  /** Construct a tokenizer with null input using the given AttributeFactory. */
  protected Tokenizer(AttributeFactory factory) {
    super(factory);
  }

  /** Construct a token stream processing the given input using the given AttributeFactory. */
  protected Tokenizer(AttributeFactory factory, Reader input) {
    super(factory);
    this.input = CharReader.get(input);
  }

  /** Construct a token stream processing the given input using the given AttributeSource. */
  protected Tokenizer(AttributeSource source) {
    super(source);
  }

  /** Construct a token stream processing the given input using the given AttributeSource. */
  protected Tokenizer(AttributeSource source, Reader input) {
    super(source);
    this.input = CharReader.get(input);
  }
  
  /** By default, closes the input Reader. */
  @Override
  public void close() throws IOException {
    if (input != null) {
      input.close();
      // LUCENE-2387: don't hold onto Reader after close, so
      // GC can reclaim
      input = null;
    }
  }
  
  /** Return the corrected offset. If {@link #input} is a {@link CharStream} subclass
   * this method calls {@link CharStream#correctOffset}, else returns <code>currentOff.
   * @param currentOff offset as seen in the output
   * @return corrected offset based on the input
   * @see CharStream#correctOffset
   */
  protected final int correctOffset(int currentOff) {
    return (input instanceof CharStream) ? ((CharStream) input).correctOffset(currentOff) : currentOff;
  }

  /** Expert: Reset the tokenizer to a new reader.  Typically, an
   *  analyzer (in its reusableTokenStream method) will use
   *  this to re-use a previously created tokenizer. */
  public void reset(Reader input) throws IOException {
    this.input = input;
  }
}