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Lucene example source code file (KeywordMarkerFilter.java)

This example Lucene source code file (KeywordMarkerFilter.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

chararrayset, chararrayset, chartermattribute, io, ioexception, ioexception, keywordattribute, keywordmarkerfilter, keywordmarkerfilter, override, set, tokenfilter, tokenstream, tokenstream, util

The Lucene KeywordMarkerFilter.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.util.Set;

import org.apache.lucene.analysis.tokenattributes.KeywordAttribute;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.util.Version;

/**
 * Marks terms as keywords via the {@link KeywordAttribute}. Each token
 * contained in the provided is marked as a keyword by setting
 * {@link KeywordAttribute#setKeyword(boolean)} to <code>true.
 * 
 * @see KeywordAttribute
 */
public final class KeywordMarkerFilter extends TokenFilter {

  private final KeywordAttribute keywordAttr = addAttribute(KeywordAttribute.class);
  private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
  private final CharArraySet keywordSet;

  /**
   * Create a new KeywordMarkerFilter, that marks the current token as a
   * keyword if the tokens term buffer is contained in the given set via the
   * {@link KeywordAttribute}.
   * 
   * @param in
   *          TokenStream to filter
   * @param keywordSet
   *          the keywords set to lookup the current termbuffer
   */
  public KeywordMarkerFilter(final TokenStream in,
      final CharArraySet keywordSet) {
    super(in);
    this.keywordSet = keywordSet;
  }

  /**
   * Create a new KeywordMarkerFilter, that marks the current token as a
   * keyword if the tokens term buffer is contained in the given set via the
   * {@link KeywordAttribute}.
   * 
   * @param in
   *          TokenStream to filter
   * @param keywordSet
   *          the keywords set to lookup the current termbuffer
   */
  public KeywordMarkerFilter(final TokenStream in, final Set<?> keywordSet) {
    this(in, keywordSet instanceof CharArraySet ? (CharArraySet) keywordSet
        : CharArraySet.copy(Version.LUCENE_31, keywordSet));
  }

  @Override
  public final boolean incrementToken() throws IOException {
    if (input.incrementToken()) {
      if (keywordSet.contains(termAtt.buffer(), 0, termAtt.length())) { 
        keywordAttr.setKeyword(true);
      }
      return true;
    } else {
      return false;
    }
  }
}

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