cwordfilter.java

「我是中國人」

package org.apache.lucene.analysis.cw;
import org.apache.lucene.analysis.Token;
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import java.io.*;
import java.util.*;
import java.util.logging.*;
import org.apache.lucene.analysis.*;

/**
 * Title: CWordFilter
 * Description: Filter with a stop word table
 *              Rule: No digital is allowed.
 *                    English word/token should larger than 1 character.
 *                    One Chinese character as one Chinese word.
 * TO DO:
 *   1. Add Chinese stop words, such as \ue400
 *   2. Dictionary based Chinese word extraction
 *   3. Intelligent Chinese word extraction
 *
 * Copyright:    Copyright (c) 2005
 * Company:
 * @author siuying
 * @version 1.0
 *
 */

public final class CWordFilter extends TokenFilter {
    private static Logger logger = Logger.getLogger(CWordFilter.class.getName());
    
    public static final String[] STOP_WORDS = {
    "and", "are", "as", "at", "be", "but", "by",
    "for", "if", "in", "into", "is", "it",
    "no", "not", "of", "on", "or", "such",
    "that", "the", "their", "then", "there", "these",
    "they", "this", "to", "was", "will", "with", "www"
    };


    private Set stopword;
    private TokenStream filteredStream;
    
    public CWordFilter(TokenStream in) {
        super(in);
        
        /* english stop words */
        stopword = new TreeSet();
        for (int i = 0; i < STOP_WORDS.length; i++){
            stopword.add(STOP_WORDS[i]);
        }
        
        /* chinese stop words */
        try{
            segmenter mainsegmenter = SegmenterUtils.getSegmenter("zword.obj");
            stopword.addAll(mainsegmenter.getCnotname());
        }catch(Exception ioe){
            logger.warning("Failed loading segmenter!");
        }
        
        logger.fine("Stop Word: " + stopword);
        filteredStream = new StopFilter(in, stopword);
    }

    public final Token next() throws java.io.IOException {
        Token tk = filteredStream.next();
        if (tk != null) logger.finest( tk.termText() );
        return tk;
    }

}