ik-analyzer-solr/src/main/java/org/wltea/analyzer/lucene/IKTokenizer.java

/*
 * IK 中文分词  版本 8.4.0
 * IK Analyzer release 8.4.0
 *
 * 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.
 *
 * 源代码由林良益(linliangyi2005@gmail.com)提供
 * 版权声明 2012，乌龙茶工作室
 * provided by Linliangyi and copyright 2012 by Oolong studio
 *
 * 8.4.0版本 由 Magese (magese@live.cn) 更新
 * release 8.4.0 update by Magese(magese@live.cn)
 *
 */
package org.wltea.analyzer.lucene;

import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.tokenattributes.OffsetAttribute;
import org.apache.lucene.analysis.tokenattributes.TypeAttribute;
import org.apache.lucene.util.AttributeFactory;
import org.wltea.analyzer.core.IKSegmenter;
import org.wltea.analyzer.core.Lexeme;

import java.io.IOException;

/**
 * IK分词器 Lucene Tokenizer适配器类
 * 兼容Lucene 4.0版本
 */
@SuppressWarnings("unused")
public final class IKTokenizer extends Tokenizer {

    //IK分词器实现
    private IKSegmenter _IKImplement;

    //词元文本属性
    private CharTermAttribute termAtt;
    //词元位移属性
    private OffsetAttribute offsetAtt;
    //词元分类属性（该属性分类参考org.wltea.analyzer.core.Lexeme中的分类常量）
    private TypeAttribute typeAtt;
    //记录最后一个词元的结束位置
    private int endPosition;

    /**
     * Lucene 7.6 Tokenizer适配器类构造函数
     */
    public IKTokenizer() {
        this(false);
    }

    IKTokenizer(boolean useSmart) {
        super();
        init(useSmart);
    }

    public IKTokenizer(AttributeFactory factory) {
        this(factory, false);
    }

    IKTokenizer(AttributeFactory factory, boolean useSmart) {
        super(factory);
        init(useSmart);
    }

    private void init(boolean useSmart) {
        offsetAtt = addAttribute(OffsetAttribute.class);
        termAtt = addAttribute(CharTermAttribute.class);
        typeAtt = addAttribute(TypeAttribute.class);
        _IKImplement = new IKSegmenter(input, useSmart);
    }

    /* (non-Javadoc)
     * @see org.apache.lucene.analysis.TokenStream#incrementToken()
     */
    @Override
    public boolean incrementToken() throws IOException {
        //清除所有的词元属性
        clearAttributes();
        Lexeme nextLexeme = _IKImplement.next();
        if (nextLexeme != null) {
            //将Lexeme转成Attributes
            //设置词元文本
            termAtt.append(nextLexeme.getLexemeText());
            //设置词元长度
            termAtt.setLength(nextLexeme.getLength());
            //设置词元位移
            offsetAtt.setOffset(nextLexeme.getBeginPosition(), nextLexeme.getEndPosition());
            //记录分词的最后位置
            endPosition = nextLexeme.getEndPosition();
            //记录词元分类
            typeAtt.setType(nextLexeme.getLexemeTypeString());
            //返会true告知还有下个词元
            return true;
        }
        //返会false告知词元输出完毕
        return false;
    }

    /*
     * (non-Javadoc)
     * @see org.apache.lucene.analysis.Tokenizer#reset(java.io.Reader)
     */
    @Override
    public void reset() throws IOException {
        super.reset();
        _IKImplement.reset(input);
    }

    @Override
    public final void end() {
        // set final offset
        int finalOffset = correctOffset(this.endPosition);
        offsetAtt.setOffset(finalOffset, finalOffset);
    }
}