/**
* IK 中文分词 版本 5.0
* IK Analyzer release 5.0
*
* 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
*
*/
package org.wltea.analyzer.query;
import java.io.IOException;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.List;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.queryparser.classic.ParseException;
import org.apache.lucene.queryparser.classic.QueryParser;
import org.apache.lucene.search.Query;
import org.apache.lucene.util.Version;
import org.wltea.analyzer.core.IKSegmenter;
import org.wltea.analyzer.core.Lexeme;
/**
* Single Word Multi Char Query Builder
* IK分词算法专用
* @author linliangyi
*
*/
public class SWMCQueryBuilder {
/**
* 生成SWMCQuery
* @param fieldName
* @param keywords
* @param quickMode
* @return Lucene Query
*/
public static Query create(String fieldName ,String keywords , boolean quickMode){
if(fieldName == null || keywords == null){
throw new IllegalArgumentException("参数 fieldName 、 keywords 不能为null.");
}
//1.对keywords进行分词处理
List<Lexeme> lexemes = doAnalyze(keywords);
//2.根据分词结果，生成SWMCQuery
Query _SWMCQuery = getSWMCQuery(fieldName , lexemes , quickMode);
return _SWMCQuery;
}
/**
* 分词切分，并返回结链表
* @param keywords
* @return
*/
private static List<Lexeme> doAnalyze(String keywords){
List<Lexeme> lexemes = new ArrayList<Lexeme>();
IKSegmenter ikSeg = new IKSegmenter(new StringReader(keywords));
try{
Lexeme l = null;
while( (l = ikSeg.next()) != null){
lexemes.add(l);
}
}catch(IOException e){
e.printStackTrace();
}
return lexemes;
}
/**
* 根据分词结果生成SWMC搜索
* @param fieldName
// * @param pathOption
* @param quickMode
* @return
*/
private static Query getSWMCQuery(String fieldName , List<Lexeme> lexemes , boolean quickMode){
//构造SWMC的查询表达式
StringBuffer keywordBuffer = new StringBuffer();
//精简的SWMC的查询表达式
StringBuffer keywordBuffer_Short = new StringBuffer();
//记录最后词元长度
int lastLexemeLength = 0;
//记录最后词元结束位置
int lastLexemeEnd = -1;
int shortCount = 0;
int totalCount = 0;
for(Lexeme l : lexemes){
totalCount += l.getLength();
//精简表达式
if(l.getLength() > 1){
keywordBuffer_Short.append(' ').append(l.getLexemeText());
shortCount += l.getLength();
}
if(lastLexemeLength == 0){
keywordBuffer.append(l.getLexemeText());
}else if(lastLexemeLength == 1 && l.getLength() == 1
&& lastLexemeEnd == l.getBeginPosition()){//单字位置相邻，长度为一，合并)
keywordBuffer.append(l.getLexemeText());
}else{
keywordBuffer.append(' ').append(l.getLexemeText());
}
lastLexemeLength = l.getLength();
lastLexemeEnd = l.getEndPosition();
}
//借助lucene queryparser 生成SWMC Query
QueryParser qp = new QueryParser(Version.LUCENE_40, fieldName, new StandardAnalyzer(Version.LUCENE_40));
qp.setDefaultOperator(QueryParser.AND_OPERATOR);
qp.setAutoGeneratePhraseQueries(true);
if(quickMode && (shortCount * 1.0f / totalCount) > 0.5f){
try {
//System.out.println(keywordBuffer.toString());
Query q = qp.parse(keywordBuffer_Short.toString());
return q;
} catch (ParseException e) {
e.printStackTrace();
}
}else{
if(keywordBuffer.length() > 0){
try {
//System.out.println(keywordBuffer.toString());
Query q = qp.parse(keywordBuffer.toString());
return q;
} catch (ParseException e) {
e.printStackTrace();
}
}
}
return null;
}
}