Lucene基础（三）-- 中文分词及高亮显示

Lucene分词器及高亮

分词器

在lucene中我们按照分词方式把文档进行索引，不同的分词器索引的效果不太一样，之前的例子使用的都是标准分词器，对于英文的效果很好，但是中文分词效果就不怎么样，他会按照汉字的字直接分词，没有词语的概念。

使用分词的地方只需要把Analyzer实例化成我们第三方的分词器即可

中文分词有很多，这里使用IKAnalyzer 为例，

下载地址 https://git.oschina.net/wltea/IK-Analyzer-2012FF 现在下来后里面有一篇教程。

高亮

导入lucene-highlighter-xxx.jar 在对查询出来的结果实现高亮显示

// 关键字高亮显示的html标签，需要导入lucene-highlighter-xxx.jar
SimpleHTMLFormatter simpleHTMLFormatter = new SimpleHTMLFormatter("<span style='color:red'>", "</span>");
Highlighter highlighter = new Highlighter(simpleHTMLFormatter, new QueryScorer(query));

for (int i = 0; i < hits.length; i++) {
Document doc = isearcher.doc(hits[i].doc);
// 内容增加高亮显示
TokenStream tokenStream = analyzer.tokenStream("content", new StringReader(doc.get("content")));
String content = highlighter.getBestFragment(tokenStream, doc.get("content"));
System.out.println(content);
}

Lucene中文分词器

实例：

package lucene_demo04;

import java.io.IOException;
import java.io.StringReader;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.document.TextField;
import org.apache.lucene.index.CorruptIndexException;
import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.IndexWriterConfig.OpenMode;
import org.apache.lucene.queryparser.classic.ParseException;
import org.apache.lucene.queryparser.classic.QueryParser;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.QueryWrapperFilter;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.highlight.Highlighter;
import org.apache.lucene.search.highlight.InvalidTokenOffsetsException;
import org.apache.lucene.search.highlight.QueryScorer;
import org.apache.lucene.search.highlight.SimpleHTMLFormatter;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.RAMDirectory;
import org.apache.lucene.util.Version;
import org.wltea.analyzer.lucene.IKAnalyzer;

/**
*中文分词，IKAnalayzer,对索引结果实现高亮显示
* @author YipFun
*/
public class LuceneDemo04 {
private static final Version version = Version.LUCENE_4_9;
private Directory directory = null;
private DirectoryReader ireader = null;
private IndexWriter iwriter = null;
private IKAnalyzer analyzer;

//测试数据
private String[] content = {
"你好，我是中共人",
"中华人民共和国",
"中国人民从此站起来了",
"Lucene是一个不错的全文检索的工具",
"全文检索中文分词"
};

/**
* 构造方法
*/
public LuceneDemo04() {
directory = new RAMDirectory();
}

private IKAnalyzer getAnalyzer(){
if(analyzer == null){
return new IKAnalyzer();
}else{
return analyzer;
}
}

/**
* 创建索引
*/
public void createIndex(){
Document doc = null;
try {
IndexWriterConfig iwConfig =  new IndexWriterConfig(version, getAnalyzer());
iwConfig.setOpenMode(OpenMode.CREATE_OR_APPEND);
iwriter = new IndexWriter(directory,iwConfig);
for(String text : content){
doc = new Document();
doc.add(new TextField("content", text,Field.Store.YES));
iwriter.addDocument(doc);
}

} catch (IOException e) {
e.printStackTrace();
}finally{
try {
if(iwriter != null)
iwriter.close();
} catch (IOException e) {
e.printStackTrace();
}
}

}

public IndexSearcher getSearcher(){
try {
if(ireader==null) {
ireader = DirectoryReader.open(directory);
} else {
DirectoryReader tr = DirectoryReader.openIfChanged(ireader) ;
if(tr!=null) {
ireader.close();
ireader = tr;
}
}
return new IndexSearcher(ireader);
} catch (CorruptIndexException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}

public void searchByTerm(String field,String keyword,int num) throws InvalidTokenOffsetsException{
IndexSearcher isearcher = getSearcher();
Analyzer analyzer =  getAnalyzer();
//使用QueryParser查询分析器构造Query对象
QueryParser qp = new QueryParser(version,
field,analyzer);
//这句所起效果？
qp.setDefaultOperator(QueryParser.OR_OPERATOR);
try {
Query query = qp.parse(keyword);
ScoreDoc[] hits;

//注意searcher的几个方法
hits = isearcher.search(query, null, num).scoreDocs;

// 关键字高亮显示的html标签，需要导入lucene-highlighter-xxx.jar
SimpleHTMLFormatter simpleHTMLFormatter = new SimpleHTMLFormatter("<span style='color:red'>", "</span>");
Highlighter highlighter = new Highlighter(simpleHTMLFormatter, new QueryScorer(query));

for (int i = 0; i < hits.length; i++) {
Document doc = isearcher.doc(hits[i].doc);
// 内容增加高亮显示
TokenStream tokenStream = analyzer.tokenStream("content", new StringReader(doc.get("content")));
String content = highlighter.getBestFragment(tokenStream, doc.get("content"));
System.out.println(content);
}

} catch (IOException e) {
e.printStackTrace();
} catch (ParseException e) {
e.printStackTrace();
}
}

/**
* 使用过滤器查询
* @param field
* @param keyword
* @param num
* @throws InvalidTokenOffsetsException
*/
public void searchByTermFilter(String field,String keyword,int num) throws InvalidTokenOffsetsException{
IndexSearcher isearcher = getSearcher();
Analyzer analyzer =  getAnalyzer();
//使用QueryParser查询分析器构造Query对象
QueryParser qp = new QueryParser(version,
field,analyzer);
//这句所起效果？
qp.setDefaultOperator(QueryParser.OR_OPERATOR);
try {
Query query = qp.parse(keyword);
Query q2 = qp.parse("全文检索");
ScoreDoc[] hits;

QueryWrapperFilter  filter=new QueryWrapperFilter(q2);
//注意searcher的几个方法
hits = isearcher.search(query, filter, num).scoreDocs;

// 关键字高亮显示的html标签，需要导入lucene-highlighter-xxx.jar
SimpleHTMLFormatter simpleHTMLFormatter = new SimpleHTMLFormatter("<span style='color:red'>", "</span>");
Highlighter highlighter = new Highlighter(simpleHTMLFormatter, new QueryScorer(query));

for (int i = 0; i < hits.length; i++) {
Document doc = isearcher.doc(hits[i].doc);
// 内容增加高亮显示
TokenStream tokenStream = analyzer.tokenStream("content", new StringReader(doc.get("content")));
String content = highlighter.getBestFragment(tokenStream, doc.get("content"));
System.out.println(content);
}

} catch (IOException e) {
e.printStackTrace();
} catch (ParseException e) {
e.printStackTrace();
}
}

public static void main(String[] args) throws InvalidTokenOffsetsException {
System.out.println("start");
LuceneDemo04 ld = new LuceneDemo04();
ld.createIndex();
long start = System.currentTimeMillis();
ld.searchByTerm("content","人民",500);
System.out.println("end search use "+(System.currentTimeMillis()-start)+"ms");
}

}

运行结果：

start
加载扩展词典：ext.dic
加载扩展停止词典：stopword.dic
中华<span style='color:red'>人民</span>共和国
中国<span style='color:red'>人民</span>从此站起来了
end search use 129ms