你的位置:首页 > Java教程

[Java教程]Lucene基础(三)


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

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