Lucene4.10使用教程(七)：Lucene的自定义评分

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自定义评分的第一种实现方式，详细内容可以查看代码注释

package com.johnny.lucene04.advance_search.selfScore;

import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;

import org.apache.lucene.document.Document;
import org.apache.lucene.index.AtomicReaderContext;
import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.queries.CustomScoreProvider;
import org.apache.lucene.queries.CustomScoreQuery;
import org.apache.lucene.search.FieldCache;
import org.apache.lucene.search.FieldCache.Longs;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.TermQuery;
import org.apache.lucene.search.TopDocs;

import com.johnny.lucene04.advance_search.FileIndexUtils;

/**
* 自定义评分第一种写法
* （1）创建类并继承CustomScoreQuery
   （2）覆盖重写类中的getCusomScoreProvider方法
   （3）创建类并继承CustomScoreProvider
   （4）覆盖重写类中的customScore确定新的评分规则
* @author Johnny
*
*/
public class MySelfScore {
   public void searchBySelfScore(){
       try{
           IndexSearcher search = new IndexSearcher(DirectoryReader.open(FileIndexUtils.getDirectory()));
           Query q = new TermQuery(new Term("content","java"));
           MyCustomScoreQuery myQuery = new MyCustomScoreQuery(q);
           TopDocs tds = search.search(myQuery, 200);

           SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

           for(ScoreDoc sd:tds.scoreDocs){
               Document d = search.doc(sd.doc);
               System.out.println(sd.doc+":("+sd.score+")" +
                       "["+d.get("filename")+"【"+d.get("path")+"】--->"+
                       d.get("size")+"-----"+sdf.format(new Date(Long.valueOf(d.get("date"))))+"]");

           }
           System.out.println("-----------Total result:"+tds.scoreDocs.length);
       }catch(Exception e){
           e.printStackTrace();
       }
   }
   /**
   *重写评分的实现方式
   * **/
   private class MyScoreProvider extends CustomScoreProvider{
       private AtomicReaderContext context;
       public MyScoreProvider(AtomicReaderContext context) {
           super(context);
           this.context = context;
       }
       /**重写评分方法，假定需求为文档size大于1000的评分/1000**/
       @Override
       public float customScore(int doc, float subQueryScore, float valSrcScore)
               throws IOException {
           // 从域缓存中加载索引字段信息
           Longs longs= FieldCache.DEFAULT.getLongs(context.reader(), "size", false);
           //doc实际上就是Lucene中得docId
           long size = longs.get(doc);
           float ff = 1f;//判断加权
           if(size>1000){
               ff = 1f/1000;
           }
           /*
             * 通过得分相乘放大分数
             * 此处可以控制与原有得分结合的方式，加减乘除都可以
             * **/
           return subQueryScore*valSrcScore*ff;
       }
   }
   /**
   * 重写CustomScoreQuery 的getCustomScoreProvider方法
   * 引用自定义的Provider
   */
   private class MyCustomScoreQuery extends CustomScoreQuery{

       public MyCustomScoreQuery(Query subQuery) {
           super(subQuery);
       }
       @Override
       protected CustomScoreProvider getCustomScoreProvider(
               AtomicReaderContext context) throws IOException {
           /**注册使用自定义的评分实现方式**/
           return new MyScoreProvider(context);
       }
   }
}

按照评分进行排序：

public class ScoreSearch {
   /**
   * 按照评分进行排序
   */
   public void searchByScore(String queryStr,Sort sort){
       try{
           IndexSearcher search = new IndexSearcher(DirectoryReader.open(FileIndexUtils.getDirectory()));
           QueryParser qp = new QueryParser("content", new StandardAnalyzer());
           Query q = qp.parse(queryStr);
           TopDocs tds = null;
           if(sort!=null){
               tds = search.search(q, 200,sort);
           }else{
               tds = search.search(q, 200);
           }
           for(ScoreDoc sd :tds.scoreDocs){
               Document d = search.doc(sd.doc);
               System.out.println(sd.doc+":("+sd.score+")" +
                       "["+d.get("filename")+"【"+d.get("path")+"】---"+d.get("score")+"--->"+
                       d.get("size")+"]");
           }
       }catch(Exception e){
           e.printStackTrace();
       }
   }

测试方法如下：

@Test
   public void testSearchByScore(){
       ScoreSearch ss = new ScoreSearch();
       /**sort没有set sort时，默认按照关联性进行排序**/
       Sort sort = new Sort();
       //sort.setSort(new SortField("score", Type.INT,true));//true表示倒叙，默认和false表示正序
       sort.setSort(new SortField("size", Type.LONG),new SortField("score",Type.INT));
       ss.searchByScore("java",sort);
   }

   @Test
   public void testSelfScore(){
       MySelfScore mss = new MySelfScore();
       /**
       * 如果使用标准分词器，那么java类中得java.io.IOException会被认为是一个词，不会进行拆分
       */
       mss.searchBySelfScore();
   }

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