Apache Lucene 评分原理及代码分析
在IndexSearcher类中有一个管理Lucene得分情况的方法，如下所示：1 public Explanation explain(Weight weight, int doc) throws IOException {
2 return weight.explain(reader, doc);
3 }
返回的这个Explanation的实例解释了Lucene中Document的得分情况。我们可以测试一下，直观地感觉一下到底这个Explanation的实例都记录了一个Document的哪些信息。
写一个测试类，如下所示：
1 package org.shirdrn.lucene.learn;
2
3 import java.io.IOException;
4 import java.util.Date;
5
6 import net.teamhot.lucene.ThesaurusAnalyzer;
7
8 import org.apache.lucene.document.Document;
9 import org.apache.lucene.document.Field;
10 import org.apache.lucene.index.CorruptIndexException;
11 import org.apache.lucene.index.IndexWriter;
12 import org.apache.lucene.index.Term;
13 import org.apache.lucene.index.TermDocs;
14 import org.apache.lucene.search.Explanation;
15 import org.apache.lucene.search.Hits;
16 import org.apache.lucene.search.IndexSearcher;
17 import org.apache.lucene.search.Query;
18 import org.apache.lucene.search.TermQuery;
19 import org.apache.lucene.store.LockObtainFailedException;
20
21 public class AboutLuceneScore {
22
23 private String path = "E:\\Lucene\\index";
24
25 public void createIndex(){
26 IndexWriter writer;
27 try {
28 writer = new IndexWriter(path,new ThesaurusAnalyzer(),true);
29
30 Field fieldA = new Field("contents","一人",Field.Store.YES,Field.Index.TOKENIZED);
31 Document docA = new Document();
32 docA.add(fieldA);
33
34 Field fieldB = new Field("contents","一人 之交 一人之交",Field.Store.YES,Field.Index.TOKENIZED);
35 Document docB = new Document();
36 docB.add(fieldB);
37
38 Field fieldC = new Field("contents","一人 之下 一人之下",Field.Store.YES,Field.Index.TOKENIZED);
39 Document docC = new Document();
40 docC.add(fieldC);
41
42 Field fieldD = new Field("contents","一人 做事 一人当 一人做事一人当",Field.Store.YES,Field.Index.TOKENIZED);
43 Document docD = new Document();
44 docD.add(fieldD);
45
46 Field fieldE = new Field("contents","一人 做事 一人當 一人做事一人當",Field.Store.YES,Field.Index.TOKENIZED);
47 Document docE = new Document();
48 docE.add(fieldE);
49
50 writer.addDocument(docA);
51 writer.addDocument(docB);
52 writer.addDocument(docC);
53 writer.addDocument(docD);
54 writer.addDocument(docE);
55
56 writer.close();
57 } catch (CorruptIndexException e) {
58 e.printStackTrace();
59 } catch (LockObtainFailedException e) {
60 e.printStackTrace();
61 } catch (IOException e) {
62 e.printStackTrace();
63 }
64 }
65
66 public static void main(String[] args) {
67 AboutLuceneScore aus = new AboutLuceneScore();
68 aus.createIndex(); // 建立索引
69 try {
70 String keyword = "一人";
71 Term term = new Term("contents",keyword);
72 Query query = new TermQuery(term);
73 IndexSearcher searcher = new IndexSearcher(aus.path);
74 Date startTime = new Date();
75 Hits hits = searcher.search(query);
76 TermDocs termDocs = searcher.getIndexReader().termDocs(term);
77 while(termDocs.next()){
78 System.out.print("搜索关键字在编号为 "+termDocs.doc());
79 System.out.println(" 的Document中出现过 "+termDocs.freq()+" 次");
80 }
81 System.out.println("********************************************************************");
82 for(int i=0;i
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