我会使用 a SpanFirstQuery
,它匹配字段开头附近的术语。作为所有跨度查询,它依赖于位置,在 lucene 中进行索引时默认启用。
让我们独立测试一下:您只需要提供您的SpanTermQuery
和可以找到该术语的最大位置(在我的示例中为一个)。
SpanTermQuery spanTermQuery = new SpanTermQuery(new Term("title", "lucene"));
SpanFirstQuery spanFirstQuery = new SpanFirstQuery(spanTermQuery, 1);
鉴于您的两个文档,如果您使用StandardAnalyzer
.
现在我们可以以某种方式将上述SpanFirstQuery
内容与普通文本查询结合起来,并让第一个只影响分数。您可以使用 a 轻松完成此操作BooleanQuery
,并将 span 查询作为 should 子句,如下所示:
Term term = new Term("title", "lucene");
TermQuery termQuery = new TermQuery(term);
SpanFirstQuery spanFirstQuery = new SpanFirstQuery(new SpanTermQuery(term), 1);
BooleanQuery booleanQuery = new BooleanQuery();
booleanQuery.add(new BooleanClause(termQuery, BooleanClause.Occur.MUST));
booleanQuery.add(new BooleanClause(spanFirstQuery, BooleanClause.Occur.SHOULD));
可能有不同的方法可以实现相同的目标,可能使用 a CustomScoreQuery
too 或自定义代码来实现评分,但在我看来,这似乎是最简单的一种。
我用来测试它的代码打印以下输出(包括分数),TermQuery
首先执行唯一的,然后是唯一的SpanFirstQuery
,最后是组合的BooleanQuery
:
------ TermQuery --------
Total hits: 2
title: I have a question about lucene - score: 0.26010898
title: Lucene: I have a really hard question about it - score: 0.22295055
------ SpanFirstQuery --------
Total hits: 1
title: Lucene: I have a really hard question about it - score: 0.15764984
------ BooleanQuery: TermQuery (MUST) + SpanFirstQuery (SHOULD) --------
Total hits: 2
title: Lucene: I have a really hard question about it - score: 0.26912516
title: I have a question about lucene - score: 0.09196242
这是完整的代码:
public static void main(String[] args) throws Exception {
Directory directory = FSDirectory.open(new File("data"));
index(directory);
IndexReader indexReader = DirectoryReader.open(directory);
IndexSearcher indexSearcher = new IndexSearcher(indexReader);
Term term = new Term("title", "lucene");
System.out.println("------ TermQuery --------");
TermQuery termQuery = new TermQuery(term);
search(indexSearcher, termQuery);
System.out.println("------ SpanFirstQuery --------");
SpanFirstQuery spanFirstQuery = new SpanFirstQuery(new SpanTermQuery(term), 1);
search(indexSearcher, spanFirstQuery);
System.out.println("------ BooleanQuery: TermQuery (MUST) + SpanFirstQuery (SHOULD) --------");
BooleanQuery booleanQuery = new BooleanQuery();
booleanQuery.add(new BooleanClause(termQuery, BooleanClause.Occur.MUST));
booleanQuery.add(new BooleanClause(spanFirstQuery, BooleanClause.Occur.SHOULD));
search(indexSearcher, booleanQuery);
}
private static void index(Directory directory) throws Exception {
IndexWriterConfig config = new IndexWriterConfig(Version.LUCENE_41, new StandardAnalyzer(Version.LUCENE_41));
IndexWriter writer = new IndexWriter(directory, config);
FieldType titleFieldType = new FieldType();
titleFieldType.setIndexOptions(FieldInfo.IndexOptions.DOCS_AND_FREQS_AND_POSITIONS);
titleFieldType.setIndexed(true);
titleFieldType.setStored(true);
Document document = new Document();
document.add(new Field("title","I have a question about lucene", titleFieldType));
writer.addDocument(document);
document = new Document();
document.add(new Field("title","Lucene: I have a really hard question about it", titleFieldType));
writer.addDocument(document);
writer.close();
}
private static void search(IndexSearcher indexSearcher, Query query) throws Exception {
TopDocs topDocs = indexSearcher.search(query, 10);
System.out.println("Total hits: " + topDocs.totalHits);
for (ScoreDoc hit : topDocs.scoreDocs) {
Document result = indexSearcher.doc(hit.doc);
for (IndexableField field : result) {
System.out.println(field.name() + ": " + field.stringValue() + " - score: " + hit.score);
}
}
}