lucene3.0_IndexSearcher的基础施用及注意事项

lucene3.0_IndexSearcher的基础使用及注意事项
?voidsearch(Query?query,?Collector?results)?
??????????Lower-level search API.?voidsearch(Query?query,?Filter?filter,?Collector?results)?
??????????Lower-level search API.?TopDocssearch(Query?query,?Filter?filter, int?n)?
??????????Finds the top?n?hits for?query, applying?filter?if non-null.?TopFieldDocssearch(Query?query,?Filter?filter, int?n,?Sort?sort)?
??????????Search implementation with arbitrary sorting.?TopDocssearch(Query?query, int?n)?
??????????Finds the top?n?hits for?query.abstract ?voidsearch(Weight?weight,?Filter?filter,?Collector?results)?
??????????Lower-level search API.abstract ?TopDocssearch(Weight?weight,?Filter?filter, int?n)?
??????????Expert: Low-level search implementation.abstract ?TopFieldDocssearch(Weight?weight,?Filter?filter, int?n,?Sort?sort)?
??????????Expert: Low-level search implementation with arbitrary sorting.

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该文将讲解上表格中黄色高亮的3个方法：

1.search(Query query , int n)

2.search(Query query , Collector results)

3.search(Query query , Filter filter , int n , Sort sort)

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1.search(Query query , int n)示例

取出前n条目标结果。

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publicvoid?searcher(String queryString){
try?{
FSDirectory dir?=?SimpleFSDirectory.open(new?File("d:/20101015index"));
//注意点1:创建IndexSearcher实例是传入IndexReader实例还是Directory实例呢？
IndexReader reader?=?IndexReader.open(dir);
IndexSearcher searcher?=new?IndexSearcher(reader);
//使用：search(Query query, int n)?
QueryParser parser?=new?QueryParser(Version.LUCENE_30,?"f1",?new?StandardAnalyzer(Version.LUCENE_30));
Query query?=?parser.parse(queryString);
TopDocs tds?=?searcher.search(query,?5);
ScoreDoc[] sd?=?tds.scoreDocs;
for?(int?i?=0; i?<?sd.length; i++) {
System.out.println(reader.document(sd[i].doc));
//注意点2：怎么查看每个文档的打分的详情。
//explain(Weight weight, int doc)?
//Expert: low-level implementation method Returns an Explanation that describes how doc scored against weight.
System.out.println("Explanation:"+?(searcher.explain(query, sd[i].doc)));
}
}?catch?(IOException e) {
e.printStackTrace();
}?catch?(ParseException e) {
e.printStackTrace();
}?
}

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注意点：

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1.创建IndexSearcher实例是传入IndexReader实例还是Directory实例呢？

详情请参见:

lucene问题_IndexSearcher初始化，IndexSearcher(Directory dir)和IndexSearcher(IndexReader reader)有什么区别？到底使用那个更合理？

2.查看每个目标文档的打分的详细情况。

在网上看到有朋友问到这个，故在此提出来。

3.真实的项目请不要像上面代码那样——将indexReader和IndexSearcher的实例在搜索方法中创建，为了节约系统开销、提高效率，

应该将这些实例作为单例模式。

这里做了反面教材了 = =！

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2.search(Query query , Collector results)

在介绍这个方法之前，先来了解下Collector：

?Collectors are primarily meant to be used to gather raw results from a search, and implement sorting or custom result filtering, collation, etc.

先重点了解：

TopScoreDocCollector?is a concrete subclass?TopDocsCollector?and sorts according to score + docID.?

This is used internally by the?IndexSearcher?search methods that do not take an explicitSort. It is likely the most frequently used collector.

他是最常用的collector子类，是默认相关度排序的。下面给出一个实例，使用TopScoreDocCollector进行结果的收集，并提供简单的分页功能。

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publicvoid?searcher(String queryString ,int?start,?int?howMany){
try?{
FSDirectory dir?=?SimpleFSDirectory.open(new?File("d:/20101015index"));
//注意点1:创建IndexSearcher实例是传入IndexReader实例还是Directory实例呢？
IndexReader reader?=?IndexReader.open(dir);
IndexSearcher searcher?=new?IndexSearcher(reader);
//使用：search(Query query , Collector results)
QueryParser parser?=new?QueryParser(Version.LUCENE_30,?"f1",?new?StandardAnalyzer(Version.LUCENE_30));
Query query?=?parser.parse(queryString);
int?hm?=?start+howMany ;
TopScoreDocCollector res?= TopScoreDocCollector.create(hm, false);
System.out.println("total hits :"+res.getTotalHits());
searcher.search(query, res);
//注意点2:这里可以控制分页。
TopDocs tds =?res.topDocs(start, howMany);
ScoreDoc[] sd?=?tds.scoreDocs;
for?(int?i?=0; i?<?sd.length; i++) {
System.out.println(reader.document(sd[i].doc));
//?System.out.println("Explanation:" + (searcher.explain(query, sd[i].doc)));
}
}?catch?(IOException e) {
e.printStackTrace();
}?catch?(ParseException e) {
e.printStackTrace();
}?
}

?

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3.search(Query query , Filter filter , int n , Sort sort)

这种方式的排序很简单，直接给出实例代码，注意的问题其他文章有详细说明。

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按 Ctrl+C 复制代码按 Ctrl+C 复制代码

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注意点：

lucene问题_检索结果怎么排序？对于不同类型（例如int型）的字段排序有什么区别吗？

lucene问题_怎么对多个字段进行排序？

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对于lucene3.0检索的基础使用就先介绍这些了，关于搜索应该重点关注：

1.collector的选用

2.分页，及分页效率问题

3.排序，及排序的效率问题

4.多索引搜索

5.实际项目中实时搜索和效率的保障

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??分类:?92-搜索引擎_lucene

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