lucene-SpanQuery跨度查询基础

1、跨度查询SpanQuery5个子类

SpanQuery类型 描述

SpanTermQuery 和其他跨度查询结合使用，单独使用相当于TermQuery

SpanFirstQuery 用来匹配域中的第一个部分内的各个spans

SpanNearQuery 用来匹配临近的spans

SpanNotQuery 用来匹配不重叠的spans

SpanOrQuery span查询的聚合匹配

2、测试SpanQuery

public class SpanQueryTest extends TestCase{

private RAMDirectory directory;

private IndexSearcher searcher;

private IndexReader reader;

private SpanTermQuery quick;

private SpanTermQuery brown;

private SpanTermQuery red;

private SpanTermQuery fox;

private SpanTermQuery lazy;

private SpanTermQuery Sleepy;

private SpanTermQuery dog;

private SpanTermQuery cat;

private Analyzer analyzer;

protected void setUp() throws Exception{

directory=new RAMDirectory();

analyzer=new WhitespaceAnalyzer();

IndexWriter writer=new IndexWriter(directory,analyzer,true);

Document doc=new Document();

doc.add(Field.Text("f","the quck brown fox jumps over the lazy dog"));

writer.addDocument(doc);

doc=new Document();

doc.add(Field.Text("f","the quick red fox jumps over the sleepy cat"));

writer.addDocument(doc);

writer.close();

searcher=nwe IndexSearcher(directory);

reader=IndexReader.open(directory);

quick=new SpanTermQuery(new Term("f","quick"));

brown=new SpanTermQuery(new Term("f","brown"));

red=new SpanTermQuery(new Term("f","red"));

fox=new SpanTermQuery(new Term("f","fox"));

lazy=new SpanTermQuery(new Term("f","lazy"));

sleepy=new SpanTermQuery(new Term("f","dog"));

dog=new SpanTermQuery(new Term("f","cat"));

}

private
void assertOnlyBrownFox(Query query) throws
Exception{//检查是否返回一个匹配结果

Hits hits=searcher.search(query);

assertEquals(1,hits.length());

assertEquals("wrong doc",0,hits.id(0));

}

private
void assertBothFoxes(Query query) throws
Exception{//检查是否返回2个匹配结果

Hits hits=searcher.search(query);

assertEquals(2.hits.length());

}

private
void assertNotMatch(Query query) throws Exception{

Hits hits=searcher.search(query);

assertEquals(0,hits.length());

}

}

3、使用SpanTermQuery类，它匹配文档的方式与TermQuery相似，但是它会记录一个文档中的相同项在文档中出现的不同位置。

　　　SpanQuery对象一直跟踪它所匹配的结果：对于每个正进行匹配的文档，它记录下被匹配的查询文本的所有起点和终点位置（以语汇单元为一个位置）。

dumpSpans(new SpanTermQuery(new
Term("f","the")));//查询文本为the，带the的所有文档，并显示查询细节

定义一个方法dumpSpans()调用SpanQuery的一些底层API为我们查询细节。

public void dumpSpans(SpanQuery query) throws IOException{

Spans
spans=query.getSpans(reader);

System.out.println(query+":");

int
numSpans=0;

Hits
hits=searcher.search(query);

Float[]
scores=new float[2];

for (int
i0;i<hits.length();i++){

scores[hits.id(i)]=hits.score(i);

}

while
(spans.next()){//spans里是单个查询文本匹配情况情况，记录着query在文档中的位置，

//next表示query在文档中的下一个位置，以及查询文本所在的文档号

numSpans++;

int id=spans.doc();

Document doc=reader.document(id);

Token[]
tokens=AnaylzerUtilts.tokensFromAnalysis(analyzer,doc.get("f"));

StringBuffer buffer=new StringBuffer();

buffer.append(" ");

for (int i=0;i<tokens.length;i++){

if (i==spans.start()){

buffer.append("<");

}

buffer.append(tokens[i].termText());

if (i+1==spans.end()){

buffer.append(">");

}

buffer.append(" ");

}

buffer.append("("+scores[id]+")");

System.out.println(buffer);//输出spans的查询文本的在文档中本次出现的信息。

}

if
(numspans==0){

System.out.println("
no spans");//没有任何匹配

}

System.out.println();

}

第1次spans.next循环所输出:<the> quick
brown fox jumps over the lazy dog(0.18123456)

第2次spans.next循环所输出:the quick brown fox jumps over
<the> lazy dog(0.18123456)

第3次spans.next循环所输出:<the> quick red
fox jumps over the sleep dog(0.18123456)

第4次spans.next循环所输出:the quick red fox jumps over
<the> sleep
dog(0.18123456)