Lucene在结果中索引
转自:http://blog.csdn.net/xyx139/article/details/6953510
测试实例:
package com.wsjava;
import java.io.IOException;
import org.apache.lucene.analysis.SimpleAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.queryParser.ParseException;
import org.apache.lucene.queryParser.QueryParser;
import org.apache.lucene.search.CachingWrapperFilter;
import org.apache.lucene.search.Filter;
import org.apache.lucene.search.Hits;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.QueryFilter;
public class IndexTest {
public static void main(String[] args) throws IOException, ParseException {
index();
search("day"); //简单搜索
searchInResult("day", "you"); //在结果集中搜索
}
public static void index() throws IOException {
IndexWriter writer = new IndexWriter("d:/tesindex",new SimpleAnalyzer(), true);
writer.setMaxMergeDocs(1000);
writer.setMergeFactor(100);
for (int i = 0; i < 10; i++) {
Document doc = new Document();
String content = "How do you do?";
if (i >= 5) {
content = "What's a good day. ";
}
if (i >= 7) {
content = "Nice day. Thanks you!";
}
doc.add(new Field("content", content, Field.Store.YES,Field.Index.TOKENIZED));
writer.addDocument(doc);
}
}
//简单实现对qw的搜索.
public static void search(String qw) throws IOException, ParseException {
QueryParser queryParser = new QueryParser("content",new SimpleAnalyzer());
Query query = queryParser.parse(qw.trim());
QueryFilter filter = new QueryFilter(query);
search(query, filter);
}
//在搜索oldqw的结果集中搜索qw.
public static void searchInResult(String qw, String oldqw) throws ParseException, IOException {
QueryParser queryParser = new QueryParser("content",new SimpleAnalyzer());
Query query = queryParser.parse(qw.trim());
Query oldQuery = queryParser.parse(oldqw.trim());
QueryFilter oldFilter = new QueryFilter(oldQuery);
CachingWrapperFilter filter = new CachingWrapperFilter(oldFilter);
search(query, filter);
}
private static void search(Query query, Filter filter) throws IOException, ParseException {
IndexSearcher ins = new IndexSearcher("d:/tesindex");
Hits hits = ins.search(query, filter);
for (int i = 0; i < hits.length(); i++) {
Document doc = hits.doc(i);
System.out.println(doc.get("content"));
}
System.out.println();
}
}
Lucene.net的搜索结果的百分比相关度值是如何实现的?
答:
Hits result = searcher.Search(q);
float score = result.Score(n) ;//n为查询结果文挡序号,返回的是一个<=1f的float的值,表示为百分比字符串:score.ToString("0%") ;
问:如何通过编程的方式改变Lucene.net的锁文件存放的位置?
答:
Lucene.net的锁文件默认是存放系统临时文件夹,可以通过下面的语句来修改
System.Configuration.ConfigurationSettings.AppSettings.Add("Lucene.Net.lockDir", "your new lockDir") ;
通过FSDirectory.LOCK_DIR可以获得锁文件存放的位置(文件夹)
问:如何判断某个索引库被锁定,如何强制解除锁定?
答:
具体实现,可以参看Lucene.Net.Store.FSDirectory的Obtain()(判断是否锁定)方法和Release()方法(解除锁定)
备注:还有一个IsLocked方法也可以参考下。
问:如何实现多个索引的联合搜索?
答:
IndexSearcher[] searchers = new IndexSearcher[2];
searchers[0] = new IndexSearcher(dir1) ;
searchers[1] = new IndexSearcher(dir2) ;
MultiSearcher searcher = new MultiSearcher(searchers) ;//或ParallelMultiSearcher searcher = new ParallelMultiSearcher(searchers) ;
searcher.Search(query) ;
ParallelMultiSearcher与MultiSearcher的区别,前者为每一个索引单独开一个线程,以多线程的方式同步搜索;后者是逐个依次搜索,然后合并;
所以ParallelMultiSearcher的搜索总用时是最慢的哪个索引的搜索用时,MultiSearcher则是搜索总用时等于所有索引搜索用时之和;
问:如何实现在结果中搜索?
答:
*方法一,使用CachingWrapperFilter。不能实现无限级的“在结果中搜索”:
QueryParser parser = new QueryParser("content", analyzer);
Query currentQuery = parser.Parse(currentKeyword) ;
Query oldQuery = parser.Parse(oldKeyword) ;
QueryFilter oldFilter = new QueryFilter(oldQuery) ;
CachingWrapperFilter filter = new CachingWrapperFilter(oldFilter) ;
IndexSearcher searcher = new IndexSearcher(indexDir);
Hits result = searcher.Search(currentQuery, filter) ;
*方法二,将多个查询关键词做AND的BooleanQuery或者直接构造查询Sytax传给QueryParser,都可以实现无限级的“在结果中搜索“。
问:BooleanQuery.maxClauseCount的含义?
答:
添加到BooleanQuery的最多的Query数,默认是1024。超过该值会抛出TooManyClauses异常,可以通过BooleanQuery.SetMaxClauseCount(int)设置新的值。
备注:含义解释未明确。
问:如何判断一个索引库是否存在?
答:
string indexPath = "your indexPath" ; //索引所在目录
if (System.IO.Directory.Exists(indexPath) && System.IO.File.Exists(Path.Combine(indexPath,"segments")
//存在
else
//不存在
当然有更直接的方法
if (Lucene.Net.Index.IndexReader.IndexExists(indexPath))
//存在
else
//不存在
Lucene.Net.Index.IndexReader.IndexExists方法内部的实现方式和上面的类似,当然直接用Lucene.Net.Index.IndexReader.IndexExists更可靠些。
Lucene.net索引合并
Lucene.Net.Store.Directory directory1 = FSDirectory.GetDirectory("e:\\Index1", false);
Lucene.Net.Store.Directory directory2 = FSDirectory.GetDirectory("e:\\Index2", false);
IndexWriter writer = new IndexWriter(directory1, new ChineseAnalyzer(), false);
writer.AddIndexes(new Lucene.Net.Store.Directory[] { directory2 });
Console.WriteLine("正在合并索引"+writer.DocCount().ToString());
writer.Close();