PrefixQuery

PrefixQuery用于匹配索引以指定字符串开头的文档。

Class 声明 (Class Declaration)

以下是org.apache.lucene.search.PrefixQuery类的声明 -

public class PrefixQuery
   extends MultiTermQuery

类构造函数 (Class Constructors)

下表显示了不同的类构造函数 -

Class Methods

下表显示了不同的类方法 -

方法继承 (Methods Inherited)

该类继承以下类中的方法 -

• org.apache.lucene.search.MultiTermQuery
• org.apache.lucene.search.Query
• java.lang.Object

用法 (Usage)

private void searchUsingPrefixQuery(String searchQuery)
   throws IOException, ParseException {
   searcher = new Searcher(indexDir);
   long startTime = System.currentTimeMillis();
   //create a term to search file name
   Term term = new Term(LuceneConstants.FILE_NAME, searchQuery);
   //create the term query object
   Query query = new PrefixQuery(term);
   //do the search
   TopDocs hits = searcher.search(query);
   long endTime = System.currentTimeMillis();
   System.out.println(hits.totalHits +
      " documents found. Time :" + (endTime - startTime) + "ms");
   for(ScoreDoc scoreDoc : hits.scoreDocs) {
      Document doc = searcher.getDocument(scoreDoc);
      System.out.println("File: "+ doc.get(LuceneConstants.FILE_PATH));
   }
   searcher.close();
}

例子 Example Application

让我们创建一个测试Lucene应用程序来使用PrefixQuery测试搜索。

LuceneConstants.java

此类用于提供跨示例应用程序使用的各种常量。

package cn.xnip.lucene;
public class LuceneConstants {
   public static final String CONTENTS = "contents";
   public static final String FILE_NAME = "filename";
   public static final String FILE_PATH = "filepath";
   public static final int MAX_SEARCH = 10;
}

Searcher.java

此类用于读取对原始数据所做的索引，并使用Lucene库搜索数据。

package cn.xnip.lucene;
import java.io.File;
import java.io.IOException;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.index.CorruptIndexException;
import org.apache.lucene.queryParser.ParseException;
import org.apache.lucene.queryParser.QueryParser;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;
import org.apache.lucene.util.Version;
public class Searcher {
   IndexSearcher indexSearcher;
   QueryParser queryParser;
   Query query;
   public Searcher(String indexDirectoryPath) throws IOException {
      Directory indexDirectory = 
         FSDirectory.open(new File(indexDirectoryPath));
      indexSearcher = new IndexSearcher(indexDirectory);
      queryParser = new QueryParser(Version.LUCENE_36,
         LuceneConstants.CONTENTS,
         new StandardAnalyzer(Version.LUCENE_36));
   }
   public TopDocs search( String searchQuery) 
      throws IOException, ParseException {
      query = queryParser.parse(searchQuery);
      return indexSearcher.search(query, LuceneConstants.MAX_SEARCH);
   }
   public TopDocs search(Query query) throws IOException, ParseException {
      return indexSearcher.search(query, LuceneConstants.MAX_SEARCH);
   }
   public Document getDocument(ScoreDoc scoreDoc) 
      throws CorruptIndexException, IOException {
      return indexSearcher.doc(scoreDoc.doc);	
   }
   public void close() throws IOException {
      indexSearcher.close();
   }
}

LuceneTester.java

该类用于测试Lucene库的搜索功能。

package cn.xnip.lucene;
import java.io.IOException;
import org.apache.lucene.document.Document;
import org.apache.lucene.index.Term;
import org.apache.lucene.queryParser.ParseException;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.PrefixQuery;
import org.apache.lucene.search.TopDocs;
public class LuceneTester {
   String indexDir = "E:\\Lucene\\Index";
   String dataDir = "E:\\Lucene\\Data";
   Searcher searcher;
   public static void main(String[] args) {
      LuceneTester tester;
      try {
         tester = new LuceneTester();
         tester.searchUsingPrefixQuery("record1");
      } catch (IOException e) {
         e.printStackTrace();
      } catch (ParseException e) {
         e.printStackTrace();
      }
   }
   private void searchUsingPrefixQuery(String searchQuery)
      throws IOException, ParseException {
      searcher = new Searcher(indexDir);
      long startTime = System.currentTimeMillis();
      //create a term to search file name
      Term term = new Term(LuceneConstants.FILE_NAME, searchQuery);
      //create the term query object
      Query query = new PrefixQuery(term);
      //do the search
      TopDocs hits = searcher.search(query);
      long endTime = System.currentTimeMillis();
      System.out.println(hits.totalHits +
         " documents found. Time :" + (endTime - startTime) + "ms");
      for(ScoreDoc scoreDoc : hits.scoreDocs) {
         Document doc = searcher.getDocument(scoreDoc);
         System.out.println("File: "+ doc.get(LuceneConstants.FILE_PATH));
      }
      searcher.close();
   }
}

数据和索引目录创建

我们使用了来自record1.txt的10个文本文件到包含学生姓名和其他详细信息的record10.txt，并将它们放在目录E:\Lucene\Data.。 索引目录路径应创建为E:\Lucene\Index 。 在Lucene - Indexing Process一章中运行索引程序后，您可以看到在该文件夹中创建的索引文件列表。

运行程序 (Running the Program)

完成源，原始数据，数据目录，索引目录和索引的创建后，可以继续编译和运行程序。 为此，请保持LuceneTester.Java文件选项卡处于活动状态，并使用Eclipse IDE中提供的“运行”选项或使用Ctrl + F11编译并运行LuceneTester应用程序。 如果您的应用程序成功运行，它将在Eclipse IDE的控制台中打印以下消息 -

2 documents found. Time :20ms
File: E:\Lucene\Data\record1.txt
File: E:\Lucene\Data\record10.txt