Lucene - 字首查詢 (PrefixQuery)

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PrefixQuery 用於匹配索引以指定字串開頭的文件。

類宣告

以下是org.apache.lucene.search.PrefixQuery類的宣告：

public class PrefixQuery
   extends MultiTermQuery

類建構函式

下表顯示了不同的類建構函式：

類方法

下表顯示了不同的類方法：

繼承的方法

此類繼承自以下類的方法：

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

用法

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();
}

示例應用程式

讓我們建立一個測試Lucene應用程式來測試使用PrefixQuery進行搜尋。

LuceneConstants.java

此類用於提供可在示例應用程式中使用的各種常量。

package com.tutorialspoint.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

此類用於讀取對原始資料進行的索引，並使用Lucene庫搜尋資料。

package com.tutorialspoint.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

此類用於測試Lucene庫的搜尋能力。

package com.tutorialspoint.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();
   }
}

資料和索引目錄建立

我們使用了10個文字檔案，從record1.txt到record10.txt，包含學生姓名和其他詳細資訊，並將它們放在E:\Lucene\Data目錄中。測試資料。應建立索引目錄路徑E:\Lucene\Index。在Lucene - 索引過程章節中執行索引程式後，您可以在該資料夾中看到建立的索引檔案列表。

執行程式

完成原始碼、原始資料、資料目錄、索引目錄和索引的建立後，您可以透過編譯和執行程式繼續操作。為此，請保持LuceneTester.Java檔案選項卡處於活動狀態，並使用Eclipse IDE中提供的“執行”選項，或使用Ctrl + F11編譯並執行您的LuceneTester應用程式。如果您的應用程式成功執行，它將在Eclipse IDE的控制檯中列印以下訊息：

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