Lucene - StandardAnalyzer


Advertisements


Introduction

This is the most sofisticated analyzer and is capable of handling names, email address etc. It lowercases each token and removes common words and punctuation if any.

Class declaration

Following is the declaration for org.apache.lucene.analysis.StandardAnalyzer class:

public final class StandardAnalyzer
   extends StopwordAnalyzerBase

Fields

  • static int DEFAULT_MAX_TOKEN_LENGTH - Default maximum allowed token length

  • static Set<?> STOP_WORDS_SET - An unmodifiable set containing some common English words that are usually not useful for searching.

Class constructors

S.N.Constructor & Description
1

StandardAnalyzer(Version matchVersion)

Builds an analyzer with the default stop words (STOP_WORDS_SET).

2

StandardAnalyzer(Version matchVersion, File stopwords)

Deprecated. Use StandardAnalyzer(Version, Reader) instead.

3

StandardAnalyzer(Version matchVersion, Reader stopwords)

Builds an analyzer with the stop words from the given reader.

4

StandardAnalyzer(Version matchVersion, Set<?> stopWords)

Builds an analyzer with the given stop words.

Class methods

S.N.Method & Description
1

protected Reusable Analyzer Base. Token Stream Components create Components(String fieldName, Reader reader)

Creates a new ReusableAnalyzerBase.TokenStreamComponents instance for this analyzer.

2

int getMaxTokenLength()

3

void setMaxTokenLength(int length)

Set maximum allowed token length.

Methods inherited

This class inherits methods from the following classes:

  • org.apache.lucene.analysis.StopwordAnalyzerBase

  • org.apache.lucene.analysis.ReusableAnalyzerBase

  • org.apache.lucene.analysis.Analyzer

  • java.lang.Object

Usage

private void displayTokenUsingStandardAnalyzer() throws IOException{
   String text 
      = "Lucene is simple yet powerful java based search library.";
   Analyzer analyzer = new StandardAnalyzer(Version.LUCENE_36);
   TokenStream tokenStream 
      = analyzer.tokenStream(LuceneConstants.CONTENTS,
        new StringReader(text));
   TermAttribute term = tokenStream.addAttribute(TermAttribute.class);
   while(tokenStream.incrementToken()) {
      System.out.print("[" + term.term() + "] ");
   }
}

Example Application

Let us create a test Lucene application to test search using BooleanQuery.

StepDescription
1Create a project with a name LuceneFirstApplication under a package com.tutorialspoint.lucene as explained in the Lucene - First Application chapter. You can also use the project created in Lucene - First Application chapter as such for this chapter to understand searching process.
2Create LuceneConstants.java as explained in the Lucene - First Application chapter. Keep rest of the files unchanged.
3Create LuceneTester.java as mentioned below.
4Clean and Build the application to make sure business logic is working as per the requirements.

LuceneConstants.java

This class is used to provide various constants to be used across the sample application.

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;
}

LuceneTester.java

This class is used to test the searching capability of lucene library.

package com.tutorialspoint.lucene;

import java.io.IOException;
import java.io.StringReader;

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.StandardAnalyzer;
import org.apache.lucene.analysis.tokenattributes.TermAttribute;
import org.apache.lucene.util.Version;

public class LuceneTester {
	
   public static void main(String[] args) {
      LuceneTester tester;

      tester = new LuceneTester();
   
      try {
         tester.displayTokenUsingStandardAnalyzer();
      } catch (IOException e) {
         e.printStackTrace();
      }
   }

   private void displayTokenUsingStandardAnalyzer() throws IOException{
      String text 
         = "Lucene is simple yet powerful java based search library.";
      Analyzer analyzer = new StandardAnalyzer(Version.LUCENE_36);
      TokenStream tokenStream = analyzer.tokenStream(
         LuceneConstants.CONTENTS, new StringReader(text));
      TermAttribute term = tokenStream.addAttribute(TermAttribute.class);
      while(tokenStream.incrementToken()) {
         System.out.print("[" + term.term() + "] ");
      }
   }
}

Running the Program:

Once you are done with creating source, you are ready for this step which is compiling and running your program. To do this, Keep LuceneTester.Java file tab active and use either Run option available in the Eclipse IDE or use Ctrl + F11 to compile and run your LuceneTester application. If everything is fine with your application, this will print the following message in Eclipse IDE's console:

[lucene] [simple] [yet] [powerful] [java] [based] [search] [library] 

lucene_analysis.htm

Advertisements