Lucene example source code file (TestSimilarity.java)

This example Lucene source code file (TestSimilarity.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Lucene tags/keywords

booleanquery, collector, document, document, idfexplanation, io, ioexception, ioexception, override, override, scorer, simplesimilarity, term, term, termquery, util

The Lucene TestSimilarity.java source code

package org.apache.lucene.search;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import org.apache.lucene.util.LuceneTestCase;
import java.io.IOException;
import java.util.Collection;

import org.apache.lucene.index.FieldInvertState;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.RandomIndexWriter;
import org.apache.lucene.index.Term;
import org.apache.lucene.store.Directory;
import org.apache.lucene.analysis.MockAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.search.Explanation.IDFExplanation;

/** Similarity unit test.
 *
 *
 * @version $Revision: 1091277 $
 */
public class TestSimilarity extends LuceneTestCase {
  
  public static class SimpleSimilarity extends Similarity {
    @Override public float computeNorm(String field, FieldInvertState state) { return state.getBoost(); }
    @Override public float queryNorm(float sumOfSquaredWeights) { return 1.0f; }
    @Override public float tf(float freq) { return freq; }
    @Override public float sloppyFreq(int distance) { return 2.0f; }
    @Override public float idf(int docFreq, int numDocs) { return 1.0f; }
    @Override public float coord(int overlap, int maxOverlap) { return 1.0f; }
    @Override public IDFExplanation idfExplain(Collection<Term> terms, Searcher searcher) throws IOException {
      return new IDFExplanation() {
        @Override
        public float getIdf() {
          return 1.0f;
        }
        @Override
        public String explain() {
          return "Inexplicable";
        }
      };
    }
  }

  public void testSimilarity() throws Exception {
    Directory store = newDirectory();
    RandomIndexWriter writer = new RandomIndexWriter(random, store, 
        newIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(random))
        .setSimilarity(new SimpleSimilarity()));
    
    Document d1 = new Document();
    d1.add(newField("field", "a c", Field.Store.YES, Field.Index.ANALYZED));

    Document d2 = new Document();
    d2.add(newField("field", "a b c", Field.Store.YES, Field.Index.ANALYZED));
    
    writer.addDocument(d1);
    writer.addDocument(d2);
    IndexReader reader = writer.getReader();
    writer.close();

    IndexSearcher searcher = newSearcher(reader);
    searcher.setSimilarity(new SimpleSimilarity());

    Term a = new Term("field", "a");
    Term b = new Term("field", "b");
    Term c = new Term("field", "c");

    searcher.search(new TermQuery(b), new Collector() {
         private Scorer scorer;
         @Override
        public void setScorer(Scorer scorer) throws IOException {
           this.scorer = scorer; 
         }
         @Override
        public final void collect(int doc) throws IOException {
           assertEquals(1.0f, scorer.score());
         }
         @Override
        public void setNextReader(IndexReader reader, int docBase) {}
         @Override
        public boolean acceptsDocsOutOfOrder() {
           return true;
         }
       });

    BooleanQuery bq = new BooleanQuery();
    bq.add(new TermQuery(a), BooleanClause.Occur.SHOULD);
    bq.add(new TermQuery(b), BooleanClause.Occur.SHOULD);
    //System.out.println(bq.toString("field"));
    searcher.search(bq, new Collector() {
         private int base = 0;
         private Scorer scorer;
         @Override
        public void setScorer(Scorer scorer) throws IOException {
           this.scorer = scorer; 
         }
         @Override
        public final void collect(int doc) throws IOException {
           //System.out.println("Doc=" + doc + " score=" + score);
           assertEquals((float)doc+base+1, scorer.score());
         }
         @Override
        public void setNextReader(IndexReader reader, int docBase) {
           base = docBase;
         }
         @Override
        public boolean acceptsDocsOutOfOrder() {
           return true;
         }
       });

    PhraseQuery pq = new PhraseQuery();
    pq.add(a);
    pq.add(c);
    //System.out.println(pq.toString("field"));
    searcher.search(pq,
       new Collector() {
         private Scorer scorer;
         @Override
         public void setScorer(Scorer scorer) throws IOException {
          this.scorer = scorer; 
         }
         @Override
         public final void collect(int doc) throws IOException {
           //System.out.println("Doc=" + doc + " score=" + score);
           assertEquals(1.0f, scorer.score());
         }
         @Override
         public void setNextReader(IndexReader reader, int docBase) {}
         @Override
         public boolean acceptsDocsOutOfOrder() {
           return true;
         }
       });

    pq.setSlop(2);
    //System.out.println(pq.toString("field"));
    searcher.search(pq, new Collector() {
      private Scorer scorer;
      @Override
      public void setScorer(Scorer scorer) throws IOException {
        this.scorer = scorer; 
      }
      @Override
      public final void collect(int doc) throws IOException {
        //System.out.println("Doc=" + doc + " score=" + score);
        assertEquals(2.0f, scorer.score());
      }
      @Override
      public void setNextReader(IndexReader reader, int docBase) {}
      @Override
      public boolean acceptsDocsOutOfOrder() {
        return true;
      }
    });

    searcher.close();
    reader.close();
    store.close();
  }
}