import org.apache.lucene.search.similarities.DFRSimilarity; //导入依赖的package包/类
public DFRSimilarityProvider(String name, Settings settings, Settings indexSettings) {
    super(name);
    BasicModel basicModel = parseBasicModel(settings);
    AfterEffect afterEffect = parseAfterEffect(settings);
    Normalization normalization = parseNormalization(settings);
    this.similarity = new DFRSimilarity(basicModel, afterEffect, normalization);
}
 

import org.apache.lucene.search.similarities.DFRSimilarity; //导入依赖的package包/类
@Before
public void setupIndex() throws IOException {
    dirUnderTest = newDirectory();
    List<Similarity> sims = Arrays.asList(
            new ClassicSimilarity(),
            new SweetSpotSimilarity(), // extends Classic
            new BM25Similarity(),
            new LMDirichletSimilarity(),
            new BooleanSimilarity(),
            new LMJelinekMercerSimilarity(0.2F),
            new AxiomaticF3LOG(0.5F, 10),
            new DFISimilarity(new IndependenceChiSquared()),
            new DFRSimilarity(new BasicModelBE(), new AfterEffectB(), new NormalizationH1()),
            new IBSimilarity(new DistributionLL(), new LambdaDF(), new NormalizationH3())
        );
    similarity = sims.get(random().nextInt(sims.size()));

    indexWriterUnderTest = new RandomIndexWriter(random(), dirUnderTest, newIndexWriterConfig().setSimilarity(similarity));
    for (int i = 0; i < docs.length; i++) {
        Document doc = new Document();
        doc.add(newStringField("id", "" + i, Field.Store.YES));
        doc.add(newField("field", docs[i], Store.YES));
        indexWriterUnderTest.addDocument(doc);
    }
    indexWriterUnderTest.commit();
    indexWriterUnderTest.forceMerge(1);
    indexWriterUnderTest.flush();


    indexReaderUnderTest = indexWriterUnderTest.getReader();
    searcherUnderTest = newSearcher(indexReaderUnderTest);
    searcherUnderTest.setSimilarity(similarity);
}
 

import org.apache.lucene.search.similarities.DFRSimilarity; //导入依赖的package包/类
/** dfr with default parameters */
public void test() throws Exception {
  Similarity sim = getSimilarity("text");
  assertEquals(DFRSimilarity.class, sim.getClass());
  DFRSimilarity dfr = (DFRSimilarity) sim;
  assertEquals(BasicModelIF.class, dfr.getBasicModel().getClass());
  assertEquals(AfterEffectB.class, dfr.getAfterEffect().getClass());
  assertEquals(NormalizationH2.class, dfr.getNormalization().getClass());
}
 

import org.apache.lucene.search.similarities.DFRSimilarity; //导入依赖的package包/类
/** dfr with parameterized normalization */
public void testParameters() throws Exception {
  Similarity sim = getSimilarity("text_params");
  assertEquals(DFRSimilarity.class, sim.getClass());
  DFRSimilarity dfr = (DFRSimilarity) sim;
  assertEquals(BasicModelIF.class, dfr.getBasicModel().getClass());
  assertEquals(AfterEffectB.class, dfr.getAfterEffect().getClass());
  assertEquals(NormalizationH3.class, dfr.getNormalization().getClass());
  NormalizationH3 norm = (NormalizationH3) dfr.getNormalization();
  assertEquals(900f, norm.getMu(), 0.01f);
}
 

import org.apache.lucene.search.similarities.DFRSimilarity; //导入依赖的package包/类
/** LUCENE-3566 */
public void testParameterC() throws Exception {
  Similarity sim = getSimilarity("text_paramc");
  assertEquals(DFRSimilarity.class, sim.getClass());
  DFRSimilarity dfr = (DFRSimilarity) sim;
  assertEquals(BasicModelP.class, dfr.getBasicModel().getClass());
  assertEquals(AfterEffectL.class, dfr.getAfterEffect().getClass());
  assertEquals(NormalizationH2.class, dfr.getNormalization().getClass());
  NormalizationH2 norm = (NormalizationH2) dfr.getNormalization();
  assertEquals(7f, norm.getC(), 0.01f);
}
 

import org.apache.lucene.search.similarities.DFRSimilarity; //导入依赖的package包/类
@Override
public Similarity getSimilarity() {
  DFRSimilarity sim = new DFRSimilarity(basicModel, afterEffect, normalization);
  sim.setDiscountOverlaps(discountOverlaps);
  return sim;
}