package com.fox.facet;import java.io.IOException;import java.util.ArrayList;import java.util.List;import org.apache.lucene.analysis.core.WhitespaceAnalyzer;import org.apache.lucene.document.Document;import org.apache.lucene.facet.index.FacetFields;import org.apache.lucene.facet.params.FacetSearchParams;import org.apache.lucene.facet.search.CountFacetRequest;import org.apache.lucene.facet.search.DrillDownQuery;import org.apache.lucene.facet.search.FacetResult;import org.apache.lucene.facet.search.FacetsCollector;import org.apache.lucene.facet.taxonomy.CategoryPath;import org.apache.lucene.facet.taxonomy.TaxonomyReader;import org.apache.lucene.facet.taxonomy.directory.DirectoryTaxonomyReader;import org.apache.lucene.facet.taxonomy.directory.DirectoryTaxonomyWriter;import org.apache.lucene.index.DirectoryReader;import org.apache.lucene.index.IndexWriter;import org.apache.lucene.index.IndexWriterConfig;import org.apache.lucene.search.IndexSearcher;import org.apache.lucene.search.MatchAllDocsQuery;import org.apache.lucene.store.Directory;import org.apache.lucene.store.RAMDirectory;import org.apache.lucene.util.Version;/* * 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. *//** Shows simple usage of faceted indexing and search. */public class SimpleFacetsExample {    private final Directory indexDir = new RAMDirectory();    private final Directory taxoDir = new RAMDirectory();    /** Empty constructor */    public SimpleFacetsExample() {    }    private void add(IndexWriter indexWriter, FacetFields facetFields, String... categoryPaths) throws IOException {        Document doc = new Document();        List<CategoryPath> paths = new ArrayList<CategoryPath>();        for (String categoryPath : categoryPaths) {            paths.add(new CategoryPath(categoryPath, ‘/‘));        }        facetFields.addFields(doc, paths);        indexWriter.addDocument(doc);    }    /** Build the example index. */    private void index() throws IOException {        IndexWriter indexWriter = new IndexWriter(indexDir, new IndexWriterConfig(Version.LUCENE_43, new WhitespaceAnalyzer(                Version.LUCENE_43)));        // Writes facet ords to a separate directory from the main index        DirectoryTaxonomyWriter taxoWriter = new DirectoryTaxonomyWriter(taxoDir);        // Reused across documents, to add the necessary facet fields        FacetFields facetFields = new FacetFields(taxoWriter);        add(indexWriter, facetFields, "Author/Bob", "Publish Date/2010/10/15");        add(indexWriter, facetFields, "Author/Lisa", "Publish Date/2010/10/20");        add(indexWriter, facetFields, "Author/Lisa", "Publish Date/2012/1/1");        add(indexWriter, facetFields, "Author/Susan", "Publish Date/2012/1/7");        add(indexWriter, facetFields, "Author/Frank", "Publish Date/1999/5/5");        indexWriter.close();        taxoWriter.close();    }    /** User runs a query and counts facets. */    private List<FacetResult> search() throws IOException {        DirectoryReader indexReader = DirectoryReader.open(indexDir);        IndexSearcher searcher = new IndexSearcher(indexReader);        TaxonomyReader taxoReader = new DirectoryTaxonomyReader(taxoDir);        // Count both "Publish Date" and "Author" dimensions        FacetSearchParams fsp = new FacetSearchParams(new CountFacetRequest(new CategoryPath("Publish Date"), 10),                new CountFacetRequest(new CategoryPath("Author"), 10));        // Aggregatses the facet counts        FacetsCollector fc = FacetsCollector.create(fsp, searcher.getIndexReader(), taxoReader);        // MatchAllDocsQuery is for "browsing" (counts facets        // for all non-deleted docs in the index); normally        // you‘d use a "normal" query, and use MultiCollector to        // wrap collecting the "normal" hits and also facets:        searcher.search(new MatchAllDocsQuery(), fc);        // Retrieve results        List<FacetResult> facetResults = fc.getFacetResults();        indexReader.close();        taxoReader.close();        return facetResults;    }    /** User drills down on ‘Publish Date/2010‘. */    private List<FacetResult> drillDown() throws IOException {        DirectoryReader indexReader = DirectoryReader.open(indexDir);        IndexSearcher searcher = new IndexSearcher(indexReader);        TaxonomyReader taxoReader = new DirectoryTaxonomyReader(taxoDir);        // Now user drills down on Publish Date/2010:        FacetSearchParams fsp = new FacetSearchParams(new CountFacetRequest(new CategoryPath("Author"), 10));        DrillDownQuery q = new DrillDownQuery(fsp.indexingParams, new MatchAllDocsQuery());        q.add(new CategoryPath("Publish Date/2010", ‘/‘));        FacetsCollector fc = FacetsCollector.create(fsp, searcher.getIndexReader(), taxoReader);        searcher.search(q, fc);        // Retrieve results        List<FacetResult> facetResults = fc.getFacetResults();        indexReader.close();        taxoReader.close();        return facetResults;    }    /** Runs the search example. */    public List<FacetResult> runSearch() throws IOException {        index();        return search();    }    /** Runs the drill-down example. */    public List<FacetResult> runDrillDown() throws IOException {        index();        return drillDown();    }    /** Runs the search and drill-down examples and prints the results. */    public static void main(String[] args) throws Exception {        System.out.println("Facet counting example:");        System.out.println("-----------------------");        List<FacetResult> results = new SimpleFacetsExample().runSearch();        for (FacetResult res : results) {            System.out.println(res);        }        System.out.println("\n");        System.out.println("Facet drill-down example (Publish Date/2010):");        System.out.println("---------------------------------------------");        results = new SimpleFacetsExample().runDrillDown();        for (FacetResult res : results) {            System.out.println(res);        }    }}

Facet counting example:-----------------------Request: Publish Date nRes=10 nLbl=10Num valid Descendants (up to specified depth): 3    Publish Date (0.0)          Publish Date/2012 (2.0)          Publish Date/2010 (2.0)          Publish Date/1999 (1.0)Request: Author nRes=10 nLbl=10Num valid Descendants (up to specified depth): 4    Author (0.0)          Author/Lisa (2.0)          Author/Frank (1.0)          Author/Susan (1.0)          Author/Bob (1.0)Facet drill-down example (Publish Date/2010):---------------------------------------------Request: Author nRes=10 nLbl=10Num valid Descendants (up to specified depth): 2    Author (0.0)          Author/Lisa (1.0)          Author/Bob (1.0)