Implementing Geospatial Bounding Box Search in Lucene 4.x

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.document.Field;
import org.apache.lucene.document.Field.Store;
import org.apache.lucene.document.FieldType;
import org.apache.lucene.document.IntField;
import org.apache.lucene.document.StoredField;
import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.IndexableField;
import org.apache.lucene.queries.function.ValueSource;
import org.apache.lucene.search.Filter;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.MatchAllDocsQuery;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.Sort;
import org.apache.lucene.search.TopDocs;
import org.apache.lucene.spatial.SpatialStrategy;
import org.apache.lucene.spatial.prefix.RecursivePrefixTreeStrategy;
import org.apache.lucene.spatial.prefix.tree.GeohashPrefixTree;
import org.apache.lucene.spatial.prefix.tree.SpatialPrefixTree;
import org.apache.lucene.spatial.query.SpatialArgs;
import org.apache.lucene.spatial.query.SpatialOperation;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.SimpleFSDirectory;
import org.apache.lucene.util.Version;

import com.spatial4j.core.context.SpatialContext;
import com.spatial4j.core.distance.DistanceUtils;
import com.spatial4j.core.shape.Point;
import com.spatial4j.core.shape.Shape;


public class SpatialSearch {
 
 private IndexWriter indexWriter;
 private IndexReader indexReader;
 private IndexSearcher searcher;
 private SpatialContext ctx;
 private SpatialStrategy strategy;
 
 public SpatialSearch(String indexPath) {
  
  StandardAnalyzer a = new StandardAnalyzer(Version.LUCENE_43);
  IndexWriterConfig iwc = new IndexWriterConfig(Version.LUCENE_43, a);
  Directory directory;
  
  try {
   directory = new SimpleFSDirectory(new File(indexPath));
   indexWriter = new IndexWriter(directory, iwc);
  } catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
  
  this.ctx = SpatialContext.GEO;
  
  SpatialPrefixTree grid = new GeohashPrefixTree(ctx, 11);
  this.strategy = new RecursivePrefixTreeStrategy(grid, "location");
 }
 
 public void indexDocuments() throws IOException {
  
  indexWriter.addDocument(newGeoDocument(1, "Bangalore", ctx.makePoint(12.9558, 77.620979)));
  indexWriter.addDocument(newGeoDocument(2, "Cubbon Park", ctx.makePoint(12.974045, 77.591995)));
  indexWriter.addDocument(newGeoDocument(3, "Tipu palace", ctx.makePoint(12.959365, 77.573792)));
  indexWriter.addDocument(newGeoDocument(4, "Bangalore palace", ctx.makePoint(12.998095, 77.592041)));
  indexWriter.addDocument(newGeoDocument(5, "Monkey Bar", ctx.makePoint(12.97018, 77.61219)));
 indexWriter.addDocument(newGeoDocument(6, "Chennai", ctx.makePoint(13.060422, 80.249583)));
 indexWriter.addDocument(newGeoDocument(7, "Elliot's Beach", ctx.makePoint(12.998976, 80.271286))); 
 indexWriter.addDocument(newGeoDocument(8, "Kapaleeshwar Temple", ctx.makePoint(13.033889, 80.269722)));

  
  indexWriter.commit();
  indexWriter.close();
 }
 

 private Document newGeoDocument(int id, String name, Shape shape) {

  FieldType ft = new FieldType();
  ft.setIndexed(true);
  ft.setStored(true);

  Document doc = new Document();
  
  doc.add(new IntField("id", id, Store.YES));
  doc.add(new Field("name", name, ft));
  for(IndexableField f:strategy.createIndexableFields(shape)) {
   doc.add(f);
  }
  
  doc.add(new StoredField(strategy.getFieldName(), ctx.toString(shape)));
  
  return doc;
 }
 
 public void setSearchIndexPath(String indexPath) throws IOException{
  this.indexReader = DirectoryReader.open(new SimpleFSDirectory(new File(indexPath)));
  this.searcher = new IndexSearcher(indexReader);
 }
 
public void searchBBox(Double minLat, Double minLng, Double maxLat, Double maxLng) throws IOException {

   SpatialArgs args = new SpatialArgs(SpatialOperation.IsWithin, ctx.makeRectangle(minLat, maxLat, minLng, maxLng));

   Filter filter = strategy.makeFilter(args);
   int limit = 10; 
   TopDocs topDocs = searcher.search(new MatchAllDocsQuery(), filter, limit);

   ScoreDoc[] scoreDocs = topDocs.scoreDocs; 
   for (ScoreDoc s : scoreDocs) { 
       Document doc = searcher.doc(s.doc); 
       System.out.println(doc.get("id") + "\t" + doc.get("name")); 
   } 
 }
  
}

 /**
  * @param args
  * @throws IOException 
  */
 public static void main(String[] args) throws IOException {
  // TODO Auto-generated method stub
  
  String indexPath = "/home/vishnu/lucene_practices/geo_spatial_index";
  
  SpatialSearch s = new SpatialSearch(indexPath);
  
  //Indexes sample documents
  s.indexDocuments();
  s.setSearchIndexPath(indexPath);
  
 //Get Places Within Chennai Bounding Box. 
 System.out.println("Places WithIn Chennai Bounding Box\n"); 
 s.searchBBox(12.9673, 80.184631, 13.15148, 80.306709); 


 //Get Places Within Bangalore Bounding Box.
 System.out.println("Places WithIn Bangalore Bounding Box"); 
 s.searchBBox(12.76805, 77.465202, 13.14355, 77.776749);

 }

}