PostgisValueConverterFactory.java

package com.vividsolutions.jump.datastore.postgis;

import java.sql.*;
import java.io.*;
import com.vividsolutions.jump.feature.*;
import com.vividsolutions.jts.geom.*;
import com.vividsolutions.jts.io.*;

import org.postgresql.*;
import com.vividsolutions.jump.datastore.*;
import com.vividsolutions.jump.datastore.jdbc.*;

/**
 *
 */
public class PostgisValueConverterFactory
{
  // should lazily init these
  private final ValueConverter WKT_GEOMETRY_MAPPER = new WKTGeometryValueConverter();
  private final ValueConverter WKB_GEOMETRY_MAPPER = new WKBGeometryValueConverter();

  private final Connection conn;
  private final WKBReader wkbReader = new WKBReader();
  private final WKTReader wktReader = new WKTReader();

  public PostgisValueConverterFactory(Connection conn) {
    this.conn = conn;
  }

  public ValueConverter getConverter(ResultSetMetaData rsm, int columnIndex)
      throws SQLException
  {
    String classname = rsm.getColumnClassName(columnIndex);
    String dbTypeName = rsm.getColumnTypeName(columnIndex);

    // MD - this is slow - is there a better way?
    if (dbTypeName.equalsIgnoreCase("geometry"))
        // WKB is now the normal way to store geometry in PostGIS [mmichaud 2007-05-13]
        return WKB_GEOMETRY_MAPPER;

    if (dbTypeName.equalsIgnoreCase("bytea"))
        return WKB_GEOMETRY_MAPPER;

    // handle the standard types
    ValueConverter stdConverter = ValueConverterFactory.getConverter(rsm, columnIndex);
    if (stdConverter != null)
      return stdConverter;

    // default - can always show it as a string!
    return ValueConverterFactory.STRING_MAPPER;
  }

  class WKTGeometryValueConverter implements ValueConverter
  {
    public AttributeType getType() { return AttributeType.GEOMETRY; }
    public Object getValue(ResultSet rs, int columnIndex)
        throws IOException, SQLException, ParseException
    {
      Object valObj = rs.getObject(columnIndex);
      if (valObj == null) return wktReader.read("GEOMETRYCOLLECTION EMPTY");
      else return wktReader.read(valObj.toString());
    }
  }

  class WKBGeometryValueConverter implements ValueConverter
  {
    public AttributeType getType() { return AttributeType.GEOMETRY; }
    public Object getValue(ResultSet rs, int columnIndex)
        throws IOException, SQLException, ParseException
    {
      byte[] bytes = rs.getBytes(columnIndex);

      //so rs.getBytes will be one of two things:
      //1. The actual bytes of the WKB if someone did ST_AsBinary
      //2. The bytes of hex representation of the WKB.

      //in the case of #1, according to the WKB spec, the byte value
      //can only be 0 or 1.
      //in the case of #2, it's a hex string, so values range from ascii 0-F
      //use this logic to determine how to process the bytes.

      Geometry geometry = null;
      if(bytes == null || bytes.length <= 0)
      {
         geometry = wktReader.read("GEOMETRYCOLLECTION EMPTY");
      }
      else
      {
          //assume it's the actual bytes (from ST_AsBinary)
          byte[] realWkbBytes = bytes;
          if(bytes[0] >= '0')
          {
              //ok, it's hex, convert hex string to actual bytes
              String hexString = new String(bytes);
              realWkbBytes = WKBReader.hexToBytes(hexString);
          }

          geometry = wkbReader.read(realWkbBytes);
      }

      return geometry;
    }
  }
}