[postgis-users] Buffering with JDBC

[shojka at web.de]

import java.sql.*; import java.util.*; import java.lang.*; import org.postgis.*; 

public class JavaGIS { public static void main(String[] args)

{

java.sql.Connection conn;

try

{

 Class.forName("org.postgresql.Driver");

 String url = "jdbc:postgresql://localhost:5432/database"; conn = DriverManager.getConnection(url, "postgres", ""); 

 ((org.postgresql.jdbc2.Jdbc2Connection)conn).addDataType("Geometry","org.postgis.PGgeometry");
 ((org.postgresql.jdbc2.Jdbc2Connection)conn).addDataType("box3d","org.postgis.PGbox3d");

 Statement s = conn.createStatement();

 ResultSet r = s.executeQuery("SELECT Buffer(GeometryFromText('POINT(10000 20000)',-1),20)");

 while( r.next() )

 {

 PGgeometry geom= (PGgeometry)r.getObject(1);

 if( geom.getType() = Geometry.POLYGON )

 {

 Polygon pl = (Polygon)geom.getGeometry();

 for( int r = 0; r < pl.numRings(); r++ )

 {

 LinearRing rng = pl.getRing(r);

 System.out.println("Ring: " + r);

 for( int p = 0; p < rng.numPoints(); p++ )

 {

 Point pt = rng.getPoint(p);

 System.out.println("Point: " + p);

 System.out.println(pt.toString());

 }

 }

 }

}

s.close();

conn.close();

}

catch( Exception e )

{

e.printStackTrace();

}

}

}

Dear PostGis users,

I want to use buffer function from POSTGIS but I simply cannot convert the result of query in a PGgeometry object. The line:

 PGgeometry geom= (PGgeometry)r.getObject(1);

results always in:

java.lang.ClassCastException: org.postgresql.util.PGobject

I got result as a strine when i insert in qery function Astext(), but when I want to work with geometry I am helpless. Has anyone an idea how this problem could be solved?

Thanking in advance


	
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