[postgis-users] JAVA and post GIS

[Gilbert, Antoine]

I don't know the center() function, but you can try the centroid() one

 

This query was working for me (my spatial column is geom)

 

select AsBinary(centroid(geom)) as mycenter from "fr_lamb_mg_1_region"

 

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From: Fatemeh Abbasinejad [mailto:fabbasinejad at yahoo.com] 
Sent: January 30, 2006 4:48 PM
To: PostGIS Users Discussion
Subject: RE: [postgis-users] JAVA and post GIS

 

AsBinary() and AsText() require a "geometry object as input. My object
is of type "Point" and will non execute the query.I tried executing the
query alone.Am I doing something wrong? Do you know how I can convert
Point or types "circle" into binary?

I am also using postgis_1.1.0.jar.

 



"Gilbert, Antoine" <AGilbert at korem.com> wrote:

	Yes

	 

	I'm not a postgis expert, but I think in your case it should be 

	 

	ResultSet rs = s.executeQuery("select
(AsBinary(center(geometry)))) as mycenter from land");

	 

	You have to convert the geometry in the binary format

	 

	You can use AsText too and use new PGgeometry(rs.getString(1))
or something like that I think

	 

	I'm using postgis_1_0_0.jar

	 

	
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	From: Fatemeh Abbasinejad [mailto:fabbasinejad at yahoo.com] 
	Sent: January 30, 2006 3:19 PM
	To: PostGIS Users Discussion
	Subject: RE: [postgis-users] JAVA and post GIS

	 

	Hi

	 I tried what you did but the program wouln't even compile. I
have a table named "land" which has an attribute"geometry" of type
"circle". I want to retrieve the center of the circle which is of type
"point" as defined by postGIS.Here is my Program

	 

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

	public class JavaGIS3 { 
	  public static void main(String[] args) 
	  { 
	    java.sql.Connection conn; 
	    try 
	    { 
	      Class.forName("org.postgresql.Driver"); 
	      String url = "jdbc:postgresql://localhost:5432/dcmms"; 
	      conn = DriverManager.getConnection(url, "postgres",
"abcde"); 
	      Statement s = conn.createStatement(); 
	      ResultSet rs = s.executeQuery("select (center(geometry))as
mycenter from land"); 
	      ResultSetMetaData rsmd = rs.getMetaData();
	      for(int i=0;rs.next();i++){
	       Geometry geometry = new
BinaryParser().parse(rs.getBytes(1));
	          if(geometry.getType()==geometry.POINT){
	           System.out.println("Finally retrieved geometry
object!")
	          }
	      }
	      s.close(); 
	      conn.close(); 
	    } 
	    catch( Exception e ) 
	    { 
	      e.printStackTrace(); 
	    }
	  }
	}

	 

	 

	I did what you had said in your email but it would give an
error:

	BinaryParser cannot be resolved to a type

	 

	What should I do? Did you compile your program?

	
	"Gilbert, Antoine" <AGilbert at korem.com> wrote:

		Hi

		 

		Here is my example using postgis_1_0_0.jar

		 

		Connection connection = TestUtils.getTestConnection();

		        Statement stmt = connection.createStatement();

		        ResultSet rs = stmt.executeQuery("select
AsBinary(geom) as geom from \"rue_test_polyline\"");

		        ResultSetMetaData rsmd = rs.getMetaData();

		        for(int i=0;rs.next();i++){

		            Geometry geometry = new
BinaryParser().parse(rs.getBytes(1));

	
if(geometry.getType()==geometry.MULTILINESTRING){

		                MultiLineString multiline =
((MultiLineString)geometry);

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

		                System.out.println("ligne "+i+" contient
"+multiline.numLines()+" segment(s)");

		                for(int j=0;j<multiline.numLines();j++)

		                    System.out.println("    segment
"+j+":"+multiline.getLine(j).numPoints()+" points");

		            }

		        }

		        stmt.close();

		        connection.close();

		 

		
  _____  


		From: Fatemeh Abbasinejad
[mailto:fabbasinejad at yahoo.com] 
		Sent: January 30, 2006 3:43 AM
		To: postgis-users at postgis.refractions.net
		Subject: [postgis-users] JAVA and post GIS

		 

		I am new to PostGIS. Does anyone know how we can
retrieve our defined data types 
		(like point,circle,...) from a ResultSet in java. I used
getObject but it didn't work. 

		-fatemeh

		
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