[postgis-users] How to instanziate the Geometry class from the geometry string?

[martinelli at pi.ingv.it]

Hi Markus,
your tip wasn't applicable to the ODMG interface from OJB, but it gave me
the idea about the solution (it worked for Point class), setting the
jdbc-type="VARBINARY".
Here is the snippet in case someone may benefit from it:

public class Point2ClassConversion implements FieldConversion {
  private BinaryParser parser = new BinaryParser();
  private BinaryWriter writer = new BinaryWriter();
  public Object javaToSql(Object source) throws ConversionException {
    MyClass point = (MyClass)source;
    Point gisPoint = new Point(point.getLong(), javaPoint.getLat());
    gisPoint.setSrid(point.getSrid());

    byte[] sqlPoint = writer.writeBinary(gisPoint);

    return puntoSql;
  }
  public Object sqlToJava(Object source) throws ConversionException {
    byte[] sqlPoint = (byte[])source;
    StringBuffer buffer = new StringBuffer();

    for (int count=0; count<sqlPoint.length; count++) {
      buffer.append(new Character((char)sqlPoint[count]));
    }
    Geometry gisPoint = parser.parse(buffer.toString());

    MyClass point = new MyClass(((Point)geom).x, ((Point)geom).y);
    point.setSrid(((Point)geom).getSrid());

    return point;
  }
}

Regards,
Francesco.


> Hi, Francesco,
>
> martinelli at pi.ingv.it wrote:
>
>> during my last email I thought I got the solution, as method
>> org.postgis.binary.binaryWriter.writeHexed()
>>
>> returned the same string as I received from the database, and indeed the
>> same string as showed querying pgadmin3.
>>
>> Nevertheless, when I moved my sptes forward and tried to really connect
>> to
>> the databse for updating the geometry data, the following error came up:
>> org.postgresql.util.PSQLException: ERROR: column "the_geom" is of type
>> geometry but expression is of type character
>
> Did you wrap the String into an appropriate PGobject, and use
> setObject() to set it in the prepared statement?
>
> If you use setString(), the JDBC driver tells the server that the type
> is Text.
>
> Another possibility to cope with this is using an explicit cast in the
> statement, like:
>
> INSERT INTO mytable (the_geom) VALUES (?::geometry);
>
> HTH,
> Markus
>
>
> --
> Markus Schaber | Logical Tracking&Tracing International AG
> Dipl. Inf.     | Software Development GIS
>
> Fight against software patents in Europe! www.ffii.org
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