Geometric Data Types

PostgreSQL™ has a set of data types that can store geometric features into a table. These include single points, lines, and polygons. We support these types in Java with the org.postgresql.geometric package. Please consult the Javadoc for the details of available classes and features metioned in Chapter 12, Further Reading.

Example 9.1. Using the CIRCLE datatype JDBC

import java.sql.*;

import org.postgresql.geometric.PGpoint; import org.postgresql.geometric.PGcircle;

public class GeometricTest {

public static void main(String args[]) throws Exception {
    Class.forName("org.postgresql.Driver");
    String url = "jdbc:postgresql://localhost:5432/test";

    Connection conn = DriverManager.getConnection(url,"test","");

    Statement stmt = conn.createStatement();
    stmt.execute("CREATE TEMP TABLE geomtest(mycirc circle)");
    stmt.close();

    insertCircle(conn);
    retrieveCircle(conn);
    conn.close();
}

private static void insertCircle(Connection conn) throws SQLException {

    PGpoint center = new PGpoint(1, 2.5);
    double radius = 4;
    PGcircle circle = new PGcircle(center, radius);

    PreparedStatement ps = conn.prepareStatement("INSERT INTO geomtest(mycirc) VALUES (?)");
    ps.setObject(1, circle);
    ps.executeUpdate();
    ps.close();
}

private static void retrieveCircle(Connection conn) throws SQLException {
    Statement stmt = conn.createStatement();
    ResultSet rs = stmt.executeQuery("SELECT mycirc, area(mycirc) FROM geomtest");
    rs.next();
    PGcircle circle = (PGcircle)rs.getObject(1);
    double area = rs.getDouble(2);

    PGpoint center = circle.center;
    double radius = circle.radius;

    System.out.println("Center (X, Y) = (" + center.x + ", " + center.y + ")");
    System.out.println("Radius = " + radius);
    System.out.println("Area = " + area);
}

}

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