jtsgiswrapper.java

postGIS是一个能够使用postSQL数据库来管理GIS数据的小程序,充分发挥了该数据库的空间管理功能,非常有用哦

/*
 * JtsWrapper.java
 * 
 * Allows transparent usage of JTS Geometry classes via PostgreSQL JDBC driver
 * connected to a PostGIS enabled PostgreSQL server.
 * 
 * (C) 2005 Markus Schaber, [e-mail]
 * 
 * This library is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation, either version 2.1 of the License.
 * 
 * This library is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
 * details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA or visit the web at
 * http://www.gnu.org.
 * 
 * $Id: JtsGisWrapper.java 1977 2005-10-20 15:58:52Z mschaber $
 */

package org.postgis.jts;

import org.postgresql.Driver;
import org.postgresql.PGConnection;

import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;

/**
 * JtsGisWrapper
 * 
 * Wraps the PostGreSQL Driver to add the JTS/PostGIS Object Classes.
 * 
 * This method currently works with J2EE DataSource implementations, and with
 * DriverManager framework.
 * 
 * Simply replace the "jdbc:postgresql:" with a "jdbc:postgresql_JTS" in the
 * jdbc URL.
 * 
 * @author [e-mail]
 * 
 */
public class JtsGisWrapper extends Driver {

    private static final String POSTGRES_PROTOCOL = "jdbc:postgresql:";
    private static final String POSTGIS_PROTOCOL = "jdbc:postgresql_JTS:";
    public static final String REVISION = "$Revision: 1977 $";

    public JtsGisWrapper() {
        super();
    }

    static {
        try {
            // Analogy to org.postgresql.Driver
            java.sql.DriverManager.registerDriver(new JtsGisWrapper());
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    /**
     * Creates a postgresql connection, and then adds the PostGIS data types to
     * it calling addpgtypes()
     * 
     * @param url the URL of the database to connect to
     * @param info a list of arbitrary tag/value pairs as connection arguments
     * @return a connection to the URL or null if it isnt us
     * @exception SQLException if a database access error occurs
     * 
     * @see java.sql.Driver#connect
     * @see org.postgresql.Driver
     */
    public java.sql.Connection connect(String url, Properties info) throws SQLException {
        url = mangleURL(url);
        Connection result = super.connect(url, info);
        addGISTypes((PGConnection) result);
        return result;
    }

    /**
     * adds the JTS/PostGIS Data types to a PG Connection.
     * 
     * @throws SQLException
     */
    public static void addGISTypes(PGConnection pgconn) throws SQLException {
        pgconn.addDataType("geometry", org.postgis.jts.JtsGeometry.class);
        pgconn.addDataType("box3d", org.postgis.PGbox3d.class);
        pgconn.addDataType("box2d", org.postgis.PGbox2d.class);
    }

    /**
     * Mangles the PostGIS URL to return the original PostGreSQL URL
     */
    public static String mangleURL(String url) throws SQLException {
        if (url.startsWith(POSTGIS_PROTOCOL)) {
            return POSTGRES_PROTOCOL + url.substring(POSTGIS_PROTOCOL.length());
        } else {
            throw new SQLException("Unknown protocol or subprotocol in url " + url);
        }
    }

    /**
     * Returns true if the driver thinks it can open a connection to the given
     * URL. Typically, drivers will return true if they understand the
     * subprotocol specified in the URL and false if they don't. Our protocols
     * start with jdbc:postgresql_postGIS:
     * 
     * @see java.sql.Driver#acceptsURL
     * @param url the URL of the driver
     * @return true if this driver accepts the given URL
     * @exception SQLException if a database-access error occurs (Dont know why
     *                it would *shrug*)
     */
    public boolean acceptsURL(String url) throws SQLException {
        try {
            url = mangleURL(url);
        } catch (SQLException e) {
            return false;
        }
        return super.acceptsURL(url);
    }

    /**
     * Gets the underlying drivers major version number
     * 
     * @return the drivers major version number
     */

    public int getMajorVersion() {
        return super.getMajorVersion();
    }

    /**
     * Get the underlying drivers minor version number
     * 
     * @return the drivers minor version number
     */
    public int getMinorVersion() {
        return super.getMinorVersion();
    }

    /**
     * Returns our own CVS version plus postgres Version
     */
    public static String getVersion() {
        return "JtsGisWrapper " + REVISION + ", wrapping " + Driver.getVersion();
    }
}