Application: gvSIG desktop » gvSIG data provider for WFS

/**

 * gvSIG. Desktop Geographic Information System.

 *

 * Copyright (C) 2007-2013 gvSIG Association.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 3

 * of the License, or (at your option) any later version.

 *

 * This program 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 General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,

 * MA  02110-1301, USA.

 *

 * For any additional information, do not hesitate to contact us

 * at info AT gvsig.com, or visit our website www.gvsig.com.

 */

package org.gvsig.remoteclient.wfs;

import java.io.File;

import java.io.FileReader;

import java.io.IOException;

import java.io.Reader;

import java.net.ConnectException;

import java.net.URL;

import java.util.ArrayList;

import java.util.Iterator;

import java.util.List;

import org.kxml2.io.KXmlParser;

import org.xmlpull.v1.XmlPullParserException;

import org.gvsig.compat.CompatLocator;

import org.gvsig.compat.lang.StringUtils;

import org.gvsig.remoteclient.utils.CapabilitiesTags;

import org.gvsig.remoteclient.utils.EncodingXMLParser;

import org.gvsig.remoteclient.utils.Utilities;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

/**

 * @author Jorge Piera Llodr? (piera_jor@gva.es)

 */

public class WFSProtocolHandlerFactory {

        private static Logger logger = LoggerFactory.getLogger(WFSProtocolHandlerFactory.class);

        public WFSProtocolHandler wFSProtocolHandler;

        private static final StringUtils stringUtils = CompatLocator.getStringUtils();

        private static ArrayList supportedVersions = new ArrayList();

        static {

        supportedVersions.add("1.1.0");

                supportedVersions.add("1.0.0");

        }

        /**

         * M?todo que dada una respuesta de getCapabilities y un iterador sobre una

         * coleccion de WFSClient's ordenada descendentemente devuelve el cliente

         * cuya version es igual o inmediatamente inferior

         *

         * @param caps Capabilities con la respuesta del servidor

         * @param clients Iterador de conjunto ordenado descendientemente

         *

         * @return cliente cuya version es igual o inmediatamente inferior

         * @throws IllegalAccessException

         * @throws InstantiationException

         * 

         */

        private static String getDriverVersion(String version, Iterator clients) throws InstantiationException, IllegalAccessException {

                while (clients.hasNext()) {

                        String clientVersion = (String)clients.next();

                        int ret = version.compareTo(clientVersion);

                        if (ret >= 0) {

                                return clientVersion;

                        }

                }

                return null;

        }

        /**

         * Establece la versi?n con la que se comunicar? con el servidor y devuelve

         * el objeto Capabilities obtenido con dicha versi?n

         *

         * @param host maquina con la que se negocia

         *

         * @return instancia de un cliente capaz de negociar con el host que se

         *         pasa como par?metro

         */

        public static WFSProtocolHandler negotiate(String host, boolean ignoreCache) throws ConnectException, IOException {

                if (supportedVersions.size() == 0){

                        return null;

                }

                try        {                

                        String highestVersionSupportedByServer  = getSuitableWFSVersion(host,"", ignoreCache);

                        if (supportedVersions.contains(highestVersionSupportedByServer))

                        {

                                // we support the highest version supported by the server

                                // this is the best case 

                                return createVersionDriver(highestVersionSupportedByServer);

                        }

                        else

                        {

                                // in case we dont support the highest version from the server

                                // we start the negotiation process in which we have to get the higest version

                                // the WFS supports and we are able to read.

                                Iterator iVersion = supportedVersions.iterator();

                                String wfsVersion;

                                String gvSIGVersion;

                                while (iVersion.hasNext()) { 

                                        gvSIGVersion = (String)iVersion.next();

                                        wfsVersion = getSuitableWFSVersion(host,gvSIGVersion, ignoreCache);

                                        //TODO:

                                        //compare with the version returned by the WMS!!!!!

                                        // send GetCapabilities and read the version to compare.

                                        int res = wfsVersion.compareTo(gvSIGVersion);

                                        if (res == 0) { //Si es la misma que nuestra version                

                                                return createVersionDriver(gvSIGVersion);

                                        } else if (res > 0) { //Si es mayor que nuestra version

                                                throw new Exception("Server Version too high: " + wfsVersion);

                                        } else { //Si es menor que nuestra version

                                                //Obtenemos la primera version menor o igual que tengamos

                                                String lowerVersion = WFSProtocolHandlerFactory.getDriverVersion(wfsVersion, iVersion);

                                                if (lowerVersion == null) { //Si no hay ninguna

                                                        throw new Exception("Lowest server version is " + wfsVersion);

                                                } else {

                                                        if (lowerVersion.equals(wfsVersion)) { 

                                                                return createVersionDriver(lowerVersion);

                                                        } else { //Si hay una version menor que la que retorno el servidor

                                                                //iV = lower;

                                                        }

                                                }

                                        }

                                }

                        }//case we had to start the negotiation process.

                        return null; // if it did not find any suitable version.        

                }

                catch(ConnectException conEx)

                {

                        throw conEx;

                }

                catch(IOException ioEx)

                {

                        throw ioEx;

                }        

                catch(Exception e)

                {

                        logger.warn("Can't negotiate version for host '"+host+"'.",e);

                        return null;

                }

        }

        /**

         * Sends a GetCapabilities to the WFS server to get the version

         * if the version parameter is null, the WFS will return the highest version supported

         * if not it will return the lower highest version than the one requested.

         * @param host

         * @param version

         * @return suitable version supported by the server 

         */

        private static String getSuitableWFSVersion(String host, String _version, boolean ignoreCache) throws ConnectException, IOException {             

                String request = WFSProtocolHandler.buildCapabilitiesSuitableVersionRequest(host, _version);

                String version = new String(); 

                Reader reader = null;

                File file = null;

                try {           

                        URL url = new URL(request);

                        if( ignoreCache ) {

                            Utilities.removeURL(url);

                        }

                        file = Utilities.downloadFile(url, "wfs-suitable-version", null);

                        reader = new FileReader(file);

                        EncodingXMLParser kxmlParser = new EncodingXMLParser();

                        kxmlParser.setInput(reader);                

                        kxmlParser.nextTag();

                        if ( kxmlParser.getEventType() != KXmlParser.END_DOCUMENT ) {                    

                                String tag = kxmlParser.getName();

                                if (stringUtils.split(tag, ":").length == 2){

                                        tag = stringUtils.split(tag, ":")[1];

                                }

                                if ((tag.compareTo(CapabilitiesTags.WFS_CAPABILITIES_ROOT1_0_0)==0)) {

                                        version = kxmlParser.getAttributeValue("", CapabilitiesTags.VERSION);

                                }

                        }

                        // do not forget to close the Stream.                    

                        reader.close();                         

                        return version;                

                } catch(ConnectException conEx) {

                        throw new ConnectException(conEx.getMessage());                         

                } catch(IOException ioEx) {

                        throw new IOException(ioEx.getMessage());         

                } catch(XmlPullParserException xmlEx) {

                        String fname = "";

                        if( file != null ) {

                            fname = file.getAbsolutePath();

                        }

                        logger.warn("Can't get suitable WFS version for host '"+host+"' from file '"+fname+"'.",xmlEx);

                        return "";

                } finally {                

                        if (reader != null) {

                                try {

                                        reader.close();

                                } catch(Exception ex) {

                                        logger.warn("Can't close reader.",ex);

                                }

                        }

                } 

        }

        /**

         * Gets the intersection between the versions supported by the server

         * and the versions supported by the application 

         * @throws IOException 

         * @throws ConnectException 

         */

        public static List getRequestableVersions(String host, boolean ignoreCache) throws

        ConnectException, IOException {

            Iterator iVersion = supportedVersions.iterator();

        String wfsVersion;

        String gvSIGVersion;

        ArrayList resp = new ArrayList();

        while (iVersion.hasNext()) { 

            gvSIGVersion = (String)iVersion.next();

            wfsVersion = getSuitableWFSVersion(host,gvSIGVersion, ignoreCache);

            if (gvSIGVersion.compareTo(wfsVersion) == 0) {

                resp.add(gvSIGVersion);

            }

        }

        return resp;

        }

        /**

         * It creates an instance of a WFSDriver class.

         *

         * @param String, with the version of the driver to be created

         * @return WFSDriver.

         */

        public static WFSProtocolHandler createVersionDriver(String version) {               

                try {

                        Class driver;

                        version = version.replace('.', '_');

                        driver = Class.forName("org.gvsig.remoteclient.wfs.wfs_"+version+".WFSProtocolHandler" + version);

                        return (WFSProtocolHandler)driver.newInstance();

                } catch (Exception e) {

                        logger.warn("Can't create driver for WFS version '"+version+"'.",e);

                        return null;

                }

        }    

}