private String getCurrentLocation() {

        String location = getProperty(PROP_DERBY_LOCATION);

        if (location == null) {

            location = ""; // NOI18N

        }

        return location;

    }

/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.

 *

 * Copyright 1997-2010 Sun Microsystems, Inc. All rights reserved.

 *

 * The contents of this file are subject to the terms of either the GNU

 * General Public License Version 2 only ("GPL") or the Common

 * Development and Distribution License("CDDL") (collectively, the

 * "License"). You may not use this file except in compliance with the

 * License. You can obtain a copy of the License at

 * http://www.netbeans.org/cddl-gplv2.html

 * or nbbuild/licenses/CDDL-GPL-2-CP. See the License for the

 * specific language governing permissions and limitations under the

 * License.  When distributing the software, include this License Header

 * Notice in each file and include the License file at

 * nbbuild/licenses/CDDL-GPL-2-CP.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the GPL Version 2 section of the License file that

 * accompanied this code. If applicable, add the following below the

 * License Header, with the fields enclosed by brackets [] replaced by

 * your own identifying information:

 * "Portions Copyrighted [year] [name of copyright owner]"

 *

 * Contributor(s):

 *

 * The Original Software is NetBeans. The Initial Developer of the Original

 * Software is Sun Microsystems, Inc. Portions Copyright 1997-2010 Sun

 * Microsystems, Inc. All Rights Reserved.

 *

 * If you wish your version of this file to be governed by only the CDDL

 * or only the GPL Version 2, indicate your decision by adding

 * "[Contributor] elects to include this software in this distribution

 * under the [CDDL or GPL Version 2] license." If you do not indicate a

 * single choice of license, a recipient has the option to distribute

 * your version of this file under either the CDDL, the GPL Version 2 or

 * to extend the choice of license to its licensees as provided above.

 * However, if you add GPL Version 2 code and therefore, elected the GPL

 * Version 2 license, then the option applies only if the new code is

 * made subject to such option by the copyright holder.

 */

package org.netbeans.modules.derby;

import java.io.File;

import java.io.IOException;

import java.util.logging.Level;

import java.util.logging.Logger;

import org.openide.filesystems.FileObject;

import org.openide.filesystems.FileUtil;

/**

 * Registers installation of JavaDB by creating instance file in cluster config

 * directory. Designed to be called from installer.

 * The DerbyRegistration can called multiple times but only the first invocation

 * is stored.

 * <p>

 * Sample command line<br>

 *

 * java -cp platform/core/core.jar:platform/lib/boot.jar:platform/lib/org-openide-modules.jar:

 *          platform/core/org-openide-filesystems.jar:platform/lib/org-openide-util.jar:

 *          platform/lib/org-openide-util-lookup.jar:ide/modules/org-netbeans-modules-derby.jar

 *             org.netbeans.modules.derby.DerbyRegistration nb /usr/local/share/java/jdk1.6.0_18/db

 *

 * @author Jiri Rechtacek

 * @see #main(args)

 */

public class DerbyRegistration {

    private static final String DERBY_REGISTRATION_DIR = "JavaDB"; // NOI18N

    private static final String DERBY_REGISTRATION_FILE = "registration_instance"; // NOI18N

    private static final String ATTR_DERBY_HOME = "javadb_installation_home"; // NOI18N

    private static final Logger LOGGER = Logger.getLogger(DerbyRegistration.class.getName());

    /**

     * Performs registration.

     *

     * Exit codes:<p>

     * <ul>

     *   <li> 2: could not find/create config/JavaDB folder

     *   <li> 3: could not find JavaDB installation home

     *   <li> 4: JavaDB installation doesn't contain expected libraries, i.e. lib/derbyclient.jar

     *   <li> 5: could not write registration FileObject

     * </ul>

     * @param args command line arguments - cluster path and Derby home expected

     */

    public static void main(String[] args) throws IOException {

        if (args.length < 2) {

            System.out.println("Parameters: <nb clusterDir> <Derby home>");

            System.exit(-1);

        }

        int status = registerDerbyInstallation(args[0], args[1]);

        System.exit(status);

    }

    private static int registerDerbyInstallation(String cluster, String derbyHome) throws IOException {

        LOGGER.log(Level.FINE, "Cluster for JavaDB registration is " + cluster);

        System.setProperty("netbeans.user", cluster); // NOI18N

        // check writable cluster

        FileObject javaDBRegistrationDir = FileUtil.getConfigFile(DERBY_REGISTRATION_DIR);

        if (javaDBRegistrationDir == null) {

            javaDBRegistrationDir = FileUtil.createFolder(FileUtil.getConfigRoot(), DERBY_REGISTRATION_DIR);

            if (javaDBRegistrationDir == null) {

                LOGGER.log(Level.INFO, "Cannot register the default JavaDB. The config/" + DERBY_REGISTRATION_DIR + " folder cannot be created."); // NOI18N

                return 2;

            }

        }

        // check if exists

        File derbyHomeFile = new File(derbyHome);

        if (!derbyHomeFile.exists()) {

            LOGGER.log(Level.INFO, "Cannot register the default JavaDB. " // NOI18N

                    + "The JavaDB installation directory " + derbyHome // NOI18N

                    + " does not exist."); // NOI18N

            return 3;

        }

        // check if solid JavaDB home

        if (! Util.isDerbyInstallLocation(derbyHomeFile)) {

            LOGGER.log(Level.INFO, "Cannot register the default JavaDB. " // NOI18N

                    + "The JavaDB installation directory " + derbyHome // NOI18N

                    + " does not contain expected libraries."); // NOI18N

            return 4;

        }

        FileObject registrationFO = FileUtil.getConfigFile(DERBY_REGISTRATION_DIR + "/" + DERBY_REGISTRATION_FILE); // NOI18N

        if (registrationFO == null) {

            try {

                registrationFO = javaDBRegistrationDir.createData(DERBY_REGISTRATION_FILE);

                registrationFO.setAttribute(ATTR_DERBY_HOME, derbyHome);

                LOGGER.log(Level.FINE, "New registration links to " + registrationFO.getAttribute(ATTR_DERBY_HOME)); // NOI18N

            } catch (IOException e) {

                LOGGER.log(Level.INFO, "Cannot register JavaDB, cause " + e.getLocalizedMessage(), e); // NOI18N

                return 5;

            }

        } else {

            LOGGER.log(Level.INFO, "The previous registration found. Links to " + registrationFO.getAttribute(ATTR_DERBY_HOME)); // NOI18N

        }

        return 0;

    }

    public static String getRegisteredDerbyHome () {

        FileObject registrationFO = FileUtil.getConfigFile(DERBY_REGISTRATION_DIR + "/" + DERBY_REGISTRATION_FILE); // NOI18N

        String home = (String) (registrationFO == null ? null : registrationFO.getAttribute(ATTR_DERBY_HOME));

        LOGGER.log(Level.FINE, "Registered home is " + home);

        return home;

    }

}

        // find in registration by NBI

        String derbyHome = DerbyRegistration.getRegisteredDerbyHome();

        if (derbyHome != null) {

            LOGGER.log(Level.FINE, "Registered JavaDB:  " + derbyHome);

            File derbyHomeFile = new File(derbyHome);

            String result = testDerbyInstallLocation(derbyHomeFile);

            if (result != null) {

                return result;

            }

        }

        // find in JDK

        if (location == null || ! location.exists()) {

            return false;

        }