Application: gvSIG desktop » Library: org.gvsig.tools

/**

 * 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 2

 * 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.

 */

/*

 * AUTHORS (In addition to CIT):

 * 2008 {DiSiD Technologies}   {Create a base Locator implementation}

 */

package org.gvsig.tools.locator;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import org.gvsig.tools.extensionpoint.ExtensionPoint;

import org.gvsig.tools.extensionpoint.ExtensionPointManager;

import org.gvsig.tools.extensionpoint.impl.DefaultExtensionPointManager;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

/**

 * Locator implementation based on the use of the ExtensionPoints.

 *

 * @author <a href="mailto:cordin@disid.com">C?sar Ordi?ana</a>

 */

public abstract class AbstractLocator implements Locator, Locator_withExists {

    private Map      instances  = new HashMap();

    private Logger   logger     = LoggerFactory.getLogger(AbstractLocator.class);

    private Object   lock       = new Object();

    public Object get(String name) throws LocatorException {

        Object instance = null;

        // Synchronize the creation and storage of instances

        synchronized (lock) {

            instance = instances.get(name);

            if (instance == null) {

                try {

                    instance = getExtensionPoint().create(name);

                } catch (Exception ex) {

                    throw new LocatorReferenceException(ex, name, this);

                }

                instances.put(name, instance);

                            logger.info("Stored the instance of " + name + " in the singleton table.");

            }

        }

        return instance;

    }

    public boolean exists(String name) {

        return instances.containsKey(name); 

    }

    private void removeFromInstances(String name) {

            synchronized (lock) {

                    if(instances.containsKey(name)) {

                            logger.info("Removing the instance of " + name + " from the singleton table.");

                            instances.remove(name);

                    }

            }

    }

    public String[] getNames() {

        ExtensionPoint extensionPoint = getExtensionPoint();

        List names = extensionPoint.getNames();

        return names == null || names.size() == 0 ? null

                : (String[]) names

                .toArray(new String[names.size()]);

    }

    public void register(String name, Class clazz) {

            DefaultExtensionPointManager.getManager().add(getLocatorName())

                                .append(name, null, clazz);

            removeFromInstances(name);

    }

    public void registerDefault(String name, Class clazz) {

                ExtensionPoint ep = getExtensionPoint();

                if (ep.get(name) == null) {

                        register(name, clazz);

                }

        }

    public void register(String name, String description, Class clazz) {

            DefaultExtensionPointManager.getManager().add(getLocatorName())

                                .append(name,

                description, clazz);

            removeFromInstances(name);

    }

    public void registerDefault(String name, String description, Class clazz) {

            ExtensionPoint ep = getExtensionPoint();

            if( ep.get(name) == null ) {

                    register(name,description, clazz);

                    removeFromInstances(name);

            }

    }

    public void register(String name, LocatorObjectFactory factory) {

            DefaultExtensionPointManager.getManager().add(getLocatorName()).append(

                                name, null,

                factory);

            removeFromInstances(name);

    }

    public void register(String name, String description,

            LocatorObjectFactory factory) {

            DefaultExtensionPointManager.getManager().add(getLocatorName()).append(

                                name,

                description, factory);

            removeFromInstances(name);

    }

    public String toString() {

        return getLocatorName();

    }

    /**

     * Returns the ExtensionPoint to use for the Locator values.

     */

    private ExtensionPoint getExtensionPoint() {

        ExtensionPointManager manager = DefaultExtensionPointManager

                                .getManager();

        String moduleName = getLocatorName();

        // synchronize the retrieval of the ExtensionPoint

        synchronized (lock) {

            ExtensionPoint extensionPoint = manager.get(moduleName);

            if (extensionPoint == null) {

                extensionPoint = manager.add(moduleName);

            }

            return extensionPoint;

        }

    }

}