Application: gvSIG desktop

/* gvSIG. Geographic Information System of the Valencian Government

*

* Copyright (C) 2007-2008 Infrastructures and Transports Department

* of the Valencian Government (CIT)

*

* 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.

*

*/

/*

* AUTHORS (In addition to CIT):

* 2009 IVER T.I   {{Task}}

*/

package org.gvsig.fmap.dal.resource.db;

import org.gvsig.fmap.dal.exception.DataException;

import org.gvsig.fmap.dal.exception.InitializeException;

import org.gvsig.fmap.dal.resource.ResourceParameters;

import org.gvsig.fmap.dal.resource.exception.AccessResourceException;

import org.gvsig.fmap.dal.resource.exception.ResourceException;

import org.gvsig.fmap.dal.resource.spi.AbstractResource;

/**

 * Abstract Data Base Resource implementation that prevents the concurrent

 * access.

 *

 * @author jmvivo

 * 

 */

public abstract class AbstractDBResourceBlocker extends AbstractResource

                implements

                DBResource {

        /**

         * Default constructor

         *

         * @param parameters

         * @throws InitializeException

         */

        protected AbstractDBResourceBlocker(DBResourceParameters parameters)

                        throws InitializeException {

                super(parameters);

        }

        /**

         * Return a connection to the data base.<br>

         * Connect to the Data Base if is needed

         *

         * @return connection to the data base

         */

        public Object get() throws AccessResourceException {

                if (!isConnected()) {

                        try {

                                this.connect();

                        } catch (DataException e) {

                                throw new AccessResourceException(this, e);

                        }

                }

                try {

                        return getTheConnection();

                } catch (DataException e) {

                        throw new AccessResourceException(this, e);

                }

        }

        /**

         * Return a connection to the data base.<br>

         * Connect to the Data Base if is needed

         *

         *

         * @return connection to the data base

         * @see #get()

         */

        public Object getConnection() throws AccessResourceException {

                return get();

        }

        /**

         * Establish connection to data base

         *

         * @throws DataException

         */

        public final void connect() throws DataException {

                if (this.isConnected()) {

                        return;

                }

                prepare();

                connectToDB();

        }

        /**

         * Check if parameters is the same for this resource.<br>

         * <br>

         *

         * <strong>Note:</strong> override this method to add checks for specify

         * final implementation parameters

         *

         *

         * @see AbstractResource#isThis(ResourceParameters)

         */

        public boolean isThis(ResourceParameters parameters)

                        throws ResourceException {

                if (!(parameters instanceof DBResourceParameters)) {

                        return false;

                }

                DBResourceParameters params = (DBResourceParameters) parameters

                                .getCopy();

                prepare(params);

                DBResourceParameters myParams = (DBResourceParameters) this

                                .getParameters();

                if (!equals(myParams.getHost(), params.getHost())) {

                        return false;

                }

                if (!equals(myParams.getPort(), params.getPort())) {

                        return false;

                }

                if (!equals(myParams.getUser(), params.getUser())) {

                        return false;

                }

                return true;

        }

        @SuppressWarnings("unchecked")

        protected boolean equals(Comparable v1, Comparable v2) {

                if (v1 == v2) {

                        return true;

                }

                if ((v1 != null) && (v2 != null)) {

                        return v1.compareTo(v2) == 0;

                }

                return false;

        }

        /**

         * final implementation method to Establish connection to data base<br>

         * Called from {@link #get()}<br>

         * <br>

         *

         *

         * @throws DataException

         */

        protected abstract void connectToDB() throws DataException;

        /**

         * final implementation method to get a connection to data base<br>

         * Called from {@link #connect()}<br>

         * <br>

         * This method is called with the connection establish

         *

         * @throws DataException

         */

        protected abstract Object getTheConnection() throws DataException;

}