utility.ConnectionPool.java Source code

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Here is the source code for utility.ConnectionPool.java

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/* Dashboard Builder.
   Copyright (C) 2016 DISIT Lab http://www.disit.org - University of Florence
    
   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. */

//this class provides a database connection pool, using org.apache.commons.dbcp and org.apache.commons.pool libraries
package utility;

import java.io.IOException;
import java.sql.Connection;
import java.util.Properties;
import org.apache.commons.dbcp.ConnectionFactory;
import org.apache.commons.dbcp.DriverManagerConnectionFactory;
import org.apache.commons.dbcp.PoolableConnectionFactory;
import org.apache.commons.dbcp.PoolingDataSource;
import org.apache.commons.pool.impl.GenericObjectPool;
import javax.sql.DataSource;

/**
 *
 * @author Daniele Cenni, daniele.cenni@unifi.it
 */
public class ConnectionPool {

    /**
     *
     */
    public static final String DRIVER = "com.mysql.jdbc.Driver";

    /**
     *
     */
    public String URL;

    /**
     *
     */
    public String USERNAME;

    /**
     *
     */
    public String PASSWORD;

    /**
     *
     */
    public int connections;

    private GenericObjectPool connectionPool = null;

    private static ConnectionPool connPool;
    private static DataSource dataSource;

    /**
     *
     * @param url
     * @param username
     * @param password
     * @throws IOException
     */
    public ConnectionPool(String url, String username, String password, int maxConnections) throws IOException {
        URL = url;
        USERNAME = username;
        PASSWORD = password;
        connections = maxConnections;
    }

    /**
     *
     * @return @throws Exception
     */
    public DataSource setUp() throws Exception {
        /**
         * Load JDBC Driver class.
         */
        Class.forName(ConnectionPool.DRIVER).newInstance();

        /**
         * Creates an instance of GenericObjectPool that holds our pool of
         * connections object.
         */
        connectionPool = new GenericObjectPool();
        // set the max number of connections
        connectionPool.setMaxActive(connections);
        // if the pool is exhausted (i.e., the maximum number of active objects has been reached), the borrowObject() method should simply create a new object anyway
        connectionPool.setWhenExhaustedAction(GenericObjectPool.WHEN_EXHAUSTED_GROW);

        /**
         * Creates a connection factory object which will be use by the pool to
         * create the connection object. We passes the JDBC url info, username and
         * password.
         */
        ConnectionFactory cf = new DriverManagerConnectionFactory(URL, USERNAME, PASSWORD);

        /**
         * Creates a PoolableConnectionFactory that will wraps the connection object
         * created by the ConnectionFactory to add object pooling functionality.
         */
        PoolableConnectionFactory pcf = new PoolableConnectionFactory(cf, connectionPool, null, null, false, true);
        return new PoolingDataSource(connectionPool);
    }

    /**
     *
     * @return
     */
    public GenericObjectPool getConnectionPool() {
        return connectionPool;
    }

    // Prints connection pool status
    public void printStatus() {
        System.out.println("Max   : " + getConnectionPool().getMaxActive() + "; " + "Active: "
                + getConnectionPool().getNumActive() + "; " + "Idle  : " + getConnectionPool().getNumIdle());
    }

    public static Connection getConnection() {
        try {
            if (connPool == null) {
                Configuration conf = Configuration.getInstance();
                connPool = new ConnectionPool(conf.get("urlMySqlDB", "") + conf.get("dbMySql", "ServiceMap"),
                        conf.get("userMySql", ""), conf.get("passMySql", ""),
                        Integer.parseInt(conf.get("maxConnectionsMySql", "10")));
                if (dataSource == null) {
                    dataSource = connPool.setUp();
                }
            }
            return dataSource.getConnection();
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
}