uk.co.modularaudio.util.pooling.sql.ConnectionFactory.java Source code

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Here is the source code for uk.co.modularaudio.util.pooling.sql.ConnectionFactory.java

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/**
 *
 * Copyright (C) 2015 - Daniel Hams, Modular Audio Limited
 *                      daniel.hams@gmail.com
 *
 * Mad 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.
 *
 * Mad 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 Mad.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

package uk.co.modularaudio.util.pooling.sql;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import uk.co.modularaudio.util.pooling.common.Factory;
import uk.co.modularaudio.util.pooling.common.FactoryProductionException;
import uk.co.modularaudio.util.pooling.common.Resource;

/**
 * <P>
 * A Resource Factory that creates database connections matching the supplied
 * arguements.
 * <P>
 *
 * @author D.Hams
 * @see FactoryProductionException
 * @see DatabaseConnectionResource
 */
public class ConnectionFactory implements Factory {
    protected static Log log = LogFactory.getLog(ConnectionFactory.class.getName());

    /**
     * <P>
     * Setup the factory parameters.
     * </P>
     *
     * @param classname
     * @param connectionUrl
     * @param username
     * @param password
     */
    public ConnectionFactory(final String classname, final String connectionUrl, final String username,
            final String password) {
        this.classname = classname;
        this.connectionURL = connectionUrl;
        this.username = username;
        this.password = password;
    }

    /**
     * <P>
     * Create a database connection resource using the configured parameters.
     * </P>
     * <P>
     * A FactoryProductionException is thrown if any problems occur.
     * </P>
     *
     * @exception FactoryProductionException
     */
    @Override
    public Resource createResource() throws FactoryProductionException {
        Resource res = null;
        try {
            // log.debug("About to ask to create a database connection.");
            res = createDBConnection();
            // log.debug("Just created a database connection.");
        } catch (final SQLException sqle) {
            if (log.isErrorEnabled()) {
                log.error("Error creating DBConnection inside factory.");
                log.error("SQLE: " + sqle.toString());
            }
            throw new FactoryProductionException(sqle.toString());
        }
        if (res == null) {
            log.error("Passing back (for some reason) a null resource from the factory.");
        }
        return (res);
    }

    /**
     * <P>
     * Internal method to create the java.sql.Connection, and place it inside a
     * DatabaseConnectionResource.
     * </P>
     *
     * @return DatabaseConnectionResource
     * @exception SQLException
     */
    private DatabaseConnectionResource createDBConnection() throws SQLException {
        // Create the connection
        final Connection c = getConnection();

        // Force the application to explicitly set its commit points.
        c.setAutoCommit(false);

        String setupFunctionIndexes = "ALTER SESSION SET OPTIMIZER_MODE = FIRST_ROWS";
        final PreparedStatement som = c.prepareStatement(setupFunctionIndexes);
        som.execute();
        som.close();

        setupFunctionIndexes = "ALTER SESSION SET QUERY_REWRITE_ENABLED = TRUE";
        final PreparedStatement sqre = c.prepareStatement(setupFunctionIndexes);
        sqre.execute();
        sqre.close();

        setupFunctionIndexes = "ALTER SESSION SET QUERY_REWRITE_INTEGRITY = TRUSTED";
        final PreparedStatement sqri = c.prepareStatement(setupFunctionIndexes);
        sqri.execute();
        sqri.close();

        // log.debug("Altered session to use function indexes.");

        final DatabaseConnectionResource dbcr = new DatabaseConnectionResource(c);
        return (dbcr);
    }

    /**
     * <P>
     * Ask the JDBC driver manager to get a connection to the database.
     * </P>
     *
     * @exception SQLException
     * @return java.sql.Connection
     */
    private Connection getConnection() throws SQLException {
        // log.debug("About to getConnection of '" + connectionURL + "' (" +
        // username + " -> " + password + ")");
        final Connection c = DriverManager.getConnection(connectionURL, username, password);
        // log.debug("Successful in obtaining a connection.");
        return (c);
    }

    /**
     * <P>
     * Initialise the factory by attempting to get the classes required for the
     * driver.
     * </P>
     *
     * @exception FactoryProductionException
     */
    @Override
    public void init() throws FactoryProductionException {
        if (classname == null || classname.equals("")) {
            throw new FactoryProductionException("No driver class specified.");
        }

        try {
            Class.forName(classname);
            // Test creating a connection
            final Connection c = getConnection();
            c.close();
        } catch (final ClassNotFoundException cnfe) {
            throw new FactoryProductionException(cnfe.toString());
        } catch (final SQLException sqle) {
            throw new FactoryProductionException(sqle.toString());
        }
    }

    private String classname = "";
    private String connectionURL = "";
    private String username = "";
    private String password = "";
}