SimplePool/src/net/java/dev/simplepool/SimplePoolServlet.java

/*
 * $Source: /home/cvsroot/manywhere/simplepool/src/net/java/dev/simplepool/SimplePoolServlet.java,v $
 * $Revision: 1.5 $
 * $Date: 2004/03/17 23:35:36 $
 *
 * Copyright (c) 2004, Russell Beattie (http://www.russellbeattie.com/)
 * All rights reserved.
 *
 * Copyright (c) 2004, Erik C. Thauvin (http://www.thauvin.net/erik/)
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the authors nor the names of its contributors may be
 * used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package net.java.dev.simplepool;

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

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;


/**
 * Creates a pool of database connection based on the specific intialization parameters.
 *
 * @author <a href="http://www.russellbeattie.com/">Russell Beattie</a>
 * @author <a href="http://www.thauvin.net/erik/">Erik C. Thauvin</a>
 * @version $Revision: 1.5 $, $Date: 2004/03/17 23:35:36 $
 * @since 1.0
 */
public class SimplePoolServlet extends HttpServlet {

    private static final Log log = LogFactory.getLog(SimplePoolServlet.class);
    private static SimplePoolDataSource dataSource;

    /**
     * Closes the connection pool.
     *
     * @see javax.servlet.http.HttpServlet#destroy
     */
    public void destroy() {
        if (dataSource != null) {
            dataSource.close();
        }
    }

    /**
     * Initializes the connection pool.
     * <p/>
     * The required intialization parameters are:
     * <p/>
     * <ul>
     * <li><code>varName</code> &ndash; Name of the variable used to hold a reference to the
     * {@link SimplePoolDataSource}.</li>
     * <li><code>driver</code> &ndash; JDBC driver. e.g. 'oracle.jdbc.driver.OracleDriver'</li>
     * <li><code>jdbcUrl</code> &ndash; JDBC connect string. e.g. 'jdbc:oracle:thin:@203.92.21.109:1526:orcl'</li>
     * <li><code>user</code> &ndash; Database login name. e.g. 'Scott'</li>
     * <li><code>password</code> &ndash; Database password. e.g. 'Tiger'</li>
     * <li><code>minConns</code> &ndash; Minimum number of connections to start with.</li>
     * <li><code>maxConns</code> &ndash; Maximum number of connections in dynamic pool.</li>
     * <li><code>maxConnTime</code> &ndash; Time in days between connection resets.</li>
     * <li><code>maxCheckoutSeconds</code> &ndash; Max time a connection can be checked out before being recycled.</li>
     * </ul>
     *
     * @see javax.servlet.http.HttpServlet#init(ServletConfig)
     */
    public void init(ServletConfig servletConfig)
            throws ServletException {
        log.info("Initializing " + servletConfig.getServletName() + " Servlet");

        String varName = servletConfig.getInitParameter("varName");
        String driver = servletConfig.getInitParameter("driver");
        String jdbcUrl = servletConfig.getInitParameter("jdbcUrl");
        String user = servletConfig.getInitParameter("user");
        String password = servletConfig.getInitParameter("password");
        String minConns = servletConfig.getInitParameter("minConns");
        String maxConns = servletConfig.getInitParameter("maxConns");
        String maxConnTime = servletConfig.getInitParameter("maxConnTime");
        String maxCheckoutSeconds = servletConfig.getInitParameter("maxCheckoutSeconds");

        if (isValid(varName) && isValid(driver) && isValid(jdbcUrl) && (user != null) && (password != null)
                && isValid(minConns) && isValid(maxConns) && isValid(maxConnTime) && isValid(maxCheckoutSeconds)) {
            dataSource = new SimplePoolDataSource();

            dataSource.setDriver(driver);
            dataSource.setJdbcUrl(jdbcUrl);
            dataSource.setUser(user);
            dataSource.setPassword(password);
            dataSource.setMinConns(minConns);
            dataSource.setMaxConns(maxConns);
            dataSource.setMaxConnTime(maxConnTime);
            dataSource.setMaxCheckoutSeconds(maxCheckoutSeconds);

            try {
                dataSource.init();

                servletConfig.getServletContext().setAttribute(varName, dataSource);
            } catch (Exception e) {
                log.error("An error occurred while starting the connection pool.", e);
                throw new ServletException("Error starting the connection pool.");
            }
        } else {
            log.error("One or more intialization parameter is invalid or missing.");
            throw new ServletException("Invalid or missing initialization parameter.");
        }
    }

    private boolean isValid(String s) {
        if ((s != null) && (s.length() > 0)) {
            return true;
        }

        return false;
    }
}