dbconnectiondefaultpool.java

这是学习Java必须读懂两套源代码

/**
 * Copyright (C) 2001 Yasna.com. All rights reserved.
 *
 * ===================================================================
 * The Apache Software License, Version 1.1
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. 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.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by
 *        Yasna.com (http://www.yasna.com)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Yazd" and "Yasna.com" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please
 *    contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Yazd",
 *    nor may "Yazd" appear in their name, without prior written
 *    permission of Yasna.com.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED 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 YASNA.COM OR
 * ITS 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of Yasna.com. For more information
 * on Yasna.com, please see <http://www.yasna.com>.
 */

/**
 * Copyright (C) 2000 CoolServlets.com. All rights reserved.
 *
 * ===================================================================
 * The Apache Software License, Version 1.1
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. 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.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by
 *        CoolServlets.com (http://www.coolservlets.com)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Jive" and "CoolServlets.com" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please
 *    contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Jive",
 *    nor may "Jive" appear in their name, without prior written
 *    permission of CoolServlets.com.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED 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 COOLSERVLETS.COM OR
 * ITS 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of CoolServlets.com. For more information
 * on CoolServlets.com, please see <http://www.coolservlets.com>.
 */

package com.Yasna.forum.database;

import java.sql.*;
import java.util.*;
import java.io.*;
import java.text.*;
import java.util.Date;
import com.Yasna.forum.*;

/**
 * Default Yazd connection provider. It uses the excellent connection pool
 * available from http://www.javaexchange.com. This connection provider is a
 * a good choice unless you can use a container-managed one.
 */
public class DbConnectionDefaultPool extends DbConnectionProvider {

    private static final String NAME = "Default Connection Pool";
    private static final String DESCRIPTION = "The default connection provider "
        + "that uses the connection pool from javaexchange.com. It works with "
        + "almost any database setup, is customizable, and offers good performance. "
        + "Use this connection provider unless you have your own or can use a "
        + "container managed connection pool.";
    private static final String AUTHOR = "Yazd.Yasna.com";
    private static final int MAJOR_VERSION = 1;
    private static final int MINOR_VERSION = 0;
    private static final boolean POOLED = true;

    private ConnectionPool connectionPool = null;
    private Properties props;
    private Properties propDescriptions;

    private Object initLock = new Object();

    public DbConnectionDefaultPool() {
        //this.manager = manager;
        props = new Properties();
        propDescriptions = new Properties();
        //Initialize all property values
        initializeProperties();
        //Load any existing property values
        loadProperties();
    }

    /**
     * Returns a database connection.
     */
    public Connection getConnection() {
        if (connectionPool == null) {
            //block until the init has been done
            synchronized(initLock) {
                //if still null, something has gone wrong
                if (connectionPool == null) {
                    System.err.println("Warning: DbConnectionDefaultPool.getConnection() was " +
                    "called when the internal pool has not been initialized.");
                    return null;
                }
            }
        }
        return new ConnectionWrapper(connectionPool.getConnection(), connectionPool);
    }

    /**
     * Starts the pool.
     */
    protected void start() {
        //acquire lock so that no connections can be returned.
        synchronized (initLock) {
            //Get properties
            String driver = props.getProperty("driver");
            String server = props.getProperty("server");
            String username = props.getProperty("username");
            String password = props.getProperty("password");
            int minConnections = 0, maxConnections = 0;
            double connectionTimeout = 0.0;
            try {
                minConnections = Integer.parseInt(props.getProperty("minConnections"));
                maxConnections = Integer.parseInt(props.getProperty("maxConnections"));
                connectionTimeout = Double.parseDouble(props.getProperty("connectionTimeout"));
            }
            catch (Exception e) {
                System.err.println("Error: could not parse default pool properties. " +
                    "Make sure the values exist and are correct.");
                e.printStackTrace();
                return;
            }
            String logPath = props.getProperty("logPath");

            try {
                connectionPool = new ConnectionPool(driver, server, username, password,
                    minConnections, maxConnections, logPath, connectionTimeout);
            }
            catch (IOException ioe) {
                System.err.println("Error starting DbConnectionDefaultPool: " + ioe);
                ioe.printStackTrace();
            }
        }
    }

    /**
     * Restarts the pool to take into account any property changes.
     */
    protected void restart() {
        //Kill off pool.
        destroy();
        //Reload properties.
        loadProperties();
        //Start a new pool.
        start();
    }

    /**
     * Destroys the connection pool.
     */
    protected void destroy() {
        if (connectionPool != null) {
            try {
                connectionPool.destroy(1);
            }
            catch (Exception e) {
                e.printStackTrace();
            }
        }
        //Release reference to connectionPool
        connectionPool = null;
    }

    /**
     * Returns the value of a property of the connection provider.
     *
     * @param name the name of the property.
     * @returns the value of the property.
     */
    public String getProperty(String name) {
        return (String)props.get(name);
    }

    /**
     * Returns the description of a property of the connection provider.
     *
     * @param name the name of the property.
     * @return the description of the property.
     */
    public String getPropertyDescription(String name) {
        return (String)propDescriptions.get(name);
    }

    /**
     * Returns an enumeration of the property names for the connection provider.
     */
    public Enumeration propertyNames() {
        return props.propertyNames();
    }

    /**
     * Sets a property of the connection provider. Each provider has a set number
     * of properties that are determined by the author. Trying to set a non-
     * existant property will result in an IllegalArgumentException.
     *
     * @param name the name of the property to set.
     * @param value the new value for the property.
     *
     */
    public void setProperty(String name, String value) {
        props.put(name, value);
        saveProperties();
    }

    /**
     * Give default values to all the properties and descriptions.
     */
    private void initializeProperties() {
        props.put("driver","");
        props.put("server","");
        props.put("username","");
        props.put("password","");
        props.put("minConnections","");
        props.put("maxConnections","");
        props.put("logPath","");
        props.put("connectionTimeout","");

        propDescriptions.put("driver","JDBC driver. e.g. 'oracle.jdbc.driver.OracleDriver'");
        propDescriptions.put("server","JDBC connect string. e.g. 'jdbc:oracle:thin:@203.92.21.109:1526:orcl'");
        propDescriptions.put("username","Database username. e.g. 'Scott'");
        propDescriptions.put("password","Database password. e.g. 'Tiger'");
        propDescriptions.put("minConnections","Minimum # of connections to start with in pool. Three is the recommended minimum");
        propDescriptions.put("maxConnections","Maximum # of connections in dynamic pool. Fifteen should give good performance for an average load.");
        propDescriptions.put("logPath","Absolute path name for log file. e.g. 'c:\\logs\\yazdDbLog.log'");
        propDescriptions.put("connectionTimeout","Time in days between connection resets. e.g. '.5'");
    }

    /**
     * Load whatever properties that already exist.
     */
    private void loadProperties() {
        String driver = PropertyManager.getProperty("DbConnectionDefaultPool.driver");
        String server = PropertyManager.getProperty("DbConnectionDefaultPool.server");
        String username = PropertyManager.getProperty("DbConnectionDefaultPool.username");
        String password = PropertyManager.getProperty("DbConnectionDefaultPool.password");
        String minConnections = PropertyManager.getProperty("DbConnectionDefaultPool.minConnections");
        String maxConnections = PropertyManager.getProperty("DbConnectionDefaultPool.maxConnections");
        String logPath = PropertyManager.getProperty("DbConnectionDefaultPool.logPath");
        String connectionTimeout = PropertyManager.getProperty("DbConnectionDefaultPool.connectionTimeout");

        if (driver != null) {  props.setProperty("driver", driver);  }
        if (server != null) {  props.setProperty("server", server);  }
        if (username != null) {  props.setProperty("username", username);  }
        if (password != null) {  props.setProperty("password", password);  }
        if (minConnections != null) {  props.setProperty("minConnections", minConnections);  }
        if (maxConnections != null) {  props.setProperty("maxConnections", maxConnections);  }
        if (logPath != null) {  props.setProperty("logPath", logPath);  }
        if (connectionTimeout != null) {  props.setProperty("connectionTimeout", connectionTimeout);  }
    }

    private void saveProperties() {
        PropertyManager.setProperty("DbConnectionDefaultPool.driver", props.getProperty("driver"));
        PropertyManager.setProperty("DbConnectionDefaultPool.server", props.getProperty("server"));
        PropertyManager.setProperty("DbConnectionDefaultPool.username", props.getProperty("username"));
        PropertyManager.setProperty("DbConnectionDefaultPool.password", props.getProperty("password"));
        PropertyManager.setProperty("DbConnectionDefaultPool.minConnections", props.getProperty("minConnections"));
        PropertyManager.setProperty("DbConnectionDefaultPool.maxConnections", props.getProperty("maxConnections"));
        PropertyManager.setProperty("DbConnectionDefaultPool.logPath", props.getProperty("logPath"));
        PropertyManager.setProperty("DbConnectionDefaultPool.connectionTimeout", props.getProperty("connectionTimeout"));
    }

    /**
     * DbConnectionBroker
     * @version 1.0.11 12/7/99
     * @author Marc A. Mnich
     *
     * ----------------------------------------
     * Modified June 18, 2000 by Matt Tucker
     *   Changes:
     *     - New package name, class name to make it nice to embed as
     *        an internal class.
     *     - Source code reformatting.
     *     - Added more error handling code in constructor, createConn method
     *       so that more information is given to Yazd users.
     * DbConnectionBroker rules! Download it from javaexchange.com
     * ----------------------------------------