connection pooling

[gaser hasan]

please i am new to jsp, when i tried to implement this example of connection pooling it gives me (too many connections) error, and the connection doesn't work
those are the two classes of the example please could any one tell me where is the problem and how to implement the in a right way ?
thanks in advance
////////////////////////////class ConnectionPoo.javal /////////////////////////////////////

  
package com.bean;

/**
 *
 * @author gaser_java
 */
import java.util.*;
import java.sql.*;

public class ConnectionPool implements Runnable
{
    // Number of initial connections to make.
    private int m_InitialConnectionCount = 19;
    // A list of available connections for use.
    private Vector m_AvailableConnections = new Vector();
    // A list of connections being used currently.
    private Vector m_UsedConnections = new Vector();
    // The URL string used to connect to the database
    private String m_URLString = null;
    // The username used to connect to the database
    private String m_UserName = null;
    // The password used to connect to the database
    private String m_Password = null;
    // The cleanup thread
    private Thread m_CleanupThread = null;


    //Constructor
    public ConnectionPool(String urlString, String user, String passwd) throws SQLException
    {
        // Initialize the required parameters
        m_URLString = urlString;
        m_UserName = user;
        m_Password = passwd;

        for(int cnt=0; cnt<m_InitialConnectionCount; cnt++)
        {
            // Add a new connection to the available list.
            m_AvailableConnections.addElement(getConnection());
        }

        // Create the cleanup thread
        m_CleanupThread = new Thread(this);
        m_CleanupThread.start();
    }

    private Connection getConnection() throws SQLException
    {
        return DriverManager.getConnection(m_URLString, m_UserName, m_Password);
    }

    public synchronized Connection checkout() throws SQLException
    {
        Connection newConnxn = null;

        if(m_AvailableConnections.size() == 0)
        {
            // Im out of connections. Create one more.
             newConnxn = getConnection();
            // Add this connection to the "Used" list.
             m_UsedConnections.addElement(newConnxn);
            // We dont have to do anything else since this is
            // a new connection.
        }
        else
        {
            // Connections exist !
            // Get a connection object
            newConnxn = (Connection)m_AvailableConnections.lastElement();
            // Remove it from the available list.
            m_AvailableConnections.removeElement(newConnxn);
            // Add it to the used list.
            m_UsedConnections.addElement(newConnxn);
        }

        // Either way, we should have a connection object now.
        return newConnxn;
    }


    public synchronized void checkin(Connection c)
    {
        if(c != null)
        {
            // Remove from used list.
            m_UsedConnections.removeElement(c);
            // Add to the available list
            m_AvailableConnections.addElement(c);
        }
    }

    public int availableCount()
    {
        return m_AvailableConnections.size();
    }

    public void run()
    {
        try
        {
            while(true)
            {
                synchronized(this)
                {
                    while(m_AvailableConnections.size() > m_InitialConnectionCount)
                    {
                        // Clean up extra available connections.
                        Connection c = (Connection)m_AvailableConnections.lastElement();
                        m_AvailableConnections.removeElement(c);
                        // Close the connection to the database.
                        c.close();
                    }

                    // Clean up is done
                }
                System.out.println("CLEANUP : Available Connections : " + availableCount());

                // Now sleep for 1 minute
                Thread.sleep(60000 * 1);
            }
        }
        catch(SQLException sqle)
        {
            sqle.printStackTrace();
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    }
}

  

///////////////////////////class main.java//////////////////////////////////

    import java.sql.*;

public class Main {

    public String dburl = "jdbc:mysql://localhost:3307/alsa7a1c?useUnicode=true&characterEncoding=utf-8";
    //public String dburl = "jdbc:mysql://localhost/alsa7a1c?useUnicode=true&characterEncoding=utf-8";
    public String dbusername = "root";
    //public String dbusername ="alsa7a1c";
    public String dbuserPassword = "123456";
    // public String dbuserPassword="peduruko";
    public Connection con;
    public PreparedStatement ps;
    public ResultSet rs;
    public  void main() {
        try {
            Class.forName("com.mysql.jdbc.Driver").newInstance();
        } catch (Exception E) {
            System.err.println("Unable to load driver.");
            E.printStackTrace();
        }
        try {
            ConnectionPool cp = new ConnectionPool("jdbc:mysql://localhost:3307/alsa7a1c?useUnicode=true&characterEncoding=utf-8", "root", "123456");
            Connection[] connArr = new Connection[19];
            for (int i = 0; i < connArr.length; i++) {
                connArr[i] = cp.checkout();
                System.out.println("Checking out..." + connArr[i]);
                System.out.println("Available Connections ... " + cp.availableCount());
            }

            for (int i = 0; i < connArr.length; i++) {
                cp.checkin(connArr[i]);
                System.out.println("Checked in..." + connArr[i]);
                System.out.println("Available Connections ... " + cp.availableCount());
            }
        } catch (SQLException sqle) {
            sqle.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

[Jan Cumps]

Please UseCodeTags.
When your post is properly formatted, people will find it easier to read and help you.

[gaser hasan]

thank you Dear Jan Cumps i am sorry i am new to the forum but i promise that i will stick to the instructions

[Jeanne Boyarsky]

Why are you writing your own connection pool? It would bet better to use an open source one that already works such as dbcp or c3p0.

Also, you may want to not use red for your question. It's a bit of an eyestrain on the tan background.

[Jeanne Boyarsky]

And Welcome to JavaRanch!