ConnectionPool.java
package com;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Vector;
public class ConnectionPool implements Runnable
{
// Number of initial connections to make.
private int m_InitialConnectionCount = 5;
// A list of available connections for use.
@SuppressWarnings("rawtypes")
private Vector m_AvailableConnections = new Vector();
// A list of connections being used currently.
@SuppressWarnings("rawtypes")
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
@SuppressWarnings("unchecked")
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);
}
@SuppressWarnings("unchecked")
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;
}
@SuppressWarnings("unchecked")
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();
}
}
}
Main.java
package com;
import java.sql.*;
public class Main
{
public static void main (String[] args)
{
try
{
//JDBC Driver for MySql Database
// Class.forName("com.mysql.jdbc.Driver").newInstance();
//JDBC Driver for Oracle Database
Class.forName("oracle.jdbc.OracleDriver");
}
catch (Exception E)
{
System.err.println("Unable to load driver.");
E.printStackTrace();
}
try
{
//Connection with MySQL Database....
//ConnectionPool cp = new ConnectionPool("jdbc:mysql://localhost/test", "root", "vinay0809");
//Connection with Oracle Database...
ConnectionPool cp = new ConnectionPool("jdbc:oracle:thin:@localhost:1521:XE", "java", "vinay0809");
Connection []connArr = new Connection[7];
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();
}
}
}
/**
* @(#)DBConnect.java
* @author
* @version 1.00 2011/5/10
*/
import java.sql.*;
public class DBConnect
{
static Connection con=null;
static final String DBDriver="sun.jdbc.odbc.JdbcOdbcDriver";
static final String DBURL="jdbc:odbc:";
static final String DBName="JAVA";
static final String DBUser="";
static final String DBPassword="";
public Connection getConnection()
{
if(con !=null)
return con;
try
{
con=DriverManager.getConnection("jdbc:odbc:DB2DSN");
}
catch(SQLException e)
{
System.err.println("Cannot connect to database: for DB2. \n Check that DB2 is running and \nthe SKICLUB database Exists.");
}
return con;
}
/**
*main method
*@pram not used
*/
public static void main (String[] args)
{
DBConnect dbdemo=new DBConnect();
System.out.println("Getting Database Driver.");
try
{
Class.forName(DBDriver);
}
catch(ClassNotFoundException e)
{
System.err.println("Cannot load Database Driver:\n for DB2, your classpath muct include\nSQLLIB\\java12\\DB2Java.Zip.");
}
System.out.println("Getting Database Connection");
Connection con=dbdemo.getConnection();
if(con==null)
System.exit(0);
System.out.println("\nDatabase Ready.");
try
{
DatabaseMetaData md=con.getMetaData();
System.out.println("\nProduct Name: "+md.getDatabaseProductName());
System.out.println("\nDriver Name: "+md.getDriverName());
con.close();
}
catch(Exception e)
{
System.err.println(e.getClass().getName()+":"+e.getMessage());
}
}
}
