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Tags/Keywords : Apache DBCP, DBCP Pool, DBCP connection, Example,Apache, Code, Tutorial, Article
Author : ISHTEK
Date (Year/Month/Date): 2009-06-30
Tags : Apache DBCP, DBCP Pool, DBCP connection

Tag : Apache DBCP, DBCP Pool, DBCP connection
This example tries to show a simple to understand way of
using Apache DBCP framework to easily setup a connection
Pool for use in web servers, application servers, and
command line based applications on Java Platform.

I shall be showing a test client program only. This Java
program has a simple to use step by step code for setting
up Apache DBCP for managing Pool of database connections.
Apache DBCP uses , Apache Commons Pool utility as well.
So you require both zipped files, one from Apache DBCP
and the other from Apache Commons Pool.



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Software Environment for this Example, I have used as:
1. JDK 5.0
2. Eclipse 3.2
3. HSQLDB 1.7.0
4. Apache Commons DBCP version 1.2.2
5. Apache Commons Pool version 1.5.1

DBConnectionPool.java

package example.db.pool;

import org.apache.commons.dbcp.DriverManagerConnectionFactory;
import org.apache.commons.dbcp.PoolableConnection;
import org.apache.commons.dbcp.PoolableConnectionFactory;
import org.apache.commons.pool.ObjectPool;
import org.apache.commons.pool.impl.StackKeyedObjectPoolFactory;
import org.apache.commons.pool.impl.StackObjectPoolFactory;

public class DBConnectionPool {

  public DBConnectionPool() {
    try {
      // These two lines marked in red are something database
      //specific configuration for JDBC driver and connection string
      //along with db user name and password.
      Class.forName("org.hsqldb.jdbcDriver");

      //Driver manager connectionfactory is choosen for
      //making this program run as command line program
      //without spending time on setting up datasource specific efforts.
      DriverManagerConnectionFactory drvMgrConnFactory =
                  new DriverManagerConnectionFactory
                              ("jdbc:hsqldb:hsql://localhost/","sa","");
      //This pool factory is used for creating Pool for
      //all poolable connections and to be used by PoolableConnectionFactory.
      // Initial size/capacity for 10 connections only.
      StackObjectPoolFactory stackObjectPoolFactory =
                                      new StackObjectPoolFactory(10,10);
      ObjectPool objectPool = stackObjectPoolFactory.createPool();
      //This pool factory tobe used for pooling
      //preparedstatements, and to be used by PoolableConnectionFactory.
      StackKeyedObjectPoolFactory sKeyObjPoolFactory =
                                 new StackKeyedObjectPoolFactory(10,10);
      //PoolableConnectionFactory for managing all Poolable
      //connections, those are borrowed from it.
      PoolableConnectionFactory poolableConnFactory =
             new PoolableConnectionFactory(drvMgrConnFactory,objectPool,
                                    sKeyObjPoolFactory, null,true,true);

      //Test is to iterate for 20 times and create
      //as many as 20 poolable connections and then return those
      //to the Pool.
      for(int i=0;i<20;i++) {
       PoolableConnection conn =
       (PoolableConnection) poolableConnFactory.getPool().borrowObject();
       System.out.println("Before return :"
     			      +poolableConnFactory.getPool().getNumActive());
       poolableConnFactory.getPool().returnObject(conn);
       System.out.println("After return :"
                      +poolableConnFactory.getPool().getNumActive());
      }
    } catch (Exception ex) {
       ex.printStackTrace();
    }
  }
  public static void main(String[] args) {
    new DBConnectionPool();
  }

}




By checking number of active connections in Pool, it will be clear that
when a poolable connection is borrowed, then total active connection
is 1 and then after returning that to the pool, number of active
connection becomes 0.

If anybody has any question or any better way of doing it,
please share.



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while working with the example code environment setting up, running
and resolving any such exception raised during compile or at runtime.
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