Setting up JDBC Database Connection Pool in Spring framework is easy for any Java application, just matter of changing few configuration in spring configuration file.If you are writing core java application and not running on any web or application server like Tomcat or Weblogic, Managing Database connection pool using Apache Commons DBCP and Commons Pool along-with Spring framework is nice choice but if you have luxury of having web server and managed J2EE Container, consider using Connection pool managed by J2EE server those are better option in terms of maintenance, flexibility and also help to prevent java.lang.OutofMemroyError:PermGen Space in tomcat by avoiding loading of JDBC driver in web-app class-loader, Also keeping JDBC connection pool information in Server makes it easy to change or include settings for JDBC over SSL. In this article we will see how to setup Database connection pool in spring framework using Apache commons DBCP and commons pool.jar
This article is in continuation of my tutorials on spring framework and database like LDAP Authentication in J2EE with Spring Security and manage session using Spring security If you haven’t read those article than you may find them useful.
Spring Example JDBC Database Connection Pool
Spring framework provides convenient JdbcTemplate class for performing all Database related operation. if you are not using Hibernate than using Spring's JdbcTemplate is good option. JdbcTemplate requires a DataSource which is javax.sql.DataSource implementation and you can get this directly using spring bean configuration or by using JNDI if you are using J2EE web server or application server for managing Connection Pool. See How to setup JDBC connection Pool in tomcat and Spring for JNDI based connection pooling for more details. In order to setup Data source you will require following configuration in your applicationContext.xml (spring configuration) file:
Below configuration of DBCP connection pool will create 20 database connection as initialSize is 20 and goes up to 30 Database connection if required as maxActive is 30. you can customize your database connection pool by using different properties provided by Apache DBCP library. Above example is creating connection pool with Oracle 11g database and we are using oracle.jdbc.driver.OracleDriver comes along with ojdbc6.jar or ojdbc6_g.jar , to learn more about how to connect Oracle database from Java program see the link.
Java Code for using Connection pool in Spring
Below is complete code example of DAO class which uses Spring JdbcTemplate to execute SELECT query against database using database connection from Connection pool. If you are not initializing Database connection pool on start-up than it may take a while when you execute your first query because it needs to create certain number of SQL connection and then it execute query but once connection pool is created subsequent queries will execute faster.
1. you need to include oracle driver jar like ojdbc_6.jar in you classpath.
2. Apache DBCP and commons pool jar in application classpath.
That's all on how to configure JDBC Database connection pool in Spring framework. As I said its pretty easy using Apache DBCP library. Just matter of few configuration in spring applicationContext.xml and you are ready. If you want to configure JDBC Connection pool on tomcat (JNDI connection pool) and want to use in spring than see here.
Other Java JDBC tutorials you may like
P.S. - If you are an experienced Java/JEE Program and want to learn Spring Security end-to-end, I recommend Learn Spring Security course by Eugen Paraschiv, The definitive guide to secure your Java application. It's useful for both junior and experienced Java Web developers.
He is also author of REST with Spring course, one of the best online course to learn RESTful WebServices using Spring framework.
P.S - If you like to learn from book, then Spring in Action by Craig Walls is a good starting point. The content is good enough for both junior and senior developers. It's in fact a great book to startwith core spring.