How to setup JNDI Database Connection pool in Tomcat - Spring Tutorial Example

Setting the JNDI Database Connection pool in Spring and Tomcat is pretty easy. Tomcat server documentation gives enough information on how to set up a connection pool in Tomcat 5, 6, 7, 8, or 9. Here we will use Tomcat 7 along with the spring framework for creating a connection pool in the Tomcat server and accessing them in Spring using JNDI code. In our last article, we have seen how to set up a database connection pool in Spring for a core Java application that doesn't run on a web server or application server and doesn't have a managed Java EE container.

If you are developing a web application then it's better to use server managed connection pool and access them using JNDI. Spring configuration will be generic and just based on the JNDI name of Datasource so it will work on any J2EE Server e.g. Glassfish, WebLogic, JBoss, or WebSphere until the JNDI name is the same. 

Btw, Tomcat is my favorite web server and I use it a lot on development as it comes integrated with IDE like Eclipse and Netbeans. I am using it for all test and development purposes, and many companies even run Tomcat in Production for hosting Java web applications. 

It's simple, fast, and very robust, though beware with java.lang.OutOfMemoryError: PermGen space in tomcat, which can cause a memory leak in Java application. It usually happens due to ThreadLocal variables and JDBC drivers but you can surely avoid that by knowing more

How to use JNDI database connection pool in Tomcat and Spring

These three steps to configure and run a JNDI Datasource Connection pool for any  Java Web application:

1) Configure data source in Server and create JNDI name.

2) Configure web.xml

3) Configure Spring bean with JNDI Datasource

4) Include JDBC driver library on Server lib e.g. tomcat/lib

In order to create JNDI DataSource on the J2EE web server, you need to follow server documentation. On Tomcat 6 you can simply put the following piece of XML in context.xml to create Tomcat managed database connection pool:

<?xml version="1.0" encoding="UTF-8"?>
<Context antiJARLocking="true" path="/springDataSourceDemo">
<Resource name="jdbc/springeDataSource"
         auth="Container"
         type="javax.sql.DataSource"
         driverClassName="oracle.jdbc.driver.OracleDriver"
         url="jdbc:oracle:thin:@localhost:1521:SPRING_TEST"
         username="root"
         password="root"
         removeAbandoned="true"
         removeAbandonedTimeout="90"
         logAbandoned="true"
         maxActive="20"
         maxIdle="10"
         maxWait="-1"/>
</Context>

Resource element will create a JNDI data source that can be referenced using JNDI name "jdbc/springeDataSource". 

Tomcat internally uses the DBCP and Commons pool library for managing the database connection pool. You can check the tomcat/lib directory for jar file tomcat-dbcp.jar which is responsible for creating a database connection pool inside the tomcat server.

1. web.xml configuration to access JNDI Database connection pool

In order to access any server resource from your web application, you need to specify the JNDI resources in web.xml. 

You can use the following XML to declare JNDI Datasource in web.xml:

 <resource-ref>
        <description>Oracle Spring JNDI Datasource</description>
        <res-ref-name>jdbc/springDataSource</res-ref-name>
        <res-type>javax.sql.DataSource</res-type>
        <res-auth>Container</res-auth>
</resource-ref>

Now your web application will see JNDI Datasource created in tomcat with the name jdbc/springDataSource. 

2. Spring configuration for accessing JNDI Datasource :

This spring configuration is generic enough which can be used to access any JNDI data source deployed on any J2EE or Java EE Server. It’s not tied up with Tomcat.  The org.springframework.jndi.JndiObjectFactoryBean is used to lookup JNDI Datasource and bind with javax.sql.DataSource.

<bean id="springDataSource" class="org.springframework.jndi.JndiObjectFactoryBean">
  <property name="jndiName" value="java:comp/env/jdbc/springDataSource"/>
  <property name="lookupOnStartup" value="true"/>
  <property name="proxyInterface" value="javax.sql.DataSource"/>
</bean>

I have used XML way to declare a spring bean here, but, If you are using Spring 3.0 or higher than you can also use Java Configuration and @Bean annotation to declare data source in a Spring application. If you are not familiar with Java configuration then please check Spring Documentation to learn more about it. 

3. JDBC Driver File in Tomcat Lib 

Now the final step is to make sure tomcat lib has a JDBC driver jar file. I usually put the JAR file inside the lib directory of tomcat but you can put it anywhere it makes sense and modifies the tomcat classpath to include driver JAR into the classpath. 


Now the rest of the code that uses this data source should remain the same. You can get the Spring DAO source from the previous article How to setup the Database Connection pool in the Spring framework.

That's all about how to set up the JNDI Database connection pool in Tomcat. You can follow these steps to set up a  DB Connection pool for your application. Remember, you should always use a DB connection pool whenever you connect to the database. This is a common best practice and it will significantly improve the performance of your Java web application.  

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