This blog is written with the aim to show JNDI DataSource configuration for a web container like tomcat.
JNDI stands for Java Naming and Directory Interface, a directory service provided for java-based client applications to search and look up objects with names.
DataSource is a name to the connection setup to a database on a server.
In this blog, we are going to setup JNDI DataSource for MySQL database.

Create a Sample Database

I have created following database and table inside.

create database usersdb;

use usersdb;

CREATE TABLE `users` (
  `user_id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(45) NOT NULL,
  `password` varchar(45) NOT NULL,
  `email` varchar(45) NOT NULL,
  PRIMARY KEY (`user_id`)
);

Configure Tomcat context

Add the Resource in Context.xml in $CATALINA_BASE/conf/context.xml

<Resource
    name="jdbc/UsersDB"
    auth="Container"
    type="javax.sql.DataSource"
    maxActive="100"
    maxIdle="30"
    maxWait="10000"
    driverClassName="com.mysql.jdbc.Driver"
    url="jdbc:mysql://localhost:3306/usersdb"
    username="root"
    password=""
    />

Configure web.xml

Add the following resource-ref in your project's web.xml

<resource-ref>
    <description>DB Connection</description>
    <res-ref-name>jdbc/UsersDB</res-ref-name>
    <res-type>javax.sql.DataSource</res-type>
    <res-auth>Container</res-auth>
</resource-ref>

Now the JNDI DataSource configured for your application. You can have the DataSource as following -

InitialContext context = new InitialContext();
Context envContext = (Context) context.lookup("java:comp/env");
DataSource dataSource = (DataSource) envContext.lookup("jdbc/UsersDB");

Thanks.