Connection to Database Using JNDI

A Java application can connect to a database through JNDI by defining a container-managed data source in the web application configuration and looking it up from a Java class.

Create the Environment

Create the Database User

Create a database and user with the following values used in the source example:

Configure context.xml

Add the JNDI data-source resource to the application context.xml file:

<Context antiJARLocking="true" path="/JNDI">
    <Resource name="jdbc/jelasticDb"
              auth="Container"
              type="javax.sql.DataSource"
              maxActive="100"
              maxIdle="30"
              maxWait="10000"
              username="jelastic"
              password="jelastic"
              driverClassName="com.mysql.jdbc.Driver"
              url="jdbc:mysql://mysql-jndi-example.{hoster_domain}/jelasticDb"/>
</Context>

Configure web.xml

Declare the JNDI resource reference in the application web.xml file:

<resource-ref>
    <description>MySQL Datasource example</description>
    <res-ref-name>jdbc/jelasticDb</res-ref-name>
    <res-type>javax.sql.DataSource</res-type>
    <res-auth>Container</res-auth>
</resource-ref>

Create the Java Connection Class

Create a Java class that retrieves the data source from the application-server naming context and returns database connections:

public class MyConnection {
    private DataSource dataSource;

    public MyConnection() {
        try {
            InitialContext context = new InitialContext();
            dataSource = (DataSource) context.lookup(
                "java:comp/env/jdbc/jelasticDb"
            );
        } catch (NamingException ex) {
            Logger.getLogger(
                MyConnection.class.getName()
            ).log(Level.SEVERE, null, ex);
        }
    }

    public Connection getConnection() {
        Connection conn = null;

        try {
            conn = dataSource.getConnection();
        } catch (SQLException ex) {
            Logger.getLogger(
                MyConnection.class.getName()
            ).log(Level.SEVERE, null, ex);
        }

        return conn;
    }
}

The lookup path used by the class is:

java:comp/env/jdbc/jelasticDb

Expected Result

The Java application obtains a container-managed DataSource through JNDI and uses it to create database connections to the configured MySQL database.

Important Notes

• Create the database node before configuring the web application.
• Replace {hoster_domain} with the domain used by the hosting provider.
• Keep the JNDI resource name consistent across all configuration files and Java code.
• Ensure that the MySQL JDBC driver is available to the application server.
• Replace the example username and password with secure credentials.
• Review application-server and application logs when the JNDI lookup fails.

Common Issues and Solutions