JNDI datasource configuration using tomcat in java

server.xml

 Context configuration

...............
 <context>

<Resource name="jdbc/myoracle" auth="Container"
              type="javax.sql.DataSource" driverClassName="oracle.jdbc.OracleDriver"
              url="jdbc:oracle:thin:@127.0.0.1:1521:mysid"
              username="scott" password="tiger" maxActive="20" maxIdle="10"
              maxWait="-1"/>

  </context>

 web.xml configuration

 <web-app xmlns="http://java.sun.com/xml/ns/j2ee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
    version="2.4">
  <description>OracleTest App</description>
 <resource-ref>
 <description>Oracle Datasource example</description>
 <res-ref-name>jdbc/myoracle</res-ref-name>
 <res-type>javax.sql.DataSource</res-type>
 <res-auth>Container</res-auth>
</resource-ref>
</web-app>

.

Code example

Context initContext = new InitialContext();
Context envContext  = (Context)initContext.lookup("java:/comp/env");
DataSource ds = (DataSource)envContext.lookup("jdbc/myoracle");
Connection conn = ds.getConnection();
//etc.