How to Use JNDI in websphere (get connect string database websphere)

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.servlet.Servlet;
import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.sql.DataSource;

/**
 * @version  1.0
 * @author
 */
public class JuliDataServlet extends HttpServlet implements Servlet 
{

 public void doGet(HttpServletRequest req, HttpServletResponse resp)
  throws ServletException, IOException 
 {
  doPost( req,  resp);
 }
 public void doPost(HttpServletRequest req, HttpServletResponse resp)
  throws ServletException, IOException 
 {
  Connection conn=null;
  PrintWriter out=resp.getWriter();
  try{
   //JNDI
   Context aContext = new InitialContext();
   DataSource aDataSource = (DataSource)aContext.lookup("java:comp/env/ExtDS");
   conn = aDataSource.getConnection();
   //JNDI end

   //raw JDBC for the same SAMPLEsample DB2 database 
   //Class.forName("COM.ibm.db2.jdbc.app.DB2Driver"); //need db2java.zip in the path 
   //conn = DriverManager.getConnection("jdbc:db2:sample"); //DB2
   //raw JDBC end

   String firstname="";
   String sql = "select firstnme, lastname from employee";
   Statement stm = conn.createStatement();
   ResultSet rst = stm.executeQuery(sql);
   for (int i=0; (i<10 && rst.next()); i++)  //only print 10 names
   {
    firstname =  rst.getString("firstnme");
    out.println("Hello "+ firstname+"," );
   }
   if(conn != null)
   {
    conn.close();
    System.out.println("Successfully closed");  
   }
  }
  catch (Exception e)
  {
   System.out.println(e);
  }
 
 }
}

==============================

ExtDS : Alias JNDI in websphere

=================================

Config file : ibm-web-bnd.html

<?xml version="1.0" encoding="UTF-8"?>
<web-bnd 
    xmlns="http://websphere.ibm.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://websphere.ibm.com/xml/ns/javaee 

http://websphere.ibm.com/xml/ns/javaee/ibm-web-bnd_1_0.xsd"
    version="1.0">

   <resource-ref>
  <res-ref-name>ExtDS</res-ref-name>
  <jndi-name>ExtDS</jndi-name>
</resource-ref>
</web-bnd>

==================================

Config file : web.xml

<resource-ref>
    <description>
    Datasource connection to db</description>
    <res-ref-name>ExtDS</res-ref-name>
    <res-type>javax.sql.DataSource</res-type>
    <res-auth>Container</res-auth>
  </resource-ref>