JNDI Lookup in Servlet - Design Question

Question

I will appreciate if someone answers/clarifies my following questions.
I am using Tomcat Connection pooling.
1. If I understand correctly- with Connection Pooling - Server will take
care of opening the connections with DB
So if the Max users allowed is 10, it means that at any given time 10
Concurrent users will be allowed access to DB.
2.. Where do I place the code for doing the context lookup?
I have many servlets called by JSP pages and these servlets will be
accessing Database.
(a) Shall I place the context lookup code in each of the servlets Init
Method, but by doing so I am writing the same code again and
again.
If I understand correctly the Context lookup code is following 3 lines
or Can I squeeze more code in Init()
Context i = new InitialContext();
Context e = (Context) i.lookup("java:comp/env");
DataSource d = (DataSource) e.lookup("jdbc/mytestdb");
Again if I have 30 Servlets, is this still a good idea?
(b) If there is an alternative to 2 (a), like having another class or
something, please elaborate on that and which part of code should
be in this alternative.
My application will be using JSP pages to call servlets that access Database to update or display results.
Thank you very much.

Answer 1

Thanks for reply.
Yes, I have read that putting connection code in init of servlet is not good. Hence
I have now a DbHelper Class that takes care of opening and returning a Connection when called.
Servlets call this DbHelper class to get connection.
Is the following a good idea?
DbHelper.java
import javax.naming.*;
import javax.sql.*;
import java.sql.*;
public class DbHelper {
     //private final static String DATASOURCENAME  = "java:comp/env/jdbc/schooljsp";
     public static Connection getConnection(String jndiName){
          System.out.println(jndiName);
          try {     
         Context ctx = new InitialContext();
          DataSource datasource = (DataSource)ctx.lookup(jndiName);
          Connection con = null;
               if (datasource != null) {
                  con = datasource.getConnection();
               return con;
     }  catch (NamingException ex){
            throw new RuntimeException("Init: Cannot get connection" + ex);
       }  catch ( SQLException e){
           throw new RuntimeException("Cannot get Connections from Datasource");
}And MY Servlet code
public class AuthServlet1 extends HttpServlet {
     private final static String DATASOURCENAME  = "java:comp/env/jdbc/schooljsp";
     public void doGet(HttpServletRequest req, HttpServletResponse res)
          throws ServletException, IOException {
          res.setContentType("text/html");
          PrintWriter out = res.getWriter();
      try {
          Connection conn = DbHelper.getConnection(DATASOURCENAME);
          Statement stmt = conn.createStatement();
          ResultSet rs = stmt.executeQuery("select * from SIGNUP");
           out.println("SIGNUP<br>");
          while (rs.next()) {
               out.print(rs.getString(1));
               out.print(" ");
               out.print(rs.getInt(2));
               out.println("<br>");
          rs.close();
          stmt.close();
        }catch (Exception e) { System.out.println("Error e : " + e); }
}Or I can make it more robust and better?
Thanks a lot.