Session creation Using servlet

Using Java Servlet session variable is a mechanism to store user’s data in server. And sessions will last till we are on the site, it will be destroyed when the user quit the site.
One main example of session usage is login information. When a user login to a site with his user name and password, sessions will be created for that user in server. By using these session variables servers  programs identify each user

Now let's consider about how to write data in to session and read data from the session:

package servlets.first;



import java.io.IOException;

import java.io.PrintWriter;



import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpSession;



/**

 * Servlet implementation class SessionTest

 */

@WebServlet(description = "Write data to session and read data from session as well", urlPatterns = { "/SessionTest" })

public class SessionTest extends HttpServlet {

    private static final long serialVersionUID = 1L;



    /**

     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)

     */

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        response.setContentType("text/html");

        String uname=request.getParameter("uname");       

        PrintWriter out=response.getWriter();

       

        HttpSession session =request.getSession();// Creation of session object 

        session.setAttribute("Sname",uname);

        out.println("Username From session:"+ (String)session.getAttribute("Sname"));//Read session data

        out.println("Username:"+uname);

       

               

    }

}

Now let run the servlet through this url

http://localhost:8080/servletandjsp/SessionTest?uname=sudeep


the the out put will be looks like this:

Username From session:sudeep Username:sudeep