#5_HTTPServletRequest_and_Response

--> public void doGet(HttpServletRequest req , HttpServletResponse res) throws IOException, ServletException 
	{
		int i = Integer.parseInt(req.getParameter("num1"));
		int j = Integer.parseInt(req.getParameter("num2"));
		
		int k = i + j;
		
		// Session Management --> concept used to print the added value in this case. Data is shared from one Servlet to another
		
		req.setAttribute("k", k);
		
		PrintWriter out = res.getWriter();
		out.println("Result is: " +k); 
		
		// To call servlet we have two methods:
		// 1. Request Dispatcher (Req Dis)
		// 2. Redirect (Redirect)
		
		RequestDispatcher rd = req.getRequestDispatcher("sq");
		rd.forward(req, res);	
	}
	
=================================================== Theoretical ===============================================

--> Request Disaptcher (Rd) --> Rd is used to connect two Servlet Ex: When from client side a request is made then if we have two servlets, one is website and other is 
                                                                          payment gateway then this Rd is used.
									  
					--> But when we want to redirect to payment gateway then Sendredirect() method is used. In this the page will say you are being 
					     redirected.
					--> In redirect two different request object is used.
					
==================================== URL Rewriting ==============================================================================

package com.servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class AddServlet extends HttpServlet 
{

	public void doGet(HttpServletRequest req , HttpServletResponse res) throws IOException, ServletException 
	{
		int i = Integer.parseInt(req.getParameter("num1"));
		int j = Integer.parseInt(req.getParameter("num2"));
		
		int k = i + j;
		
		// Session Management --> concept used to print the added value in this case. Data is shared from one Servlet to another
		
		res.sendRedirect("sq?k="+k);// Hey client just go to square servlet 
									// --> Here we used 3. URL Rewriting. --> Another way: 1.Cookies
		                            //		                                               2.Session Management
		
		
		
		
		
		
		
		
																									//		             --> Session Management