HttpServlet Class:

- HttpServlet class extends the GenericServlet class and implements Serializable interface.
- It provides http specific methods such as doGet(), doPost() etc which handle GET request and POST request respectively.

Program to Calculate SI using HttpServlet and JSP

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/SIServlet")
public class HtServlet extends HttpServlet{

	private static final long serialVersionUID = 1L;
	
	public SIServlet() {
		super();
	}
	
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		request.getRequestDispatcher("siform.jsp").forward(request, response);
	}
	
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException,IOException {
		
		Integer p = Integer.parseInt(request.getParameter("principal"));
		Integer t = Integer.parseInt(request.getParameter("time"));
		Integer r = Integer.parseInt(request.getParameter("rate"));
		
		float si = p*t*r/100;
		
		request.setAttribute("answer", si);
		
		request.getRequestDispatcher("result.jsp").forward(request, response);
	}

}