Passando valores para o servlet

package Servlet;
import java.io.IOException;

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

import br.com.SuperLivros.VO.*;
import br.com.SuperLivros.DAO.*;

import java.sql.SQLException;
import java.util.*;
/**
 * @author rafa
 *
 * To change the template for this generated type comment go to
 * Window>Preferences>Java>Code Generation>Code and Comments
 */
public class AdcionarAoCarrinhoServlet extends HttpServlet {

	private int Codigo;
	
	protected void doPost(HttpServletRequest request,HttpServletResponse response)
		throws ServletException, IOException {
			
			Codigo = Integer.parseInt(request.getParameter("Codigo"));
		
		SuperLivros su = new SuperLivros();
		SuperLivros su2 = new SuperLivros();
		LivroDAO li = new LivroDAO();
		Vector lista = new Vector();
		
		
		su.setId_livro(Codigo);
		try {
			su2 = li.BuscaLivro(su);
		} catch (SQLException e) {
			System.out.println("Adicionar no carrionho: "+ e);
			e.printStackTrace();
		} catch (ClassNotFoundException e) {
			System.out.println("Adicionar no carrionho: "+ e);
			e.printStackTrace();
		}
		lista.add(su2);
		
		HttpSession session = request.getSession();
		session.setAttribute("carrinho",lista);
		
		response.sendRedirect("../visualisaCarrinho.jsp");
	}
}