LoginServlet.java

package ris_i_bd;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LoginServlet extends HttpServlet {
@Override
    protected void doPost(HttpServletRequest req,
                          HttpServletResponse resp) throws ServletException, IOException {

        if ("logout".equals(req.getParameter("act"))) {
            req.getSession().removeAttribute("user");
        } else {
            String email = req.getParameter("email");
            String pass = req.getParameter("pass");
            Connection con = DataBase.getConnection();
            String sql = "select * from users1 where email = ? and pass = ?";
            try (PreparedStatement st = con.prepareStatement(sql)) {
                st.setString(1, email);
                st.setString(2, pass);
                try (ResultSet rs = st.executeQuery()) {
                    if (rs.next()) {
                        final User user = new User(email, pass);
                        req.getSession().setAttribute("user", user);
                    } else {
                        req.setAttribute("login_failed", true);
                    }
                }
            } catch (SQLException ex) {
                throw new RuntimeException(ex);
            }
        }
        req.getRequestDispatcher("/index.jsp").forward(req, resp);

    }
}