@WebServlet(name = "SignInServlet", urlPatterns = {"/SignInServlet"})
public class SignInServlet extends HttpServlet
{
    public void doGet(HttpServletRequest req, HttpServletResponse resp)
        throws ServletException, IOException
{
    String login = req.getParameter("login");
    String password = req.getParameter("password");
    String role;

    resp.setContentType("text/html;charset=utf-8");
    PrintWriter pw = resp.getWriter();

    Connection conn = null;

    String url = "jdbc:postgresql://127.0.0.1:5432/crm";
    String name = "vladimir";
    String pass = "1234";
    try
    {
        Class.forName("org.postgresql.Driver");
        conn = DriverManager.getConnection(url, name, pass);
        Statement statement = null;
        statement = conn.createStatement();
        JOptionPane.showMessageDialog(null,conn.toString());
        ResultSet result1 = statement.executeQuery("SELECT * FROM users");
        while (result1.next())
        {
            if((password.equals(result1.getString("password"))) &&
                    (login.equals(result1.getString("login"))))
            {
                role = result1.getString("userrole");
                getServletContext().
                        getRequestDispatcher("/signiinsucces.jsp").
                        forward(req, resp);
            }
            /*else if((!password.equals(result1.getString("password"))) &&
                    (!login.equals(result1.getString("login"))))
            {
                getServletContext().
                        getRequestDispatcher("/signiinfail.jsp").
                        forward(req, resp);
            }*/
        }
    }
    catch (Exception ex)
    {
        ex.printStackTrace();
        getServletContext().
                getRequestDispatcher("/error.jsp").
                forward(req, resp);
    }
    finally
    {
        if (conn != null)
        {
            try
            {
                conn.close();
            }
            catch (SQLException ex)
            {
                getServletContext().
                        getRequestDispatcher("/error.jsp").
                        forward(req, resp);
            }
        }
    }
}
}