Erro no Servelt/DAO

public void open()
{
 try{
    Class.forName("com.mysql.jdbc.Driver");
    Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/exemplodao","root","cyro");     
        
 
 }catch(Exception e)
 {

 }

}
public void close(){
    //e a morte , não é minha culpa 
    try{
        con.close();
    }catch(Exception e) {
    }
}

public class ClienteDao extends Dao1

{

PreparedStatement stmt;

public void inserirDados(String nome,String email)
{
    try{
        stmt=con.prepareStatement("insert into tb_cliente(nome,email) values(?,?)");
        stmt.setString(1,nome);
        stmt.setString(2,email);
        stmt.execute();
        stmt.close();
                   
    }catch (Exception e)
    {
                
    }
}

protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
    response.setContentType("text/html;charset=UTF-8");
    PrintWriter out = response.getWriter();
   
    try{
    // Exception e= new Exception();   
    String nome=request.getParameter("nome");
    String email=request.getParameter("email");
    Cliente cli=new Cliente();
    cli.setNome(nome);
    cli.setEmail(email);
    ClienteDao x= new ClienteDao();
    x.open();
    x.inserirDados(cli.getNome(),cli.getEmail());
   // out.print(e.getMessage());
    out.print("Dados Gravados");     
    
    
    out.close();
}catch(Exception e){
    out.print(e.getMessage());
     }
}

// <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
/** Handles the HTTP <code>GET</code> method.
 * @param request servlet request
 * @param response servlet response
 */
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
    processRequest(request, response);
}

/** Handles the HTTP <code>POST</code> method.
 * @param request servlet request
 * @param response servlet response
 */
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
    processRequest(request, response);
}

/** Returns a short description of the servlet.
 */
public String getServletInfo() {
    return "Short description";
}
// </editor-fold>