// 设置验证规则 验证email
$rules['Email'] = 'trim|required|valid_email';
$this->validation->set_rules($rules);
// 验证密码是否正确
if ($this->validation->run() === TRUE)
{
$rules['Passwd'] = 'required|md5|callback__login_check';
$this->validation->set_rules($rules);
}