$smarty->display('goods.dwt',      $cache_id);

修改为

switch ($goods['cat_id'])){
case 1:
  $smarty->display('goods.dwt',      $cache_id);
  break; 
case 2:
  $smarty->display('goods1.dwt',      $cache_id);
  break; 
case 3:
  $smarty->display('goods2.dwt',      $cache_id);
  break; 
case 4:
  $smarty->display('goods3.dwt',      $cache_id);
  break; 
}