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

修改為

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;  
}