code: @RequestMapping(method = RequestMethod.POST, params = "action=chooseSkin")
      public ModelAndView chooseSkin(HttpServletRequest request, @RequestParam String skinName)
              throws IOException {
  
          this.stylesheetUserPreferencesService.setStylesheetParameter(
                  request, PreferencesScope.THEME, "skin", skinName);
  
          return new ModelAndView("jsonView", Collections.emptyMap());
      }
docs: Update the user's preferred skin.
  
  @param request HTTP Request
  @param skinName name of the Skin
  @throws IOException
  @throws PortalException