code: public static void removeActionForm(ActionMapping mapping, HttpServletRequest request) {
  		if (mapping.getAttribute() != null) {
  			if ("request".equals(mapping.getScope()))
  				request.removeAttribute(mapping.getAttribute());
  			else {
  				HttpSession session = request.getSession();
  				session.removeAttribute(mapping.getAttribute());
  				request.removeAttribute(mapping.getAttribute());
  			}
  		}
  	}
docs: 删除保存在attribute中的ActionForm实例
  
  @param mapping
  @param request