this.action = request.getParameter("action");
中的action在哪里设置它为add,show等属性?
link: '<%=path%>/servlet/CartServlet?id='+id+'&num='+num+'&action=add'
servlet/CartServlet?action=show
servlet/CartServlet?action=remove&id=<%=item.getId()%>
跳转Servlet时设置