2种方法:    1.  将JS的值存放 <inpu type='hidden' ...> 隐藏域中,然后在JSP中捕获.
    2.  在JS端组合 URL ,比如         <script>
            var i = 100;
            var url = 'server.jsp?i=' + i;            document.location.href= url; 
         </script>        对应的JSP 程序
        
        <%
              int client_i = Integer.parseInt(request.getParameter("i"));
              int server_i = client_i;
   
         %>