//servlet设置session值
ShoppingCart sc=(ShoppingCart)session.getAttribute("cart");
if(sc==null){
sc=new ShoppingCart();
session.setAttribute("cart",sc);
}
//客户端取得session值
ShoppingCart sc=(ShoppingCart)session.getAttribute("cart");
//Servlet中设置属性值
request.setAttribute("items",aL);
//客户端读取Attribute 值
List aL=(List)request.getAttribute("items");
//客户端传字符串参数
<a href='?oper=buy&id="+item.getId()+"'>"+item.getName()+"</a>
//servlet提取request参数
String oper=request.getParameter("oper");
String _id=request.getParameter("id");