list+=request.getParameter("id")+",";到底有什么作用呀,不太能看懂这句代码
举个栗子:
String list = "hello";
list += request.getParameter("id") + ",";
等价于
list = list + request.getParameter("id") + ",";
如果获取到的id参数为 5,那么最终list的值为
list = "hello5";
每次浏览把当前浏览的商品编号加到list中去 也就是cookie