基于COOKIE技术实现的购物车类

using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Web;
using System.Collections.Specialized;

namespace EWSLSite.Bll
...{
    /**//// <summary>
    /// 购物车
    /// </summary>
    public  class EWSLShop_ShopCart
    ...{
        /**//// <summary>
        /// 放进购物车
        /// </summary>
        /// <param name="ID">产品编号</param>
        public void Add(string ID)
        ...{
            //读区购物车COOKIE信息
            NameValueCollection nv = GetCart();
            if (string.IsNullOrEmpty(nv[ID]))
            ...{
                //不存在，添加
                nv.Add(ID, "1");
            }
            else
            ...{
                //存在，数量加一
                int n = int.Parse(nv[ID]);
                n++;
                nv.Set(ID, n.ToString());
            }
            Save(nv);
        }
        /**//// <summary>
        /// 从购物车中去除商品
        /// </summary>
        /// <param name="ID"></param>
        public void Del(string ID)
        ...{
            NameValueCollection nv = GetCart();
            nv.Remove(ID);
            Save(nv);
        }
        /**//// <summary>
        /// 清空购物车
        /// </summary>
        public void Clear()
        ...{
            HttpContext.Current.Response.Cookies["CartList"].Value = "";
        }
        /**//// <summary>
        /// 获取购物车中的商品总数
        /// </summary>
        /// <returns></returns>
        public int GetNum()
        ...{
            int n = 0;
            n = GetCart().Keys.Count;
            return n;
        }
        /**//// <summary>
        /// 更改订购数量
        /// </summary>
        public void SetNum(string ID, int Num)
        ...{
            NameValueCollection nv = GetCart();
            if (string.IsNullOrEmpty(nv[ID]))
            ...{
                nv.Add(ID, Num.ToString());
            }
            else
            ...{
                nv.Set(ID, Num.ToString());
            }

            Save(nv);
        }
        /**//// <summary>
        /// 获取定单列表
        /// </summary>
        /// <returns></returns>
        public DataTable GetList()
        ...{
            NameValueCollection nv = GetCart();
            string IDs = "";
            for (int i = 0; i < nv.Count; i++)
            ...{
                if (IDs.Length > 0)
                ...{
                    IDs += "," + nv.GetKey(i);
                }
                else
                ...{
                    IDs += nv.GetKey(i);
                }
            }
            EWSLShop_Product handle = new EWSLShop_Product();
            DataTable dt = handle.GetProInfo(IDs);
            dt.Columns.Add("Num", typeof(int));  //数量
            dt.Columns.Add("Sum", typeof(string));  //小计金额
            dt.Columns.Add("ID", typeof(int));  //排序
            dt.Columns.Add("price", typeof(string));
            for (int i = 0; i < dt.Rows.Count; i++)
            ...{
                string PID = dt.Rows[i]["PID"].ToString();
                if (string.IsNullOrEmpty(nv[PID]))  //获取产品的数量
                ...{
                    dt.Rows[i]["Num"] = 1;
                }
                else
                ...{
                    dt.Rows[i]["Num"] = nv[PID];
                }
                dt.Rows[i]["ID"] = GetNvIndex(nv, PID);

                decimal sum = Convert.ToDecimal(dt.Rows[i]["price"]) * Convert.ToInt32(dt.Rows[i]["Num"]);
                dt.Rows[i]["Sum"] = sum.ToString("c");
            }
            dt.DefaultView.Sort = "ID";
            return dt;
        }
        /**//// <summary>
        /// 从COOKIE读取购物车信息
        /// </summary>
        /// <returns></returns>
        private NameValueCollection GetCart()
        ...{
            NameValueCollection nv = new NameValueCollection();  //商品 ID、购买数量
            if (HttpContext.Current.Request.Cookies["CartList"] != null)
            ...{
                nv = HttpContext.Current.Request.Cookies["CartList"].Values;
            }
            return nv;
        }
        private int GetNvIndex(NameValueCollection nv, string Key)
        ...{
            for (int i = 0; i < nv.Keys.Count; i++)
            ...{
                if (nv.GetKey(i) == Key)
                ...{
                    return i;
                }
            }
            return -1;   //没有找到
        }
        /**//// <summary>
        /// 将信息写入COOKIE
        /// </summary>
        /// <param name="nv"></param>
        private void Save(NameValueCollection nv)
        ...{
            HttpCookie cookie = new HttpCookie("CartList");
            cookie.Expires = DateTime.Now.AddDays(31);
            /**////将信息写到添加COOKIE中
            foreach (string key in nv.AllKeys)
            ...{
                cookie[key] = nv[key];
            }
            HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.GetEncoding("gb2312");
            HttpContext.Current.Response.Cookies.Set(cookie);
        }
    }
}