支付宝的接口调用很不方便，刚做好一个封装，实现了虚拟交易和实物交易。
解决方案中有三个项目以及NDoc生成的文档，简单的序列图：CommonAliPay，封装的支付宝接口。
 TestAli,asp.net的测试项目
TestCommonAliPay，Nunit的测试项目。
调用方法：
1、引入CommonAliPay.dll
2、实现支付宝服务接口的方法调用方式：
 AliPay ap = new AliPay();
        string key = "";//填写自己的key
        string partner = "";//填写自己的Partner
        StandardGoods bp = new StandardGoods("trade_create_by_buyer", partner, key, "MD5", "卡2", Guid.NewGuid().ToString(), 2.551m, 1, "hao_ding2000@yahoo.com.cn", "hao_ding2000@yahoo.com.cn"
            , "EMS", 25.00m, "BUYER_PAY","1");
           bp.Notify_Url = "http://203.86.79.185/ali/notify.aspx";
        ap.CreateStandardTrade("https://www.alipay.com/cooperate/gateway.do", bp, this);上面是通用的调用方式。
下面是只支持虚拟货物的方式：
 string key = "";//填写自己的key
        string partner = "";//填写自己的Partner
        AliPay ap = new AliPay();
        DigitalGoods bp = new DigitalGoods("create_digital_goods_trade_p", partner, key, "MD5", "卡2", Guid.NewGuid().ToString(), 2.551m, 1, "hao_ding2000@yahoo.com.cn", "hao_ding2000@yahoo.com.cn");
        bp.Notify_Url = "http://203.86.79.185/ali/notify.aspx";
        ap.CreateDigitalTrade("https://www.alipay.com/cooperate/gateway.do", bp, this);3、实现支付宝通知接口方法的调用（支持虚拟和实物）：
protected void Page_Load(object sender, EventArgs e)
    {
      
        string key = "";//填写自己的key
        string partner = "";//填写自己的Partner
         AliPay ap = new AliPay();
         string notifyid = Request.Form["notify_id"];
         Verify v = new Verify("notify_verify", partner, notifyid);
        ap.WaitSellerSendGoods+=new AliPay.ProcessNotifyEventHandler(ap_WaitSellerSendGoods);
        ap.WaitBuyerPay += new AliPay.ProcessNotifyEventHandler(ap_WaitBuyerPay);
        ap.ProcessNotify(this, "https://www.alipay.com/cooperate/gateway.do",key,v, "utf-8");
    }

    void ap_WaitBuyerPay(object sender, NotifyEventArgs e)
    {
        // //加入自己的处理逻辑
        Log4net.log.Error("wait buyer pay fire");
    }

  
    private void ap_WaitSellerSendGoods(object sender, NotifyEventArgs e)
    {
        //加入自己的处理逻辑
        Log4net.log.Error("WaitSellerSendGoods fire");
    }支付宝的交易状态都被定义成了类似名称的事件。
部分源代码解析：
1、解析Forms集合到NotifyEventArgs类，因为后面此类的数据要用来做MD5Sign，所以所有值类型，不能存在初始值，如：int的0等。因此用Nullable范型。
   private NotifyEventArgs ParseNotify(NameValueCollection nv, object obj)
        {
            PropertyInfo[] propertyInfos = obj.GetType().GetProperties(BindingFlags.Public | BindingFlags.Instance);

            foreach (PropertyInfo pi in propertyInfos)
            {
                string v = nv.Get(pi.Name.ToLower());
                if (v != null)
                {
                    if (pi.PropertyType == typeof(string))
                    {

                        pi.SetValue(obj, v, null);

                    }
                    else if (pi.PropertyType == typeof(int?))
                    {
                        pi.SetValue(obj, int.Parse(v), null);
                    }
                    else if (pi.PropertyType == typeof(decimal?))
                    {

                        pi.SetValue(obj, decimal.Parse(v), null);
                    }
                    else if (pi.PropertyType == typeof(DateTime?))
                    {

                        pi.SetValue(obj, DateTime.Parse(v), null);
                    }
                    else if (pi.PropertyType == typeof(bool))
                    {

                        pi.SetValue(obj, bool.Parse(v), null);
                    }
                    else
                    {
                        //转型失败会抛出异常
                        pi.SetValue(obj, v, null);
                    }
                }

            }
            return (NotifyEventArgs)obj;

        }
2、从类型中获取排序后的参数
 /**//// <summary>
        /// 获取排序后的参数
        /// </summary>
        /// <param name="obj"></param>
        /// <returns></returns>
        private SortedList<string,string> GetParam(object obj)
        {
           
            PropertyInfo[] propertyInfos = obj.GetType().GetProperties(BindingFlags.Public|BindingFlags.Instance);         
            SortedList<string, string> sortedList = new SortedList<string, string>(StringComparer.CurrentCultureIgnoreCase);
            foreach (PropertyInfo pi in propertyInfos)
            {

                if (pi.GetValue(obj, null) != null)
                {
                    if (pi.Name == "Sign" || pi.Name == "Sign_Type")
                    {
                        continue;
                    }
                    sortedList.Add(pi.Name.ToLower(), pi.GetValue(obj, null).ToString());
                 
                }
            }
            return sortedList;
                   
        }3、从SortedList中产生参数
 private string GetUrlParam(SortedList<string, string> sortedList,bool isEncode)
        {
            StringBuilder param = new StringBuilder();
            StringBuilder encodeParam = new StringBuilder();
            if (isEncode == false)
            {

                foreach (KeyValuePair<string, string> kvp in sortedList)
                {
                    string t = string.Format("{0}={1}", kvp.Key, kvp.Value);
                    param.Append(t + "&");
                }
                return param.ToString().TrimEnd('&');
            }
            else
            {
                foreach (KeyValuePair<string, string> kvp in sortedList)
                {
                     string et = string.Format("{0}={1}", HttpUtility.UrlEncode(kvp.Key), HttpUtility.UrlEncode(kvp.Value));
                     encodeParam.Append(et + "&");
                }
                return encodeParam.ToString().TrimEnd('&');
            }
 
        }
下载地址：http://www.cnblogs.com/Files/bluewater/CommonAliPay.rar