C# 类库如何引用session

C# 类库怎么引用session
如题！在.net C#类库中需要用到session值，请问怎么实现？最好有实例~~多谢!

[解决办法]
System.Web.UI.Page page = HttpContext.Current.Handler as System.Web.UI.Page;
object xx= page.Session["xxx"];
[解决办法]
添加System.Web引用,然后导入以下两个命名空间
using System.Web;
using System.Web.Security;

然后取值：
object o = HttpContext.Current.Session["***"];