using System;using System.Collections.Generic;using System.Text;using System.Web;using System.Web.SessionState;namespace OAFrameWork{  public class CSession  {      public static object Get(string Key)    {      return HttpContext.Current.Session[Key];    }  public static string GetString(string Key)    {      object obj = HttpContext.Current.Session[Key];      if (obj == null) return "";      else return obj.ToString();    }    public static object Get(string Key,object DefaultValue)    {      if (HttpContext.Current.Session[Key] == null)        return DefaultValue;      else        return HttpContext.Current.Session[Key];    }    public static object Get(string Key, object DefaultValue,Boolean CanAdd)    {      if (HttpContext.Current.Session[Key] == null)      {        if(CanAdd==true)          HttpContext.Current.Session.Add(Key, DefaultValue);        return DefaultValue;      }      else        return HttpContext.Current.Session[Key];    }    public static Boolean Set(string Key,object Value)    {      try      {        if (Value == null && HttpContext.Current.Session[Key] != null)        {          HttpContext.Current.Session.Remove(Key);        }        else if (HttpContext.Current.Session[Key] == null)          {            HttpContext.Current.Session.Add(Key, Value);          }          else          {            HttpContext.Current.Session[Key] = Value;          }        return true;      }      catch (Exception ex)      {        CMsgBox.Show(ex.Message);         return false;      }    }             }}

Session.Abandon();//清除全部Session//清除某個SessionSession["UserName"] = null;Session.Remove("UserName");