C# session操作

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;
            }

        }
 

           
      
    }
}