session[“username”]=null;//Session.Remove(“username”);的结果是session[“username”]=null了
session[“username”]=””;
session.clear();//表示将会话中所有的session的键值都清空，但是session还是依然存在，同等于Session.RemoveAll()
session.abandon();
//---------------------------------自己写的小栗子----------------------------------------------------------------------------------
Session["username"] = "xxj";
Response.Write("username:"+Session["username"]);
//Session.Remove("username");//值为NULL
//Session.Abandon();//值不为NULL,为xxj
Session.Clear();//Session.Clear只是清除Session中的所有数据并不会中止该Session,值为NULL
//Response.Write("移除后的username:" + Session["username"]);
if (Session["username"] == null)
{
Response.Write("session["username"]真的为NULL了");
}
else
{
Response.Write("session["username"]不为NULL,session["username"]的值为" + Session["username"]);
}
参考：http://www.cnblogs.com/shuang121/archive/2011/03/02/1968768.html