ajax跨域session失效,request跨域获取session失效

如下代码，传到另外一个域名就获取不到session了

(localhost:12402/Home/Index)

Session["MemberUser"]=123456;

string url = "api/Home/GetTop8FileDown";

string result = CrossJs.DoGet(ApiUrl + url );

public static string DoGet(string url)

{

CookieContainer cookieContainer = new CookieContainer();

string serviceAddress = url;

HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(serviceAddress);

request.Method = "GET";

request.ContentType = "application/json";

HttpWebResponse response =(HttpWebResponse)request.GetResponse();

using (StreamReader dataStream = new StreamReader(response.GetResponseStream()))

{

var result = dataStream.ReadToEnd();

return result;

}

}

(localhost:2412/Home/Index)

public string GetTop8FileDown()

{

int MemberId = Convert.ToInt32(HttpContext.Current.Session["MemberUser"]);

var member = (from a in db.ec_Member where a.MemberID == MemberId select a).FirstOrDefault();

}

一直获取不到这一个HttpContext.Current.Session["MemberUser"] 。