ASP.NET Request.Cookies.Get（「Cookie」）返回Null

這個問題似乎已被問了很多次，但我找不到幫助我的答案。ASP.NET Request.Cookies.Get（「Cookie」）返回Null

我有一個母版頁文件的代碼隱藏代碼，當下拉控件更改時，它會設置一個cookie。如果我註釋掉重定向行，我可以看到cookie已正確設置，因爲創建新的cookie併成功輸出其值會顯示已更改下拉菜單的新值。

但是，如果我允許重定向發生，page_load中的代碼將報告cookie集爲空。任何幫助是極大的讚賞！

protected void ThemeSelection_SelectedIndexChanged(object sender, EventArgs e) 
{ 

    HttpCookie themeCookie = new HttpCookie("PreferredTheme"); 
    themeCookie.Expires = DateTime.Now.AddMonths(3); 
    themeCookie.Value = ThemeSelection.SelectedValue; 

    Request.Cookies.Add(themeCookie); 

    HttpCookie cookieCheck = Request.Cookies.Get("PreferredTheme"); 
    Response.Write(cookieCheck.Value); 

    Response.Redirect(Request.Url.ToString()); 

} 

protected void Page_Load(object sender, EventArgs e) 
{ 

    HttpCookie preferredTheme = Request.Cookies.Get("PreferredTheme"); 

    if (preferredTheme == null) 
    { 
     Response.Write("PreferredTheme is null"); 
    } 

}

來源

2014-09-02 J S