创建Cookie:
HttpCookie cookie = new cookie = new HttpCookie(COOKIE_NAME_FOR_USER);
cookie.Expires = DateTime.Now.AddYears(1);//设置日期
cookie[COOKIE_USER_NAME] = "用户名";
System.Web.HttpContext.Current.Response.Cookies.Add(cookie);
读取Cookie:
HttpCookie cookie = System.Web.HttpContext.Current.Request.Cookies.Get(COOKIE_NAME_FOR_USER);
删除Cookie：
System.Web.HttpContext.Current.Request.Cookies.Remove(COOKIE_NAME_FOR_USER)
另外，判断是否有cookie可以直接使用取的cookie和null进行比较，如果取出来非null就说明不为空
另外在一般处理程序中的使用方法：
//写入cookie
HttpCookie hc = new HttpCookie("time");
hc.Value = DateTime.Now.ToString();
hc.Expires = DateTime.Now.AddDays(7);
context.Response.Cookies.Add(hc);
//读取Cookie
HttpCookie hc = context.Request.Cookies["time"]; if (hc != null) { context.Response.Write(hc.Value); } else { context.Response.Write("meiyou "); }
//删除cookie 就是把cookie设置过期输出
int count = context.Request.Cookies.Count;
for (int i = 0; i < count; i++)
{
HttpCookie hc = context.Request.Cookies[i];
hc.Expires = DateTime.Now.AddDays(-1); //设置过期
context.Response.Cookies.Add(hc);
}
原文：http://www.cnblogs.com/xbblogs/p/4721476.html