Cookie的创建、读取、删除

创建Cookie:

HttpCookie 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);
  }