public void Test()
        {
            var str = "System.Web.HttpUtility 对URL/HTML字符串进行编码";

            var s1 = System.Web.HttpUtility.UrlEncode(str);
            var s2 = System.Web.HttpUtility.UrlDecode(str);

            var html = "<input id=\"txtID\" type=\"hidden\">";

            var s3 = System.Web.HttpUtility.HtmlEncode(html);
            var s4 = System.Web.HttpUtility.HtmlDecode(html);
        }