asp.net如何判断是否搜索引擎访问网站

    /// <summary>
    /// 判断是否为搜索引擎访问
    /// </summary>
    /// <param name="useragent"></param>
    /// <returns></returns>
    public bool IsSearchEngine(string useragent)
    {
        bool engine = false;
        if (!string.IsNullOrEmpty(useragent))
        {
            System.Text.RegularExpressions.Regex rx = new System.Text.RegularExpressions.Regex(@"Googlebot|Feedfetcher-Google|Baiduspider|Yahoo\s*\!\s*Slurp|YodaoBot|Sosoimagespider|Sosospider|Sogou\s*Web\s*Sprider", RegexOptions.IgnoreCase | RegexOptions.Compiled);
            engine = rx.IsMatch(useragent);
        }
        return engine;
    }

//使用方法
bool engine = IsSearchEngine(Request.ServerVariables["Http_User_Agent"]);
Response.Write(engine);