根据UserAgent 获取操作系统名称

/// <summary>
        /// 根据 User Agent 获取操作系统名称
        /// </summary>
        private static string GetOsName(string userAgent)
        {
            string osVersion = "Unknown";
            if (string.IsNullOrEmpty(userAgent))
            {
                return osVersion;
            }

if (userAgent.Contains("Windows NT 6.1"))
            {
                osVersion = "Windows 7";
            }
            else if (userAgent.Contains("Windows NT 6.0"))
            {
                osVersion = "Windows Vista/Server 2008";
            }
            else if (userAgent.Contains("Windows NT 5.2"))
            {
                osVersion = "Windows Server 2003";
            }
            else if (userAgent.Contains("Windows NT 5.1"))
            {
                osVersion = "Windows XP";
            }
            else if (userAgent.Contains("Windows NT 5"))
            {
                osVersion = "Windows 2000";
            }
            else if (userAgent.Contains("Windows NT 4"))
            {
                osVersion = "Windows NT4";
            }
            else if (userAgent.Contains("Windows Me"))
            {
                osVersion = "Windows Me";
            }
            else if (userAgent.Contains("Windows 98"))
            {
                osVersion = "Windows 98";
            }
            else if (userAgent.Contains("Windows 95"))
            {
                osVersion = "Windows 95";
            }
            else if (userAgent.Contains("Windows"))
            {
                osVersion = "Windows";
            }
            else if (userAgent.Contains("Mac"))
            {
                osVersion = "Mac";
            }
            else if (userAgent.Contains("Unix"))
            {
                osVersion = "UNIX";
            }
            else if (userAgent.Contains("Linux"))
            {
                osVersion = "Linux";
            }
            else if (userAgent.Contains("SunOS"))
            {
                osVersion = "SunOS";
            }
            return osVersion;
        }