//判断webService是否可以使用

  public bool webservice(string url)
        {
            try
            {
                string uri = url + "?wsdl";
                HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);

                request.UseDefaultCredentials = true;
                request.Method = "GET";
                request.Timeout = 5000;
                HttpWebResponse response = (HttpWebResponse)request.GetResponse();
                if (response.StatusCode == HttpStatusCode.OK && response.ContentType.Substring(0, 8) == "text/xml")
                {
                    return true;
                }
                else
                {
                    return false;
                }
            }
            catch (WebException e)
            {
                System.Diagnostics.Trace.Write(e.Message);
                return false;
            }
        }

调用该方法：

  string url = "http://192.168.1.99:8080/hyqdxt/getOnlineList";//调用webService地址
            bool falg = webservice(url);
            //检查连接webservicesi
            if (falg == true)
            {
                MessageBox.Show("可以使用");
            }else{
                MessageBox.Show("不可使用");
            }