1.在使用HttpClient 的時候需要引用system.net.http;
2.system.net.http引用是.net4.5框架引入的一個方式，所以使用的時候要確保專案是.net 4.5 或更高版本

1. 程式碼如下：

    static void Main(string[] args)
   {
       httpclient();
   }
     public static void httpclient()
   {
       HttpClient client = new HttpClient();
       client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
       string url = "http://192.168.0.86:8585/gsa/tool/es/selAndImportData";
       var json = "{\"dataSource\":\"Data Source=(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=192.168.0.70)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=orcl70)));User ID=sde;Password=sde;Unicode=True\",\"type\":\"0\",\"whereCondition\":\"dlwz='國和百壽一村6號'\",\"tableName\":\"hzdzd_pt\"}";
   
   
     //  var json = "{ \"dataSource\": \"Data Source=(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=192.168.0.70)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=orcl70)));User ID=sde;Password=sde;Unicode=True\" }";
       var httpContent = new StringContent(json, Encoding.UTF8);
       httpContent.Headers.ContentType = new MediaTypeHeaderValue("application/json");
       var response = client.PostAsync(url, httpContent).Result;
       Console.WriteLine(response.Content);
       if (!response.IsSuccessStatusCode)
       {
           Console.WriteLine(response.StatusCode);
           Console.ReadLine();
           //Response (string.Format("{0} ({1})", (int)response.StatusCode, response.ReasonPhrase));
       }
   }