string jsonContent = JsonConvert.SerializeObject(args);
 using(var clientUrl = new HttpClient())
 {
     var token = "token的值";
     // 法①
     clientUrl.DefaultRequestHeaders.Add("token", token);
     var data = new StringContent(jsonContent, Encoding.UTF8, "application/json");
     result = clientUrl.PostAsync(url, data).Result.Content.ReadAsStringAsync().Result;
   
     // 法②
     var data = new StringContent(jsonContent, Encoding.UTF8, "application/json");
     data.Headers.Add("token", token);
     result = clientUrl.PostAsync(url, data).Result.Content.ReadAsStringAsync().Result;
 }