cs端调用webApi

 public class Httphelper
     {
         public static string Post1(string url, string postString)
         {

             using (WebClient webClient = new WebClient())
             {
                 byte[] postData = Encoding.UTF8.GetBytes(postString);//编码，
                 webClient.Headers.Add("Content-Type", "application/json");//采取POST方式必须加的header，如果改为GET方式的话就去掉这句话即可
                 byte[] responseData = webClient.UploadData(url, "POST", postData);//得到返回字符流
                 string srcString = Encoding.UTF8.GetString(responseData);//解码
                 return srcString;
             }
         }

         public static string Post(string url, string postData)
         {
             string result = "";

             HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);

             req.Method = "POST";

             req.ContentType = "application/json";

             byte[] data = Encoding.UTF8.GetBytes(postData);

             req.ContentLength = data.Length;
             //req.Timeout = 30000;
             using (Stream reqStream = req.GetRequestStream())
             {
                 reqStream.Write(data, , data.Length);

                 reqStream.Close();
             }

             HttpWebResponse resp = (HttpWebResponse)req.GetResponse();

             Stream stream = resp.GetResponseStream();

             //获取响应内容
             using (StreamReader reader = new StreamReader(stream, Encoding.UTF8))
             {
                 result = reader.ReadToEnd();
             }

             return result;
         }
     }

HttpClient 调用

  /// <summary>
         /// post 同步
         /// </summary>
         /// <param name="url"></param>
         /// <param name="postString"></param>
         /// <returns></returns>
         public static string Post(string url, string postData)
         {
             try
             {
                 using (HttpClient _httpClient = new HttpClient())
                 {
                     StringContent httpClient = new StringContent(postData, Encoding.UTF8, "application/json");
                     var response = _httpClient.PostAsync(url, httpClient).Result;
                     string jsonstr = response.Content.ReadAsStringAsync().Result;
                     return jsonstr;
                 }
             }
             catch (Exception ex)
             {
                 _logger.LogError(string.Format("Api调用异常--url【{0}】,参数【{1}】", url, postData), ex);
                 return "";
             }
         }
         /// <summary>
         /// post 异步
         /// </summary>
         /// <param name="url"></param>
         /// <param name="postData"></param>
         /// <returns></returns>
         public static async void PostAsync(string url, string postData)
         {
             try
             {
                 using (HttpClient _httpClient = new HttpClient())
                 {
                     StringContent httpClient = new StringContent(postData, Encoding.UTF8, "application/json");
                     var response = await _httpClient.PostAsync(url, httpClient);
                     string jsonstr = await response.Content.ReadAsStringAsync();
                 }
             }
             catch (Exception ex)
             {
                 _logger.LogError(string.Format("Api调用异常--url【{0}】,参数【{1}】", url, postData), ex);
             }
         }