C# Post请求

 String strURL = "Post请求地址";
            System.Net.HttpWebRequest request = (HttpWebRequest)WebRequest.Create(strURL);
            request.Method = "POST";
            HttpWebRequest.DefaultWebProxy = null;
            request.ContentType = "application/json;charset=utf-8";

            string data = "{\"key\":\"value\"}";

            byte[] param = System.Text.Encoding.UTF8.GetBytes(data);
            request.ContentLength = param.Length;
            System.IO.Stream writer = request.GetRequestStream();
            writer.Write(param, 0, param.Length);
            writer.Close();
            System.Net.HttpWebResponse response;
            try
            {
                response = (System.Net.HttpWebResponse)request.GetResponse();
            }
            catch (WebException ex)
            {
                response = (System.Net.HttpWebResponse)ex.Response;
            }

            System.IO.StreamReader myreader = new System.IO.StreamReader(response.GetResponseStream(), Encoding.UTF8);
            //返回的结果
            string strResult = myreader.ReadToEnd();
            myreader.Close();

通过base64加密：

string str = Convert.ToBase64String(System.Text.Encoding.UTF8.GetBytes(strJson));

来源：https://www.cnblogs.com/Alex-Mercer/p/12011063.html