winform端程式碼：

public static string PostImageData(string url, IDictionary<string, string> parameters, int timeout, string userAgent, CookieCollection cookies)
        {
            System.GC.Collect();//垃圾回收，回收沒有正常關閉的http連線
            string result = "";
            HttpWebRequest request = null;
            HttpWebResponse response = null;
            //如果是傳送HTTPS請求  
            if (url.StartsWith("https", StringComparison.OrdinalIgnoreCase))
            {
                request = WebRequest.Create(url) as HttpWebRequest;
            }
            else
            {
                // request = WebRequest.Create(url) as HttpWebRequest;
                request = (HttpWebRequest)WebRequest.Create(url);
            }
            request.Method = "POST";
            request.ContentType = "application/x-www-form-urlencoded";
            //request.ContentLength = data.Length;
            //設定代理UserAgent和超時
            //request.UserAgent = userAgent;
            //request.Timeout = timeout;

            if (cookies != null)
            {
                request.CookieContainer = new CookieContainer();
                request.CookieContainer.Add(cookies);
            }
            //傳送POST資料  
            if (!(parameters == null || parameters.Count == 0))
            {
                StringBuilder buffer = new StringBuilder();
                int i = 0;
                foreach (string key in parameters.Keys)
                {
                    if (i > 0)
                    {
                        buffer.AppendFormat("&{0}={1}", key, parameters[key]);
                    }
                    else
                    {
                        buffer.AppendFormat("{0}={1}", key, parameters[key]);
                        i++;
                    }
                }

                byte[] data = Encoding.ASCII.GetBytes(buffer.ToString());
                request.ContentLength = data.Length;
                using (Stream stream = request.GetRequestStream())
                {
                    stream.Write(data, 0, data.Length);
                    stream.Close();
                }
 
                //獲取服務端返回
                response = (HttpWebResponse)request.GetResponse();

                //獲取服務端返回資料
                StreamReader sr = new StreamReader(response.GetResponseStream(), Encoding.UTF8);
                result = sr.ReadToEnd().Trim();
                sr.Close();

            }
            string[] values = request.Headers.GetValues("Content-Type");

            return result;
        }
 

                string url = "http://127.0.0.1:5000/upload";
                IDictionary<string, string> parameters = new Dictionary<string, string>();
                byte[] byteData = GetPictureData(m_filepath);
                string picStr = Convert.ToBase64String(byteData);
                parameters.Add("picStr", picStr);
                string mes = HttpService.PostImageData(url, parameters, 3000, null, null);
                label_message.Text = mes;
 

flask端程式碼：

@app.route('/upload', methods=['POST'])
def upload():
    #upload_file = request.files["picture"]
    # imgdata = base64.b64decode(upload_file)
    # file = open('1.jpg', 'wb')
    # file.write(imgdata)
    # file.close()
    upload_file = request.form.get("picStr")
    upload_file =  urllib.parse.quote_plus(upload_file, safe="/=")
    # upload_file = bytes(upload_file, encoding="utf8")
    imgdata = base64.b64decode(upload_file)
    print(len(imgdata))
    global savePath
    savePath = os.getcwd() + "/upload/" + str(uuid.uuid1()) + ".jpg"
    print(savePath)
    file = open(savePath, 'wb')
    file.write(imgdata)
    file.close()
    # img_array = np.fromstring(imgdata, np.uint8)  # 轉換np序列
    # img = cv2.imdecode(img_array, cv2.COLOR_BGR2RGB)  # 轉換Opencv格式
    #cv2.imwrite('4.jpg', img)
    return "圖片上傳成功！"