騰訊雲圖片鑒黃集成到C#

官方文檔：https://cloud.tencent.com/document/product/641/12422

請求官方API及簽名的生成代碼如下：

    public class TencentCloundPicHelper
    {
        /// <summary>
        /// 發送Post請求騰訊雲
        /// </summary>
        public string SendPost(string postDataStr)
        {
            var url = @"http://service.image.myqcloud.com/detection/porn_detect";

            try
            {
                System.Net.ServicePointManager.Expect100Continue = false;
                var request = (HttpWebRequest)HttpWebRequest.Create(url);
                
                request.Method = "POST";
                
                SetHeaderValue(request.Headers, "content-type", "application/json");
                SetHeaderValue(request.Headers, "content-length", postDataStr.Length.ToString());
                SetHeaderValue(request.Headers, "Host", "service.image.myqcloud.com");
                SetHeaderValue(request.Headers, "authorization", GetSign());
                var memStream = new MemoryStream();
                
                var jsonByte = Encoding.GetEncoding("utf-8").GetBytes(postDataStr);
                memStream.Write(jsonByte, 0, jsonByte.Length);

                request.ContentLength = memStream.Length;
                var requestStream = request.GetRequestStream();
                memStream.Position = 0;
                var tempBuffer = new byte[memStream.Length];
                memStream.Read(tempBuffer, 0, tempBuffer.Length);
                memStream.Close();

                requestStream.Write(tempBuffer, 0, tempBuffer.Length);
                requestStream.Close();

                var response = request.GetResponse();
                using (var s = response.GetResponseStream())
                {
                    var reader = new StreamReader(s, Encoding.UTF8);
                    return reader.ReadToEnd();
                }
            }
            catch (WebException we)
            {
                if (we.Status == WebExceptionStatus.ProtocolError)
                {
                    using (var s = we.Response.GetResponseStream())
                    {
                        var reader = new StreamReader(s, Encoding.UTF8);
                        return reader.ReadToEnd();
                    }
                }
                else
                {
                    throw we;
                }
            }
            catch (Exception e)
            {
                throw e;
            }
        }

        /// <summary>
        /// 獲取簽名
        /// </summary>
        public static string GetSign()
        {
            var appId = ConfigurationManager.AppSettings["AppId"];//開發者的 APPID，接入智能圖像時由系統生成
            var bucket = "tengxunyun";//Bucket，空間名稱，即圖片資源的組織管理單元
            var secretId = ConfigurationManager.AppSettings["SecretId"];//Secret ID
            var secretKey = ConfigurationManager.AppSettings["SecretKey"];//secretKey
            var ts = DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, 0);
            var currentTime = Convert.ToInt64(ts.TotalSeconds);//當前時間戳，是一個符合 UNIX Epoch 時間戳規範的數值，單位為秒，多次簽名時，e 應大於 t
            var expiredTime = Convert.ToInt64((DateTime.UtcNow.AddMinutes(180) - new DateTime(1970, 1, 1, 0, 0, 0, 0)).TotalSeconds);//簽名的有效期，是一個符合 UNIX Epoch 時間戳規範的數值，單位為秒；單次簽名時，e 必須設置為 0
            var rand = GetRandom();//隨機串，無符號 10 進位整數，用戶需自行生成，最長 10 位
            var userid = 0;//歷史遺留欄位，請填寫為 0
            var fileid = "";//資源存儲的唯一標識，單次簽名必填；多次簽名選填，如填寫則會驗證與當前操作的文件路徑是否一致。
            var encryptText = $"a={appId}&b={bucket}&k={secretId}&e={expiredTime}&t={currentTime}&r={rand}&u=0&f=";
            var sign = Hmacsha1Encrypt(encryptText, secretKey);

            return sign;
        }

        /// <summary>
        /// 設置Http post請求頭
        /// </summary>
        public static void SetHeaderValue(WebHeaderCollection header, string name, string value)
        {
            var property = typeof(WebHeaderCollection).GetProperty("InnerCollection", BindingFlags.Instance | BindingFlags.NonPublic);
            if (property != null)
            {
                var collection = property.GetValue(header, null) as NameValueCollection;
                collection[name] = value;
            }
        }

        /// <summary>
        /// HMACSHA1演算法加密
        /// </summary>
        private static string Hmacsha1Encrypt(string encryptText, string encryptKey)
        {
            using (HMACSHA1 mac = new HMACSHA1(Encoding.UTF8.GetBytes(encryptKey)))
            {
                var hash = mac.ComputeHash(Encoding.UTF8.GetBytes(encryptText));
                var pText = Encoding.UTF8.GetBytes(encryptText);
                var all = new byte[hash.Length + pText.Length];
                Array.Copy(hash, 0, all, 0, hash.Length);
                Array.Copy(pText, 0, all, hash.Length, pText.Length);
                return Convert.ToBase64String(all);
            }
        }

        /// <summary>
        /// 獲取隨機數
        /// </summary>
        private static int GetRandom()
        {
            var random = new Random();
            var rand = random.Next(10000, 999999999);
            return rand;
        }
    }