/// <summary>

    /// 百度接口签名帮助类

    /// </summary>

    public class BaiduApiHelper

    {

        #region 构造函数

        /// <summary>

        /// 构造函数

        /// </summary>

        /// <param name="accessKeyId">百度AccessKeyId(AK)</param>

        /// <param name="secretAccessKey">百度SecretAccessKey(SK)</param>

        public BaiduApiHelper(string accessKeyId, string secretAccessKey)

        {

            _accessKeyId = accessKeyId;

            _secretAccessKey = secretAccessKey;

        }

        #endregion

        #region 内部成员 

        private string _accessKeyId { get; }

        private string _secretAccessKey { get; }

        private string UriEncode(string input, bool encodeSlash = false)

        {

            StringBuilder builder = new StringBuilder();

            foreach (byte b in Encoding.UTF8.GetBytes(input))

            {

                if ((b >= 'a' && b <= 'z') || (b >= 'A' && b <= 'Z') || (b >= '' && b <= '') || b == '_' || b == '-' || b == '~' || b == '.')

                {

                    builder.Append((char)b);

                }

                else if (b == '/')

                {

                    if (encodeSlash)

                    {

                        builder.Append("%2F");

                    }

                    else

                    {

                        builder.Append((char)b);

                    }

                }

                else

                {

                    builder.Append('%').Append(b.ToString("X2"));

                }

            }

            return builder.ToString();

        }

        private string Hex(byte[] data)

        {

            var sb = new StringBuilder();

            foreach (var b in data)

            {

                sb.Append(b.ToString("x2"));

            }

            return sb.ToString();

        }

        private string CanonicalRequest(HttpWebRequest req)

        {

            Uri uri = req.RequestUri;

            StringBuilder canonicalReq = new StringBuilder();

            canonicalReq.Append(req.Method).Append("\n").Append(UriEncode(Uri.UnescapeDataString(uri.AbsolutePath))).Append("\n");

            var parameters = HttpUtility.ParseQueryString(uri.Query);

            List<string> parameterStrings = new List<string>();

            foreach (KeyValuePair<string, string> entry in parameters)

            {

                parameterStrings.Add(UriEncode(entry.Key) + '=' + UriEncode(entry.Value));

            }

            parameterStrings.Sort();

            canonicalReq.Append(string.Join("&", parameterStrings.ToArray())).Append("\n");

            string host = uri.Host;

            if (!(uri.Scheme == "https" && uri.Port == ) && !(uri.Scheme == "http" && uri.Port == ))

            {

                host += ":" + uri.Port;

            }

            canonicalReq.Append("host:" + UriEncode(host));

            return canonicalReq.ToString();

        }

        #endregion

        #region 外部接口

        /// <summary>

        /// 发送POST请求

        /// </summary>

        /// <param name="method">请求方法，需要大写，列如(POST)</param>

        /// <param name="host">主机地址列如(http://sms.bj.baidubce.com)</param>

        /// <param name="url">接口地址列如(/bce/v2/message)</param>

        /// <param name="paramters">参数列表</param>

        /// <returns></returns>

        public string RequestData(string method, string host, string url, Dictionary<string, object> paramters = null)

        {

            string ak = _accessKeyId;

            string sk = _secretAccessKey;

            DateTime now = DateTime.Now;

            int expirationInSeconds = ;

            HttpWebRequest req = WebRequest.Create(host + url) as HttpWebRequest;

            Uri uri = req.RequestUri;

            req.Method = method;

            req.ContentType = "application/json";

            if (paramters != null)

            {

                Stream requestStream = req.GetRequestStream();

                byte[] data = Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(paramters));

                requestStream.Write(data, , data.Length);

            }

            string signDate = now.ToUniversalTime().ToString("yyyy'-'MM'-'dd'T'HH':'mm':'ssK");

            string authString = "bce-auth-v1/" + ak + "/" + signDate + "/" + expirationInSeconds;

            string signingKey = Hex(new HMACSHA256(Encoding.UTF8.GetBytes(sk)).ComputeHash(Encoding.UTF8.GetBytes(authString)));

            string canonicalRequestString = CanonicalRequest(req);

            string signature = Hex(new HMACSHA256(Encoding.UTF8.GetBytes(signingKey)).ComputeHash(Encoding.UTF8.GetBytes(canonicalRequestString)));

            string authorization = authString + "/host/" + signature;

            req.Headers.Add("x-bce-date", signDate);

            req.Headers.Add(HttpRequestHeader.Authorization, authorization);

            HttpWebResponse res;

            string message = "";

            try

            {

                res = req.GetResponse() as HttpWebResponse;

            }

            catch (WebException e)

            {

                res = e.Response as HttpWebResponse;

            }

            message = new StreamReader(res.GetResponseStream()).ReadToEnd();

            return message;

        }

        /// <summary>

        /// 发送短信

        /// </summary>

        /// <param name="phoneNum">手机号码</param>

        /// <param name="code">验证码</param>

        /// <returns></returns>

        public static bool SendMsg(string phoneNum, string code)

        {

            try

            {

                BaiduApiHelper baiduApiHelper = new BaiduApiHelper("", "");

                string host = "http://sms.bj.baidubce.com";

                string url = "/bce/v2/message";

                Dictionary<string, object> paramters = new Dictionary<string, object>();

                paramters.Add("invokeId", "Vhn0B-vCXn-8888");

                paramters.Add("phoneNumber", phoneNum);

                paramters.Add("templateCode", "smsTpl:e747612888e9018888");

                paramters.Add("contentVar", new { code = code });

                string resJsonStr = baiduApiHelper.RequestData("POST", host, url, paramters);

                var resJson = JsonConvert.DeserializeObject<JObject>(resJsonStr);

                return resJson["code"]?.ToString() == "";

            }

            catch

            {

                return false;

            }

        }

        #endregion

    }