WebClient请求帮助类

/// <summary>
    /// 通过JSON方式发送POST请求
    /// 将返回结果按JSON方式解析
    /// </summary>
    public static class WebClientHelper
    {
        const string REQUEST_HEADER_BEARER = "bearer";

        /// <summary>
        /// 通过POST方式调用WEB API
        /// 期待返回值为JSON字符串，并自动转换为期望的对象类型
        /// 如果想直接获得原始的返回字符串，则T传为string
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="url"></param>
        /// <param name="postData">post数据。自动转换为json格式，可以为空</param>
        /// <param name="accessToken">调用FIDP API时，需要填写Access Token</param>
        /// <returns></returns>
        public static T Post<T>(string url, object postData, bool bNeedToken = true) where T : class
        {
            string accessToken = bNeedToken ? TokenCache.GetAccessToken() : null;
            using (var wc = MyWebClient(accessToken))
            {
                string postJson = string.Empty;
                if (postData != null) postJson = JsonConvert.SerializeObject(postData);

                string response = wc.UploadString(url, postJson);
                if (typeof(T) == typeof(string)) return response as T;
                T ret = Newtonsoft.Json.JsonConvert.DeserializeObject<T>(response);

                return ret;
            }
        }

        /// <summary>
        /// POST的异步版本
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="url"></param>
        /// <param name="postData"></param>
        /// <param name="accessToken"></param>
        /// <returns></returns>
        public static async Task<T> PostAsync<T>(string url, object postData, bool bNeedToken = true) where T : class
        {
            string accessToken = bNeedToken ? TokenCache.GetAccessToken() : null;
            using (var wc = MyWebClient(accessToken))
            {
                string postJson = string.Empty;
                if (postData != null) postJson = JsonConvert.SerializeObject(postData);

                string response = await wc.UploadStringTaskAsync(url, postJson);
                if (typeof(T) == typeof(string)) return response as T;

                T ret = JsonConvert.DeserializeObject<T>(response);

                return ret;

                
            }
        }


        /// <summary>
        /// 通过GET方式调用WEB API
        /// 期待返回值为JSON字符串，并自动转换为期望的对象类型
        /// 如果想直接获得原始的返回字符串，则T传为string
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="url"></param>
        /// <param name="accessToken"></param>
        /// <returns></returns>
        public static T Get<T>(string url, bool bNeedToken = true) where T : class
        {
            string accessToken = bNeedToken ? TokenCache.GetAccessToken() : null;
            using (var wc = MyWebClient(accessToken))
            {
                string response = wc.DownloadString(url);

                if (typeof(T) == typeof(string)) return response as T;

                T ret = JsonConvert.DeserializeObject<T>(response);

                return ret;
            }
        }


        public static string Get(string url, bool bNeedToken = true)
        {
            string accessToken = bNeedToken ? TokenCache.GetAccessToken() : null;
            using (var wc = MyWebClient(accessToken))
            {
                string response = wc.DownloadString(url);
                return response;
            }
        }


        /// <summary>
        /// GET的异步版本
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="url"></param>
        /// <param name="accessToken"></param>
        /// <returns></returns>
        public static async Task<T> GetAsync<T>(string url, bool bNeedToken = true) where T : class
        {
            string accessToken = bNeedToken ? TokenCache.GetAccessToken() : null;
            using (var wc = MyWebClient(accessToken))
            {
                string response = await wc.DownloadStringTaskAsync(url);

                if (typeof(T) == typeof(string)) return response as T;

                T ret = JsonConvert.DeserializeObject<T>(response);

                return ret;
            }
        }

        private static WebClient MyWebClient(string accessToken)
        {
            var wc = new WebClient { Encoding = Encoding.UTF8 };

            wc.Headers.Add(HttpRequestHeader.ContentType, "application/json; charset=utf-8");
            wc.Headers.Add(HttpRequestHeader.Accept, "*/*");
            wc.Headers.Add(HttpRequestHeader.AcceptCharset, "ISO-8859-1,utf-8;q=0.7,*;q=0.7");
            if (!string.IsNullOrEmpty(accessToken)) wc.Headers.Add(HttpRequestHeader.Authorization, REQUEST_HEADER_BEARER + " " + accessToken);

            return wc;
        }

        /// <summary>
        /// 上传文件
        /// </summary>
        /// <param name="url"></param>
        /// <param name="file"></param>
        /// <param name="bNeedToken"></param>
        /// <returns></returns>
        public static string UploadFile(string url, string file, bool bNeedToken = false)
        {
            string accessToken = bNeedToken ? TokenCache.GetAccessToken() : null;
            using (var wc = MyWebClient(accessToken))
            {
                var b = wc.UploadFile(url, file);
                return Encoding.UTF8.GetString(b);
            }
        }

    }

public class TokenCache 
    {
        static TokenInfo tokenInfo = new TokenInfo();
        static JwtCore jwtCore = new JwtCore();

        static ICacheManager<TokenInfo> accessTokenCache = CacheFactory.FromConfiguration<TokenInfo>("tokenCache");
        
        /// <summary>
        /// SSO Clock Skew（秒）:时钟调整，适配不同服务器之间的时钟偏差
        /// </summary>
        static readonly int CLOCK_SKEW_IN_SECONDS = int.Parse(ConfigurationManager.AppSettings["SSO:CLOCK_SKEW_IN_SECONDS"]);

        /// <summary>
        /// AppInfo
        /// </summary>
        static readonly string AppId = ConfigurationManager.AppSettings["AppId"];
        static readonly string AppSecret = ConfigurationManager.AppSettings["AppSecret"];
        static public string GetAccessToken()
        {
            lock(tokenInfo)
            {
                return getAccessToken();
            }
        }

        static string getAccessToken()
        {
            string tokenKey = AppId;

            var ti = accessTokenCache.Get(tokenKey);
            if(ti != null)
            {
                return ti.Token;
            }

            // request a new access-token
            string urlAccessToken = ApiConfig.Instance.GetUrl("sso.access_token");
            Debug.Assert(!string.IsNullOrEmpty(urlAccessToken));
            SSOAccessTokenReq req = new SSOAccessTokenReq()
            {
                AppId = AppId,
                AppSecret = AppSecret,
                //StoreCode,UserCode
            };

            //try
            {
                var ret = WebClientHelper.Post<ApiResultT<string>>(urlAccessToken, req, false);
                if (ret.IsSuccess())
                {
                    JwtPayload jwtPayload;

                    var ret2 = jwtCore.ValidateToken(ret.data, out jwtPayload);
                    if (ret2.IsSuccess())
                    {
                        tokenInfo.Token = ret.data;
                        tokenInfo.ExpireAt = jwtPayload.exp;

                        accessTokenCache.Add(tokenKey, tokenInfo);

                        return tokenInfo.Token;
                    }
                    throw new Exception("Access Token 无效：" + ret2.ToString());
                }

                throw new Exception("获取Access Token失败：" + ret.ToString());
            }
            //catch(WebException ex)
            //{
            //    HttpWebResponse httpRep = ex.Response as HttpWebResponse;
            //    if (httpRep != null)
            //    {
            //        if(httpRep.StatusCode == HttpStatusCode.Forbidden)
            //        {

            //        }

            //    }
            //}

        }

        internal class TokenInfo
        {
            public string Token { get; set; }

            /// <summary>
            /// 到期时间：Unix Timestamp
            /// </summary>
            public long ExpireAt { get; set; }
        }    
    
    }