/// <summary>
 /// GET异步请求
 /// </summary>
 /// <typeparam name="T"></typeparam>
 /// <param name="url"></param>
 /// <param name="httpDelegate">委托</param>
 /// <param name="t"></param>
 /// <param name="header"></param>
 /// <param name="encoding"></param>
 public static void getAsync <T>(string url, httpCallBackDelegate httpDelegate, T t = null, Dictionary <string, string> header = null, string encoding = "utf-8") where T : class
 {
     try
     {
         //添加必要的头
         httpClient.DefaultRequestHeaders.Add("UserAgent", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.57 Safari/537.36");
         if (header != null)
         {
             foreach (var x in header)
             {
                 httpClient.DefaultRequestHeaders.Add(x.Key, x.Value);
             }
         }
         //链接参数
         if (t != null)
         {
             if (url.Contains("?"))
             {
                 url += $"&{ModelHelper.convertToUrlParameter(t)}";
             }
             else
             {
                 url += $"?{ModelHelper.convertToUrlParameter(t)}";
             }
         }
         //请求
         httpClient.GetAsync(url).ContinueWith((task) =>
         {
             HttpResponseMessage response = task.Result;
             // 确认响应成功,否则抛出异常
             response.EnsureSuccessStatusCode();
             // 异步读取响应为字符串
             response.Content.ReadAsStringAsync().ContinueWith(
                 (readTask) =>
             {
                 var ret = readTask.Result;
                 //响应委托任务
                 httpDelegate(ret);
             });
         });
     }
     catch (HttpRequestException ex)
     {
         throw new Exception(ex.Message);
     }
 }
        /// <summary>
        /// 异步POST
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="url"></param>
        /// <param name="httpDelegate">委托</param>
        /// <param name="t"></param>
        /// <param name="header"></param>
        /// <param name="encoding"></param>
        public static void postAsync <T>(string url, httpCallBackDelegate httpDelegate, T t = null, Dictionary <string, string> header = null, string encoding = "utf-8") where T : class
        {
            try
            {
                //添加必要的头
                httpClient.DefaultRequestHeaders.Add("Method", "Post");
                httpClient.DefaultRequestHeaders.Add("KeepAlive", "false");
                httpClient.DefaultRequestHeaders.Add("UserAgent", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.57 Safari/537.36");
                if (header != null)
                {
                    foreach (var x in header)
                    {
                        httpClient.DefaultRequestHeaders.Add(x.Key, x.Value);
                    }
                }
                //将对象序列化成字典
                var dic = ModelHelper.convertToDictionary(t);

                HttpContent content = new FormUrlEncodedContent(dic);
                httpClient.PostAsync(url, content).ContinueWith((task) =>
                {
                    HttpResponseMessage response = task.Result;
                    // 确认响应成功,否则抛出异常
                    response.EnsureSuccessStatusCode();
                    // 异步读取响应为字符串
                    var contentType = response.Content.Headers.ContentType;
                    if (string.IsNullOrEmpty(contentType.CharSet))
                    {
                        contentType.CharSet = encoding;
                    }
                    response.Content.ReadAsStringAsync().ContinueWith(
                        (readTask) =>
                    {
                        var ret = readTask.Result;
                        //响应委托任务
                        httpDelegate(ret);
                    });
                });
            }
            catch (HttpRequestException ex)
            {
                throw new Exception(ex.Message);
            }
        }