C# 后台请求Http

Http请求

 public static class HttpHelper
    {
        /// <summary>
        /// 获取返回结果http请求
        /// </summary>
        /// <param name="webRequest">webRequest对象</param>
        /// <returns>请求返回值</returns>
        public static string WebResponseGet(HttpWebRequest webRequest)
        {
            try
            {
                using (var httpWebResponse = (HttpWebResponse)webRequest.GetResponseAsync().Result)
                {
                    var stream = httpWebResponse.GetResponseStream();
                    if (stream == null) return null;
                    using (var responseReader = new StreamReader(stream, Encoding.UTF8))
                    {
                        return responseReader.ReadToEnd();
                    }
                }
            }
            catch (WebException wex)
            {
                var responseData = String.Empty;
                if (wex.Status == WebExceptionStatus.ProtocolError)
                {
                    try
                    {
                        var wexStream = wex.Response.GetResponseStream();
                        if (wexStream == null) return null;
                        using (StreamReader responseReader = new StreamReader(wexStream))
                        {
                            responseData = responseReader.ReadToEnd();
                        }
                    }
                    catch { }
                }
                if (!string.IsNullOrEmpty(responseData))
                {
                    return responseData;
                }
                throw;
            }
        }
        /// <summary>
        /// 同步方式发起http get请求
        /// </summary>
        /// <param name="url">请求URL</param>
        /// <param name="queryString">参数字符串</param>
        /// <returns>请求返回值</returns>
        public static string HttpGet(string url, string queryString = null)
        {
            if (!string.IsNullOrEmpty(queryString))
                url += "?" + queryString.Trim(' ', '?', '&');
            var webRequest = WebRequest.Create(url) as HttpWebRequest;
            if (webRequest == null) return null;
            webRequest.Method = "GET";
            webRequest.ContinueTimeout = 200000;
            return WebResponseGet(webRequest);
        }
        /// <summary>
        /// 同步方式发起http get请求
        /// </summary>
        /// <param name="url">请求URL</param>
        /// <param name="paras">请求参数列表</param>
        /// <returns>请求返回值</returns>
        public static string HttpGet(string url, Dictionary<string, string> paras)
        {
            var querystring = GetQueryFromParas(paras);
            return HttpGet(url, querystring);
        }
        /// <summary>
        /// 同步方式发起http post请求
        /// </summary>
        /// <param name="url">请求URL</param>
        /// <param name="queryString">参数字符串</param>
        /// <returns>请求返回值</returns>
        public static string HttpPost(string url, string queryString = null)
        {
            HttpWebRequest webRequest = WebRequest.Create(url) as HttpWebRequest;
            if (webRequest == null) return null;
            webRequest.Method = "POST";
            webRequest.ContentType = "application/x-www-form-urlencoded";
            webRequest.ContinueTimeout = 20000;
            //POST the data.
            using (var requestWriter = new StreamWriter(webRequest.GetRequestStreamAsync().Result))
            {
                requestWriter.Write(queryString);
            }
            return WebResponseGet(webRequest);
        }
        /// <summary>
        /// 同步方式发起http post请求
        /// </summary>
        /// <param name="url">请求URL</param>
        /// <param name="paras">请求参数列表</param>
        /// <returns>请求返回值</returns>
        public static string HttpPost(string url, Dictionary<string, string> paras)
        {
            var querystring = GetQueryFromParas(paras);
            return HttpPost(url, querystring);
        }
        /// <summary>
        /// 将Dictionary参数组合成字符串
        /// </summary>
        /// <param name="paras"></param>
        public static string GetQueryFromParas(Dictionary<string, string> paras)
        {
            if (paras == null || paras.Count == 0) return "";
            var buffer = new StringBuilder();
            var count = 1;
            foreach (var key in paras.Keys)
            {
                buffer.AppendFormat("{0}={1}", key, Uri.EscapeDataString(paras[key]));
                if (count < paras.Count)
                {
                    buffer.Append("&");
                }
                count++;
            }
            return buffer.ToString(); ;
        }
    }