POST请求，FileStream转换成Stream

        /// <summary>
        /// POST请求
        /// </summary>
        /// <param name="url"></param>
        /// <param name="payload">参数字符串</param>
        /// <returns></returns>
        public static string Post(byte[] payload)
        {
            payload = new byte[] { };
            payload = QunarPolicyUtils.ReadFile("d:\\test.zip");

            string url = "";
            //创建post请求
            HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
            request.Method = "POST";//请求方式post
            request.ContentType = "multipart/form-data;charset=utf-8";//链接类型   multipart/form-data
            //byte[] payload = Encoding.UTF8.GetBytes(param);//参数编码
            request.ContentLength = payload.Length;

            //发送post的请求,写入参数
            Stream writer = request.GetRequestStream();
            writer.Write(payload, 0, payload.Length);
            writer.Close();

            //接受返回来的数据
            HttpWebResponse response = request.GetResponse() as HttpWebResponse;
            Stream stream = response.GetResponseStream();
            StreamReader reader = new StreamReader(stream, Encoding.UTF8);
            string value = reader.ReadToEnd();

            reader.Close();
            stream.Close();
            response.Close();

            return value;
        }

        /// <summary>
        /// POST请求
        /// </summary>
        /// <param name="payload"></param>
        public static string PostXML(byte[] payload)
        {
            payload = new byte[] { };
            payload = QunarPolicyUtils.ReadFile("d:\\test.zip");
            //发送请求
            var request = (HttpWebRequest)WebRequest.Create("");
            request.Method = "POST";
            request.ContentType = "application/json;charset=UTF-8";
            var length = payload.Length;
            request.ContentLength = length;
            var writer = request.GetRequestStream();
            writer.Write(payload, 0, length);
            writer.Close();

            //接收数据
            var response = (HttpWebResponse)request.GetResponse();
            var responseString = new StreamReader(response.GetResponseStream(), Encoding.GetEncoding("utf-8")).ReadToEnd();
            return responseString;
        }

        /// <summary>
        /// POST请求
        /// </summary>
        /// <param name="payload"></param>
        /// <returns></returns>
        public static string PostByte(byte[] payload)
        {
            payload = new byte[] { };
            payload = QunarPolicyUtils.ReadFile("d:\\test.zip");
            HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create("");
            req.Method = "POST";
            req.ContentType = "mutipart/form-data";
            req.ContentLength = payload.Length;
            var r = req.GetRequestStream();

            using (Stream reqstream = req.GetRequestStream())
            {
                reqstream.Write(payload, 0, (int)req.ContentLength);
            }
            HttpWebResponse responstream = (HttpWebResponse)req.GetResponse();
            var redstr = new StreamReader(responstream.GetResponseStream()).ReadToEnd();
            return redstr;

        }

        /// <summary>
        /// Stream转换成FileStream
        /// </summary>
        /// <param name="stream"></param>
        /// <param name="fileName"></param>
        public static void StreamToFile(Stream stream, string fileName)
        {
            stream.Position = 0;
            // 把 Stream 转换成 byte[] 
            byte[] bytes = new byte[stream.Length];
            stream.Read(bytes, 0, bytes.Length);
            // 设置当前流的位置为流的开始 
            stream.Seek(0, SeekOrigin.Begin);

            // 把 byte[] 写入文件       
            using (FileStream fs = new FileStream(fileName, FileMode.Create))
            {
                using (BinaryWriter bw = new BinaryWriter(fs))
                {
                    bw.Write(bytes);
                    bw.Close();
                    fs.Close();
                }
            }
        }

        /// <summary>
        /// FileStream转换成Stream
        /// </summary>
        /// <param name="fileName"></param>
        /// <returns></returns>
        public static Stream FileToStream(string fileName)
        {
            // 打开文件 
            using (FileStream fileStream = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.Read))
            {
                // 读取文件的 byte[]
                byte[] bytes = new byte[fileStream.Length];
                fileStream.Read(bytes, 0, bytes.Length);
                fileStream.Close();
                // 把 byte[] 转换成 Stream
                Stream stream = new MemoryStream(bytes);
                return stream;
            }
        }

        /// <summary>
        /// FileStream转换成byte[]
        /// </summary>
        /// <param name="fileName"></param>
        /// <returns></returns>
        public static byte[] ReadFile(string fileName)
        {
            using (FileStream fs = new FileStream(fileName, FileMode.OpenOrCreate))
            {
                byte[] buffer = new byte[fs.Length];
                try
                {
                    fs.Read(buffer, 0, buffer.Length);
                    fs.Seek(0, SeekOrigin.Begin);
                    return buffer;
                }
                catch
                {
                    return buffer;
                }
                finally
                {
                    if (fs != null)
                        fs.Close();
                }
            }
        }