http://blog.csdn.net/hellowjwang/article/details/19975635 public class HttpPost    {        /// 
        /// 以Post 形式提交数据到 uri        /// 
        ///         ///         ///         /// 
             public static byte[] Post(Uri uri, IEnumerable
     
       files, NameValueCollection values)        {            string boundary = "----------------------------" + DateTime.Now.Ticks.ToString("x");            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);            request.ContentType = "multipart/form-data; boundary=" + boundary;            request.Method = "POST";            request.KeepAlive = true;            request.Credentials = CredentialCache.DefaultCredentials;            MemoryStream stream = new MemoryStream();            byte[] line = Encoding.ASCII.GetBytes("\r\n--" + boundary + "\r\n");            //提交文本字段            if (values != null)            {                string format = "\r\n--" + boundary + "\r\nContent-Disposition: form-data; name=\"{0}\";\r\n\r\n{1}";                foreach (string key in values.Keys)                {                    string s = string.Format(format, key, values[key]);                    byte[] data = Encoding.UTF8.GetBytes(s);                    stream.Write(data, 0, data.Length);                }                stream.Write(line, 0, line.Length);            }            //提交文件            if (files != null)            {                string fformat = "Content-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"\r\n Content-Type: application/octet-stream\r\n\r\n";                foreach (UploadFile file in files)                {                    string s = string.Format(fformat, file.Name, file.Filename);                    byte[] data = Encoding.UTF8.GetBytes(s);                    stream.Write(data, 0, data.Length);                    stream.Write(file.Data, 0, file.Data.Length);                    stream.Write(line, 0, line.Length);                }            }            request.ContentLength = stream.Length;            Stream requestStream = request.GetRequestStream();            stream.Position = 0L;            stream.CopyTo(requestStream);            stream.Close();            requestStream.Close();            using (var response = request.GetResponse())            using (var responseStream = response.GetResponseStream())            using (var mstream = new MemoryStream())            {                responseStream.CopyTo(mstream);                return mstream.ToArray();            }        }        /// 
      
        /// 上传文件        /// 
        public class UploadFile        {            public UploadFile()            {                ContentType = "application/octet-stream";            }            public string Name { get; set; }            public string Filename { get; set; }            public string ContentType { get; set; }            public byte[] Data { get; set; }        }    }