http://blog.csdn.net/hellowjwang/article/details/19975635


public class HttpPost
    {


        /// <summary>
        /// 以Post 形式提交数据到 uri
        /// </summary>
        /// <param name="uri"></param>
        /// <param name="files"></param>
        /// <param name="values"></param>
        /// <returns></returns>
        public static byte[] Post(Uri uri, IEnumerable<UploadFile> 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();
            }
        }










        /// <summary>
        /// 上传文件
        /// </summary>
        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; }
        }




    }