Post 的資料好像會變大, 要改 Web.config

<system.web>

    <httpRuntime requestValidationMode="2.0" maxRequestLength="1024000"/>

</system.web>

程式碼如下:

public string UploadFilesToRemoteUrl(string url, string[] files, NameValueCollection formFields = null)

    {

        string boundary = "----------------------------" + DateTime.Now.Ticks.ToString("x");



        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);

        request.ContentType = "multipart/form-data; boundary=" +

                                boundary;

        request.Method = "POST";

        request.KeepAlive = true;



        Stream memStream = new System.IO.MemoryStream();



        var boundarybytes = System.Text.Encoding.ASCII.GetBytes("\r\n--" +

                                                                boundary + "\r\n");

        var endBoundaryBytes = System.Text.Encoding.ASCII.GetBytes("\r\n--" +

                                                                    boundary + "--");





        string formdataTemplate = "\r\n--" + boundary +

                                    "\r\nContent-Disposition: form-data; name=\"{0}\";\r\n\r\n{1}";



        if (formFields != null)

        {

            foreach (string key in formFields.Keys)

            {

                string formitem = string.Format(formdataTemplate, key, formFields[key]);

                byte[] formitembytes = System.Text.Encoding.UTF8.GetBytes(formitem);

                memStream.Write(formitembytes, 0, formitembytes.Length);

            }

        }



        string headerTemplate =

            "Content-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"\r\n" +

            "Content-Type: application/octet-stream\r\n\r\n";



        for (int i = 0; i < files.Length; i++)

        {

            memStream.Write(boundarybytes, 0, boundarybytes.Length);

            var header = string.Format(headerTemplate, "uplTheFile", files[i]);

            var headerbytes = System.Text.Encoding.UTF8.GetBytes(header);



            memStream.Write(headerbytes, 0, headerbytes.Length);



            using (var fileStream = new FileStream(files[i], FileMode.Open, FileAccess.Read))

            {

                var buffer = new byte[1024];

                var bytesRead = 0;

                while ((bytesRead = fileStream.Read(buffer, 0, buffer.Length)) != 0)

                {

                    Response.Write("bytesRead: " + bytesRead.ToString() + "<br>");

                    memStream.Write(buffer, 0, bytesRead);

                }

            }

        }



        memStream.Write(endBoundaryBytes, 0, endBoundaryBytes.Length);

        request.ContentLength = memStream.Length;



        using (Stream requestStream = request.GetRequestStream())

        {

            memStream.Position = 0;

            byte[] tempBuffer = new byte[memStream.Length];

            memStream.Read(tempBuffer, 0, tempBuffer.Length);

            memStream.Close();

            requestStream.Write(tempBuffer, 0, tempBuffer.Length);

        }



        try

        {

            using (var response = request.GetResponse())

            {

                Stream stream2 = response.GetResponseStream();

                StreamReader reader2 = new StreamReader(stream2);

                return reader2.ReadToEnd();

            }

        }

        catch (Exception ex)

        {

            return (ex.ToString());

            throw;

        }

    }

客戶要求
1. 檔案只能放在 Firewall 內的後台用 Web server (Server A).
2. 使用者只能存取 DMZ 的 Web server (Server B).
3. Server B 只能用 HTTP 通過 Firewall 向 Server A 要資料.(i.e.  Server B 不能掛戴 Server A 的目錄成為虛擬目錄)

所以在 Server B 上面建立了一支程式用 HTTP 的方式讀取 Server A 的檔案再寫出去.

例如, http://ServerB/Upload/test.pdf 會讀取 http://ServerA/Upload/test.pdf 再送到 Client 端

namespace WWW.Controllers

{

    public class UploadController : Controller

    {

        // GET: Upload

        public void Index(string Filename)

        {

            //Create a stream for the file

            Stream stream = null;



            //This controls how many bytes to read at a time and send to the client

            int bytesToRead = 10000;



            // Buffer to read bytes in chunk size specified above

            byte[] buffer = new Byte[bytesToRead];



            string url = "http://admin-dev.nanya.bike.idv.tw/newnanyaback/Upload/" + Filename;



            // The number of bytes read

            try

            {

                //Create a WebRequest to get the file

                HttpWebRequest fileReq = (HttpWebRequest)HttpWebRequest.Create(url);



                //Create a response for this request

                HttpWebResponse fileResp = (HttpWebResponse)fileReq.GetResponse();



                if (fileReq.ContentLength > 0)

                    fileResp.ContentLength = fileReq.ContentLength;



                //Get the Stream returned from the response

                stream = fileResp.GetResponseStream();



                // prepare the response to the client. resp is the client Response

                var resp = HttpContext.Response;



                if (Filename.ToLower().EndsWith(".png") ||

                    Filename.ToLower().EndsWith(".jpg") ||

                    Filename.ToLower().EndsWith(".jpeg") ||

                    Filename.ToLower().EndsWith(".gif")

                    )

                {

                    resp.ContentType = "image";

                }

                else

                {

                    //Indicate the type of data being sent

                    resp.ContentType = "application/octet-stream";



                    //Name the file

                    resp.AddHeader("Content-Disposition", "attachment; filename=\"" + HttpUtility.UrlEncode(Filename, Encoding.UTF8) + "\"");

                }



                resp.AddHeader("Content-Length", fileResp.ContentLength.ToString());



                int length;

                do

                {

                    // Verify that the client is connected.

                    if (resp.IsClientConnected)

                    {

                        // Read data into the buffer.

                        length = stream.Read(buffer, 0, bytesToRead);



                        // and write it out to the response's output stream

                        resp.OutputStream.Write(buffer, 0, length);



                        // Flush the data

                        resp.Flush();



                        //Clear the buffer

                        buffer = new Byte[bytesToRead];

                    }

                    else

                    {

                        // cancel the download if client has disconnected

                        length = -1;

                    }

                } while (length > 0); //Repeat until no data is read

            }

            finally

            {

                if (stream != null)

                {

                    //Close the input stream

                    stream.Close();

                }

            }

        }

    }

}

但不是這樣就好了, 在 RouteConfig.cs 中要加上:
            routes.MapRoute(
                name: "Upload",
                url: "Upload/{filename}",
                defaults: new { controller = "Upload", action = "Index", filename = UrlParameter.Optional }
            );

此外在 Web.Config 中也要加上:

  <system.webServer>
    <handlers>
      <add name="UrlRoutingHandler_Upload"
           type="System.Web.Routing.UrlRoutingHandler, 
               System.Web, Version=4.0.0.0, 
               Culture=neutral, 
               PublicKeyToken=b03f5f7f11d50a3a"
           path="/Upload/*"
           verb="GET"/>
    </handlers>
  </system.webServer>

參考:
http://stackoverflow.com/questions/5596747/download-stream-file-from-url-asp-net

http://blog.darkthread.net/post-2014-12-05-mvc-routing-for-url-with-filename.aspx