c#-4.0 - https 経由でファイルをアップロードする

Question

この種のファイル アップロード用の C# コード スニペットを教えてください。

POST <BASE-URL>/documents
Content-Type: multipart/form-data; boundary=<BOUNDARY>
Transfer-Encoding: chunked
--<BOUNDARY>
Content-Disposition: form-data; name=“metadata”
Content-Type: application/json
{
“metadata” : {
“document” : {
“filename” : <filename>,
“size” : <filesize>,
“title” : <title>,
“author” : <author>
}
}
}
--<BOUNDARY>
Content-Disposition: form-data; name=“document”; filename=“&lt;filename>”
Content-Type: <mime-type>
<File contents>
--<BOUNDARY>--

現在、以下に示す方法を使用しており、ステータス 400:Bad Request: を取得しています。

 public static void HttpUploadFile(string url, string file, string paramName, string contentType, NameValueCollection nvc,string accessToken)
    {

        string boundary = "---------------------------" + DateTime.Now.Ticks.ToString("x");
        byte[] boundarybytes = System.Text.Encoding.ASCII.GetBytes("\r\n--" + boundary + "\r\n");

        HttpWebRequest wr = (HttpWebRequest)WebRequest.Create(url);
        wr.ContentType = "multipart/form-data; boundary=" + boundary;
        wr.Method = "POST";
        wr.KeepAlive = false;
        wr.SendChunked = true;
        wr.Headers.Add("Authorization", "Bearer " + accessToken);
        wr.Credentials = System.Net.CredentialCache.DefaultCredentials;

        Stream rs = wr.GetRequestStream();

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

        foreach (string key in nvc.Keys)
        {
            rs.Write(boundarybytes, 0, boundarybytes.Length);
            string formitem = string.Format(formdataTemplate, key, nvc[key]);
            byte[] formitembytes = System.Text.Encoding.UTF8.GetBytes(formitem);
            rs.Write(formitembytes, 0, formitembytes.Length);
        }
        rs.Write(boundarybytes, 0, boundarybytes.Length);

        string headerTemplate = "Content-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"\r\nContent-Type: {2}\r\n\r\n";
        string header = string.Format(headerTemplate, paramName, file, contentType);
        byte[] headerbytes = System.Text.Encoding.UTF8.GetBytes(header);
        rs.Write(headerbytes, 0, headerbytes.Length);

        FileStream fileStream = new FileStream(file, FileMode.Open, FileAccess.Read);
        byte[] buffer = new byte[256000];
        int bytesRead = 0;
        while ((bytesRead = fileStream.Read(buffer, 0, buffer.Length)) != 0)
        {
            rs.Write(buffer, 0, bytesRead);
        }
        fileStream.Close();

        byte[] trailer = System.Text.Encoding.ASCII.GetBytes("\r\n--" + boundary + "--\r\n");
        rs.Write(trailer, 0, trailer.Length);
        rs.Close();

        WebResponse wresp = null;
        try
        {
            wresp = wr.GetResponse();
            Stream stream2 = wresp.GetResponseStream();
            StreamReader reader2 = new StreamReader(stream2);
            //log.Debug(string.Format("File uploaded, server response is: {0}", reader2.ReadToEnd()));
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.ToString());
            if (wresp != null)
            {
                wresp.Close();
                wresp = null;
            }
        }
        finally
        {
            wr = null;
        }
    }

問題を引き起こすのは、投稿ヘッダーのフォームデータのjson文字列部分だと思います...ここではnamevaluecollectionを使用しています...

ありがとう！