Csharp 使用C#HttpClient以多部分形式数据发送带有非ASCII文件名的文件的问题

try 使用HttpWebRequest而不是HttpClient上载文件

示例代码:

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

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

        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
        request.ContentType = "multipart/form-data; boundary=" + boundary;
        request.Method = "POST";
        request.KeepAlive = true;
        request.Credentials = System.Net.CredentialCache.DefaultCredentials;

        Stream requestStream = request.GetRequestStream();

        string formdataTemplate = "Content-Disposition: form-data; name=\"{0}\"\r\n\r\n{1}";
        foreach (string key in nvc.Keys)
        {
            requestStream.Write(boundarybytes, 0, boundarybytes.Length);
            string formitem = string.Format(formdataTemplate, key, nvc[key]);
            byte[] formitembytes = System.Text.Encoding.UTF8.GetBytes(formitem);
            requestStream.Write(formitembytes, 0, formitembytes.Length);
        }
        requestStream.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, "aaa.pdf", contentType);
        byte[] headerbytes = System.Text.Encoding.UTF8.GetBytes(header);
        requestStream.Write(headerbytes, 0, headerbytes.Length);

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

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

        WebResponse wresp = null;
        try
        {
            wresp = request.GetResponse();
            Stream stream2 = wresp.GetResponseStream();
            StreamReader reader2 = new StreamReader(stream2);
            string result = reader2.ReadToEnd();
        }

        catch (WebException ex)
        {
            using (var stream = ex?.Response?.GetResponseStream())
                if (stream != null)
                    using (var reader = new StreamReader(stream))
                    {
                        string result = reader.ReadToEnd();
                        Console.WriteLine(reader.ReadToEnd());
                    }

        }
        catch (Exception ex)
        {
            if (wresp != null)
            {
                wresp.Close();
                wresp = null;
            }

        }
        finally
        {
            request = null;
        }
    }