【问题标题】:application/form-data in C# application?C# 应用程序中的应用程序/表单数据?
【发布时间】:2017-05-01 20:30:47
【问题描述】:

我使用下面的代码使用 C# 控制台应用程序将文件上传到 url。它不上传文件也不返回错误。

string[] files = new string []{ "C:/test.csv" };


public static 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)
                {
                    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);
        }

        using (var response = request.GetResponse())
        {
            Stream stream2 = response.GetResponseStream();
            StreamReader reader2 = new StreamReader(stream2);
            return reader2.ReadToEnd();
        }
    }

Upload files with HTTPWebrequest (multipart/form-data)

我已经检查了这段代码,它没有在我给出的 url 中上传文件,也没有错误返回。

【问题讨论】:

  • 不应该是multipart/form-data吗?
  • 我需要在“multipart/form-data”中传递文件

标签: c# http httpwebrequest httpwebresponse


【解决方案1】:

这里已经回答了这个问题: Upload files with HTTPWebrequest (multipart/form-data)

另外,请注意,在您的代码中,您实际上发送的是字符串"C:/test.csv",而不是文件的内容!您将需要打开一个FileStream (https://msdn.microsoft.com/en-us/library/system.io.filestream.aspx) 以流出它的内容。 (这也包含在上面链接的答案中)

【讨论】:

  • @Stepan 我已经在链接中尝试过你的代码,它不会上传文件也不会返回错误
  • 假设您使用的是现代版本的 .net,请尝试以下答案:stackoverflow.com/a/16925159/3111401
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