我最近不得不处理这个问题——另一种方法是使用WebClient是可继承的这一事实，并从那里改变底层的WebRequest:

http://msdn.microsoft.com/en-us/library/system.net.webclient.getwebrequest (VS.80) . aspx

我更喜欢c#，但如果你坚持使用VB，结果将是这样的:

Public Class BigWebClient
    Inherits WebClient
    Protected Overrides Function GetWebRequest(ByVal address As System.Uri) As System.Net.WebRequest
        Dim x As WebRequest = MyBase.GetWebRequest(address)
        x.Timeout = 60 * 60 * 1000
        Return x
    End Function
End Class

'Use BigWebClient here instead of WebClient

对于我来说，下面的作品(主要是受到以下所有回答的启发)，我从Elad的回答开始，修改/简化事情以符合我的需要(删除不是文件形式输入，只有一个文件，……)

希望它能帮助到一些人:)

(PS:我知道异常处理没有实现，并且假设它是在一个类中编写的，所以我可能需要一些集成工作…)

private void uploadFile()
    {
        Random rand = new Random();
        string boundary = "----boundary" + rand.Next().ToString();
        Stream data_stream;
        byte[] header = System.Text.Encoding.ASCII.GetBytes("\r\n--" + boundary + "\r\nContent-Disposition: form-data; name=\"file_path\"; filename=\"" + System.IO.Path.GetFileName(this.file) + "\"\r\nContent-Type: application/octet-stream\r\n\r\n");
        byte[] trailer = System.Text.Encoding.ASCII.GetBytes("\r\n--" + boundary + "--\r\n");

        // Do the request
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(MBF_URL);
        request.UserAgent = "My Toolbox";
        request.Method = "POST";
        request.KeepAlive = true;
        request.ContentType = "multipart/form-data; boundary=" + boundary;
        data_stream = request.GetRequestStream();
        data_stream.Write(header, 0, header.Length);
        byte[] file_bytes = System.IO.File.ReadAllBytes(this.file);
        data_stream.Write(file_bytes, 0, file_bytes.Length);
        data_stream.Write(trailer, 0, trailer.Length);
        data_stream.Close();

        // Read the response
        WebResponse response = request.GetResponse();
        data_stream = response.GetResponseStream();
        StreamReader reader = new StreamReader(data_stream);
        this.url = reader.ReadToEnd();

        if (this.url == "") { this.url = "No response :("; }

        reader.Close();
        data_stream.Close();
        response.Close();
    }

类似这样的代码很接近:(未测试的代码)

byte[] data; // data goes here.

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.Credentials = userNetworkCredentials;
request.Method = "PUT";
request.ContentType = "application/octet-stream";
request.ContentLength = data.Length;
Stream stream = request.GetRequestStream();
stream.Write(data,0,data.Length);
stream.Close();
response = (HttpWebResponse)request.GetResponse();
StreamReader reader = new StreamReader(response.GetResponseStream());
temp = reader.ReadToEnd();
reader.Close();

采取以上和修改它接受一些头值，和多个文件

    NameValueCollection headers = new NameValueCollection();
        headers.Add("Cookie", "name=value;");
        headers.Add("Referer", "http://google.com");
    NameValueCollection nvc = new NameValueCollection();
        nvc.Add("name", "value");

    HttpUploadFile(url, new string[] { "c:\\file1.txt", "c:\\file2.jpg" }, new string[] { "file", "image" }, new string[] { "application/octet-stream", "image/jpeg" }, nvc, headers);

public static void HttpUploadFile(string url, string[] file, string[] paramName, string[] contentType, NameValueCollection nvc, NameValueCollection headerItems)
{
    //log.Debug(string.Format("Uploading {0} to {1}", file, url));
    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);

    foreach (string key in headerItems.Keys)
    {
        if (key == "Referer")
        {
            wr.Referer = headerItems[key];
        }
        else
        {
            wr.Headers.Add(key, headerItems[key]);
        }
    }

    wr.ContentType = "multipart/form-data; boundary=" + boundary;
    wr.Method = "POST";
    wr.KeepAlive = true;
    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 = "";

    for(int i =0; i<file.Count();i++)
    {
        header = string.Format(headerTemplate, paramName[i], System.IO.Path.GetFileName(file[i]), contentType[i]);
        byte[] headerbytes = System.Text.Encoding.UTF8.GetBytes(header);
        rs.Write(headerbytes, 0, headerbytes.Length);

        FileStream fileStream = new FileStream(file[i], FileMode.Open, FileAccess.Read);
        byte[] buffer = new byte[4096];
        int bytesRead = 0;
        while ((bytesRead = fileStream.Read(buffer, 0, buffer.Length)) != 0)
        {
            rs.Write(buffer, 0, bytesRead);
        }
        fileStream.Close();
        rs.Write(boundarybytes, 0, boundarybytes.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)
    {
        //log.Error("Error uploading file", ex);
            wresp.Close();
            wresp = null;
    }
    finally
    {
        wr = null;
    }
}

我知道这可能有点晚了，但我一直在寻找同样的解决方案。我从一位微软代表那里找到了以下回复

private void UploadFilesToRemoteUrl(string url, string[] files, string logpath, NameValueCollection nvc)
{

    long length = 0;
    string boundary = "----------------------------" +
    DateTime.Now.Ticks.ToString("x");


    HttpWebRequest httpWebRequest2 = (HttpWebRequest)WebRequest.Create(url);
    httpWebRequest2.ContentType = "multipart/form-data; boundary=" +
    boundary;
    httpWebRequest2.Method = "POST";
    httpWebRequest2.KeepAlive = true;
    httpWebRequest2.Credentials = System.Net.CredentialCache.DefaultCredentials;



    Stream memStream = new System.IO.MemoryStream();
    byte[] boundarybytes = System.Text.Encoding.ASCII.GetBytes("\r\n--" + boundary + "\r\n");


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

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


    memStream.Write(boundarybytes,0,boundarybytes.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++)
    {

        string header = string.Format(headerTemplate,"file"+i,files[i]);
        byte[] headerbytes = System.Text.Encoding.UTF8.GetBytes(header);
        memStream.Write(headerbytes,0,headerbytes.Length);


        FileStream fileStream = new FileStream(files[i], FileMode.Open,
        FileAccess.Read);
        byte[] buffer = new byte[1024];

        int bytesRead = 0;

        while ( (bytesRead = fileStream.Read(buffer, 0, buffer.Length)) != 0 )
        {
            memStream.Write(buffer, 0, bytesRead);
        }


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


        fileStream.Close();
    }

    httpWebRequest2.ContentLength = memStream.Length;
    Stream requestStream = httpWebRequest2.GetRequestStream();

    memStream.Position = 0;
    byte[] tempBuffer = new byte[memStream.Length];
    memStream.Read(tempBuffer,0,tempBuffer.Length);
    memStream.Close();
    requestStream.Write(tempBuffer,0,tempBuffer.Length );
    requestStream.Close();


    WebResponse webResponse2 = httpWebRequest2.GetResponse();

    Stream stream2 = webResponse2.GetResponseStream();
    StreamReader reader2 = new StreamReader(stream2);

    webResponse2.Close();
    httpWebRequest2 = null;
    webResponse2 = null;

}

不确定这是否张贴之前，但我得到了这个工作与WebClient。我读了WebClient的文档。他们提出的一个关键点是

如果BaseAddress属性不是空字符串("")和address 不包含绝对URI，地址必须是相对URI那 与BaseAddress结合形成所请求的URI的绝对URI 数据。如果QueryString属性不是空字符串，那么它就是空字符串 附于地址。

我所做的就是wc。querystring。添加(“源”，generatedImage)来添加不同的查询参数，以某种方式将属性名称与我上传的图像匹配。希望能有所帮助

    public void postImageToFacebook(string generatedImage, string fbGraphUrl)
    {
        WebClient wc = new WebClient();
        byte[] bytes = System.IO.File.ReadAllBytes(generatedImage);

        wc.QueryString.Add("source", generatedImage);
        wc.QueryString.Add("message", "helloworld");

        wc.UploadFile(fbGraphUrl, generatedImage);

        wc.Dispose();

    }