C# winform上传文件

以下是C# WinForm上传文件的示例代码：

private void btnUpload_Click(object sender, EventArgs e)
{
    OpenFileDialog openFileDialog = new OpenFileDialog();
    if (openFileDialog.ShowDialog() == DialogResult.OK)
    {
        string filePath = openFileDialog.FileName;
        string url = "http://localhost/UploadFileWeb/WebForm1.aspx";
        string paramName = "file";
        HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
        request.Method = "POST";
        string boundary = "---------------------------" + DateTime.Now.Ticks.ToString("x");
        byte[] boundaryBytes = Encoding.ASCII.GetBytes("\r\n--" + boundary + "\r\n");
        request.ContentType = "multipart/form-data; boundary=" + boundary;
        using (Stream requestStream = request.GetRequestStream())
        {
            requestStream.Write(boundaryBytes, 0, boundaryBytes.Length);
            string headerTemplate = "Content-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"\r\nContent-Type: application/octet-stream\r\n\r\n";
            string header = string.Format(headerTemplate, paramName, Path.GetFileName(filePath));
            byte[] headerBytes = Encoding.UTF8.GetBytes(header);
            requestStream.Write(headerBytes, 0, headerBytes.Length);
            using (FileStream fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read))
            {
                byte[] buffer = new byte[4096];
                int bytesRead = 0;
                while ((bytesRead = fileStream.Read(buffer, 0, buffer.Length)) != 0)
                {
                    requestStream.Write(buffer, 0, bytesRead);
                }
            }
            byte[] trailerBytes = Encoding.ASCII.GetBytes("\r\n--" + boundary + "--\r\n");
            requestStream.Write(trailerBytes, 0, trailerBytes.Length);
        }
        using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
        {
            using (StreamReader reader = new StreamReader(response.GetResponseStream()))
            {
                string responseText = reader.ReadToEnd();
                MessageBox.Show(responseText);
            }
        }
    }
}

该示例代码使用HttpWebRequest类向指定的URL上传文件。在上传文件之前，需要设置请求的Method为POST，ContentType为multipart/form-data，并设置请求头部的边界（boundary）。然后，将文件内容写入请求流中，最后发送请求并获取响应。在获取响应后，可以从响应流中读取服务器返回的内容。