这似乎可行，因为我在服务器上获得了一个大小合适的文件.

This seems to work, in that I get a file on the server of the right size.

1) 我如何流式传输它，而不是先将其加载到内存中?我将上传非常大的文件.

1) How do I stream it, rather than load it into memory first? I will be uploading very large files.

为了下载我有

using (WebClient client = new WebClient())
{
    string HtmlResult = String.Empty;
    FtpWebRequest request = (FtpWebRequest)WebRequest.Create(remoteFile);
    request.Method = WebRequestMethods.Ftp.DownloadFile;
    request.EnableSsl = false;
    request.Credentials = new NetworkCredential(MyLogin, MyPassword);
    using (FtpWebResponse response = (FtpWebResponse)request.GetResponse())
    using (Stream responseStream = response.GetResponseStream())
    using (StreamReader reader = new StreamReader(responseStream))
    using (FileStream writer = new FileStream(localFilename, FileMode.Create))
    {
        long length = response.ContentLength;
        int bufferSize = 2048;
        int readCount;
        byte[] buffer = new byte[2048];
        readCount = responseStream.Read(buffer, 0, bufferSize);
        while (readCount > 0)
        {
            writer.Write(buffer, 0, readCount);
            readCount = responseStream.Read(buffer, 0, bufferSize);
        }
    }
}

WebClient client = new WebClient();
client.Credentials = new NetworkCredential("username", "password");
client.UploadFile(
    "ftp://ftp.example.com/remote/path/file.zip", @"C:localpathfile.zip");

如果您需要更好的控制，WebClient 不提供(例如 TLS/SSL 加密，ascii/text 传输模式，传输恢复等)，使用 FtpWebRequest.简单的方法是使用 FileStream 复制到 FTP 流rel="nofollow noreferrer">Stream.CopyTo:

If you need a greater control, that WebClient does not offer (like TLS/SSL encryption, ascii/text transfer mode, transfer resuming, etc), use FtpWebRequest. Easy way is to just copy a FileStream to FTP stream using Stream.CopyTo:

FtpWebRequest request =
    (FtpWebRequest)WebRequest.Create("ftp://ftp.example.com/remote/path/file.zip");
request.Credentials = new NetworkCredential("username", "password");
request.Method = WebRequestMethods.Ftp.UploadFile;  

using (Stream fileStream = File.OpenRead(@"C:localpathfile.zip"))
using (Stream ftpStream = request.GetRequestStream())
{
    fileStream.CopyTo(ftpStream);
}

如果你需要监控一个上传进度，你必须自己分块复制内容:

If you need to monitor an upload progress, you have to copy the contents by chunks yourself:

FtpWebRequest request =
    (FtpWebRequest)WebRequest.Create("ftp://ftp.example.com/remote/path/file.zip");
request.Credentials = new NetworkCredential("username", "password");
request.Method = WebRequestMethods.Ftp.UploadFile;  

using (Stream fileStream = File.OpenRead(@"C:localpathfile.zip"))
using (Stream ftpStream = request.GetRequestStream())
{
    byte[] buffer = new byte[10240];
    int read;
    while ((read = fileStream.Read(buffer, 0, buffer.Length)) > 0)
    {
        ftpStream.Write(buffer, 0, read);
        Console.WriteLine("Uploaded {0} bytes", fileStream.Position);
    } 
}

GUI进度(WinForms ProgressBar)见:
如何使用 FtpWebRequest 显示上传进度条

For GUI progress (WinForms ProgressBar), see:
How can we show progress bar for upload with FtpWebRequest

如果要上传文件夹中的所有文件，请参阅
C#递归上传到FTP服务器.

If you want to upload all files from a folder, see
Recursive upload to FTP server in C#.

使用 .NET 框架从 FTP 服务器下载二进制文件最简单的方法是使用 WebClient.DownloadFile:

The most trivial way to download a binary file from an FTP server using .NET framework is using WebClient.DownloadFile:

WebClient client = new WebClient();
client.Credentials = new NetworkCredential("username", "password");
client.DownloadFile(
    "ftp://ftp.example.com/remote/path/file.zip", @"C:localpathfile.zip");