在 C#/.NET 中向/從 FTP 服務器上傳和下載文件

Question

我正在使用 .NET 4 C#。 我正在嘗試將 ZIP 文件上傳然后下載到（我的）服務器。

對於上傳我有

using (WebClient client = new WebClient())
{
    FtpWebRequest request = (FtpWebRequest)WebRequest.Create(MyUrl);
    request.Method = WebRequestMethods.Ftp.UploadFile;
    request.EnableSsl = false;
    request.Credentials = new NetworkCredential(MyLogin, MyPassword);
    byte[] fileContents = null;
    using (StreamReader sourceStream = new StreamReader(LocalFilePath))
    {
        fileContents = Encoding.UTF8.GetBytes(sourceStream.ReadToEnd());
    }
    request.ContentLength = fileContents.Length;
    using (Stream requestStream = request.GetRequestStream())
    {
        requestStream.Write(fileContents, 0, fileContents.Length);
    }
    FtpWebResponse response = null;
    response = (FtpWebResponse)request.GetResponse();
    response.Close();
}

這似乎有效，因為我在服務器上獲得了一個大小合適的文件。

1）如何流式傳輸，而不是先將其加載到內存中？ 我將上傳非常大的文件。

對於下載我有

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);
        }
    }
}

2) 一切似乎都在工作......除了當我嘗試解壓縮下載的 ZIP 文件時，我得到一個無效的 ZIP 文件。

Answer 1

上傳

使用 .NET 框架將二進制文件上傳到 FTP 服務器的最簡單方法是使用WebClient.UploadFile ：

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

如果您需要更好的控制，而WebClient不提供（如TLS/SSL 加密、ascii/文本傳輸模式、傳輸恢復等），請使用FtpWebRequest 。 簡單的方法是使用Stream.CopyTo將FileStream復制到 FTP 流：

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:\local\path\file.zip"))
using (Stream ftpStream = request.GetRequestStream())
{
    fileStream.CopyTo(ftpStream);
}

如果您需要監控上傳進度，您必須自己分塊復制內容：

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:\local\path\file.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);
    } 
}

對於 GUI 進度 (WinForms ProgressBar )，請參閱：
我們如何使用 FtpWebRequest 顯示上傳進度條

如果要上傳文件夾中的所有文件，請參閱
在 C# 中遞歸上傳到 FTP 服務器。

---

下載

使用 .NET 框架從 FTP 服務器下載二進制文件的最簡單方法是使用WebClient.DownloadFile ：

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

如果您需要更好的控制，而WebClient不提供（如TLS/SSL 加密、ascii/文本傳輸模式、恢復傳輸等），請使用FtpWebRequest 。 簡單的方法是使用Stream.CopyTo將 FTP 響應流復制到FileStream ：

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

using (Stream ftpStream = request.GetResponse().GetResponseStream())
using (Stream fileStream = File.Create(@"C:\local\path\file.zip"))
{
    ftpStream.CopyTo(fileStream);
}

如果您需要監控下載進度，您必須自己分塊復制內容：

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

using (Stream ftpStream = request.GetResponse().GetResponseStream())
using (Stream fileStream = File.Create(@"C:\local\path\file.zip"))
{
    byte[] buffer = new byte[10240];
    int read;
    while ((read = ftpStream.Read(buffer, 0, buffer.Length)) > 0)
    {
        fileStream.Write(buffer, 0, read);
        Console.WriteLine("Downloaded {0} bytes", fileStream.Position);
    }
}

對於 GUI 進度 (WinForms ProgressBar )，請參閱：
FtpWebRequest 使用 ProgressBar 進行 FTP 下載

如果要從遠程文件夾下載所有文件，請參閱
C# 通過 FTP 下載所有文件和子目錄。