【FTP】Csharp 版

文前言

意外發現原來 FTP 跟 SFTP 寫法是不同的...
來擴充版面吧！

FTP: 使用 FtpWebRequest
SFTP: 使用 sshnet/SSH.NET: SSH.NET is a Secure Shell (SSH) library for .NET, optimized for parallelism.

主文

FTP

基礎

取得遠端某資料夾內所有檔案清單

Follow Fang!: C#.Net 透過FtpWebRequest取得FTP檔案清單

自遠端下載檔案

［C#］從ftp server下載檔案＠[C#] 資料結構與影像處理｜PChome Online 個人新聞台

循環從本機上傳資料夾內所有檔案到遠端

/// <summary>
/// 複製本機資料夾至遠端 (不含子資料夾)
/// </summary>
/// <param name="srcDir"></param>
/// <param name="ftpDir"></param>
/// <param name="usrname"></param>
/// <param name="pwd"></param>
private void CopyLocal2Ftp(string srcDir, string ftpDir, string usrname, string pwd)
{
    string[] files = Directory.GetFiles(srcDir, "*", SearchOption.AllDirectories);
    foreach (string file in files)
    {
        UploadFileToFTP(file, ftpDir, usrname, pwd);
    }
}

/// <summary>
/// 單檔上傳至 FTP 指定資料夾
/// </summary>
/// <param name="localFilePath"></param>
/// <param name="ftpFilePath">FTP 指定資料夾</param>
/// <param name="username"></param>
/// <param name="password"></param>
private void UploadFileToFTP(string localFilePath, string ftpFilePath, string username, string password)
{
    string uploadfile = ftpFilePath + Path.GetFileName(localFilePath);
    try
    {
        FtpWebRequest request = (FtpWebRequest)WebRequest.Create(uploadfile);
        request.Method = WebRequestMethods.Ftp.UploadFile;
        request.Credentials = new NetworkCredential(username, password);
        request.UsePassive = true;
        request.UseBinary = true;
        request.KeepAlive = false;

        byte[] fileContents = File.ReadAllBytes(localFilePath);
        request.ContentLength = fileContents.Length;

        using (Stream requestStream = request.GetRequestStream())
        {
            requestStream.Write(fileContents, 0, fileContents.Length);
        }

        using (FtpWebResponse response = (FtpWebResponse)request.GetResponse())
        {
            logger.Info($"檔案 {uploadfile} 上傳至 FTP 成功。({response.StatusDescription})");
        }
    }
    catch (Exception ex)
    {
        logger.Error($"檔案 {uploadfile} 上傳至 FTP 失敗！錯誤訊息：{ex}");
    }
}

進階

檢查資料夾是否存在

c# - How to Determine if FTP Directory Exists - Stack Overflow

於遠端建立新資料夾

.net - How do I create a directory on FTP server using C#? - Stack Overflow

建立多層子資料夾

/// <summary>
/// 建立多層子資料夾
/// </summary>
/// <param name="ftpDirectory">以 "/" 分割，不用帶最後一條 "/"</param>
/// <param name="username"></param>
/// <param name="password"></param>
private void CreateFtpDirectories(string ftp, string ftpDirectory, string username, string password)
{
    try
    {
        string[] folders = ftpDirectory.Split('/');
        string currentPath = ftp;

        foreach (string folder in folders)
        {
            currentPath = $"{currentPath}/{folder}/";

            if (!sharedFunction.DirectoryExists(currentPath, username, password))
            {
                FtpWebRequest request = (FtpWebRequest)WebRequest.Create(currentPath);
                request.Method = WebRequestMethods.Ftp.MakeDirectory;
                request.Credentials = new NetworkCredential(username, password);
                request.UsePassive = true;
                request.UseBinary = true;
                request.KeepAlive = false;

                using (FtpWebResponse response = (FtpWebResponse)request.GetResponse()) { }
            }
        }
    }
    catch (WebException ex)
    {
        FtpWebResponse response = (FtpWebResponse)ex.Response;
        if (response != null && response.StatusCode == FtpStatusCode.ActionNotTakenFileUnavailable)
        {
            // 目錄已存在，忽略錯誤
        }
        else
        {
            logger.Error($"建立 {ftpDirectory} 資料夾失敗！WebException 錯誤訊息：{ex}");
        }
    }
    catch (Exception ex)
    {
        logger.Error($"建立 {ftpDirectory} 資料夾失敗！其他錯誤訊息：{ex}");
    }
}

本機上傳整個資料夾到遠端

recursion - C# Upload whole directory using FTP - Stack Overflow

資料夾檔名更新

參考： 1. c# - Rename directory on FTP server using FtpWebRequest - Stack Overflow 2. c# - How to rename a file after upload - Stack Overflow

string ftpDirectory = $"{ftpServer}/old";  

FtpWebRequest request = (FtpWebRequest)WebRequest.Create(ftpDirectory);  
request.Method = WebRequestMethods.Ftp.Rename;  
request.Credentials = new NetworkCredential(usrname, pwd);  
request.RenameTo = $"new";  

try  
{  
    // 發送請求並取得回應  
    using (FtpWebResponse response = (FtpWebResponse)request.GetResponse())  
    {  
        logger.Info(
            $"資料夾名稱已成功更改為：new；"+
            $"伺服器回應：{response.StatusDescription}"
        );
    }  
}  
catch (Exception ex)  
{  
    logger.Error($"檔案資料夾名稱改名失敗！錯誤訊息：{ex.ToString()}");  
}

下載檔案後附檔寄信

ref: asp.net - Attach file existing on FTP server to mail in C# .NET - Stack Overflow

SFTP

前置

ChatGPT 推薦安裝套件：
sshnet/SSH.NET: SSH.NET is a Secure Shell (SSH) library for .NET, optimized for parallelism.

使用

目前只用來撈指定資料夾的最新更新時間。
然而 FTP & SFTP 似乎都不太好撈資料夾的時間，所以只能 loop 資料夾內所有檔案。
belike 費波納契數列 那樣的 recursive。

(以下程式碼來自 ChatGPT、me 調整修修)

static void Main()
{
    string host = "192.168.X.X";
    string username = "yourUsername";
    string password = "yourPassword";
    string rootPath = "/your/target/folder";

    using (var sftp = new SftpClient(host, 22, username, password))
    {
        sftp.Connect();
        DateTime latest = GetLatestModifiedTimeRecursive(sftp, rootPath);
        sftp.Disconnect();

        Console.WriteLine("Latest modified time: " + latest);
    }
}

static DateTime GetLatestModifiedTimeRecursive(SftpClient sftp, string path)
{
    DateTime latestTime = DateTime.MinValue;

    IEnumerable<ISftpFile> entries = sftp.ListDirectory(path);

    foreach (ISftpFile entry in entries)
    {
        // 略過目前資料夾(.) 與上一層資料夾(..) 的項目
        if (entry.Name == "." || entry.Name == "..")
            continue;

        if (entry.IsDirectory)
        {
            // recursive!!
            DateTime subTime 
                = GetLatestModifiedTimeRecursive(sftp, entry.FullName);

            if (subTime > latestTime)
                latestTime = subTime;
        }
        else if (entry.IsRegularFile)
        {
            DateTime fileTime = entry.LastWriteTime;
            if (fileTime > latestTime)
                latestTime = fileTime;
        }
    }

    return latestTime;
}

以上程式碼不含 try-catch，有需要的請記得加上。

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