C#FTP自动下载文件

在C#中，如果你想要编写一个FTP自动下载文件的脚本，可以使用定时任务或者循环来定期访问FTP服务器。下面是一个基本的例子，展示了如何使用Task异步下载，并且设置一个间隔时间重复下载：

using System;
using System.IO;
using System.Net;
using System.Threading.Tasks;
using System.Timers;

class FTPAutoDownloader {
    private readonly string _ftpServerUrl;
    private readonly string _username;
    private readonly string _password;
    private readonly string _remoteDirectory;
    private readonly string _localPath;
    private Timer _downloadTimer;

    public FTPAutoDownloader(string ftpServerUrl, string username, string password, string remoteDirectory, string localPath) {
        _ftpServerUrl = ftpServerUrl;
        _username = username;
        _password = password;
        _remoteDirectory = remoteDirectory;
        _localPath = localPath;
        
        _downloadTimer = new Timer(60 * 1000); // 每分钟执行一次下载任务
        _downloadTimer.Elapsed += OnDownloadTimerElapsed;
        _downloadTimer.Enabled = true;
    }

    private void OnDownloadTimerElapsed(object sender, ElapsedEventArgs e) {
        DownloadFilesFromFTP();
    }

    private async Task DownloadFilesFromFTP() {
        try {
            var directoryInfo = new DirectoryInfo(_ftpServerUrl + _remoteDirectory);
            foreach (var fileInfo in directoryInfo.GetFiles()) {
                var fileName = fileInfo.Name;
                var filePath = Path.Combine(_localPath, fileName);

                await DownloadFileAsync(fileInfo.FullName, filePath);
            }
        } catch (Exception ex) {
            Console.WriteLine($"FTP下载失败: {ex.Message}");
        }
    }

    private async Task DownloadFileAsync(string remoteFilePath, string localFilePath) {
        using (FtpWebRequest request = (FtpWebRequest)WebRequest.Create(remoteFilePath)) {
            request.Method = WebRequestMethods.Ftp.DownloadFile;
            request.Credentials = new NetworkCredential(_username, _password);

            using (var response = (FtpWebResponse)await request.GetResponseAsync()) {
                await response.Stream.CopyToAsync(File.OpenWrite(localFilePath));
            }
        }
    }
}

// 启动下载器
FAutoDownloader downloader = new FTPAutoDownloader("ftp://example.com", "your_username", "your_password", "/path/to/files/", "C:\\YourFolder\\Downloads");

在这个例子中，每隔一分钟（通过Timer控制），它会尝试从指定的FTP目录下载所有文件。