在 WinForms 应用中使用 FtpWebRequest 进行文件操作和数据显示

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引言

在企业级应用或桌面程序中，经常需要从远程服务器获取数据，并在用户界面上展示这些数据。本文将通过一个实际案例，演示如何在 Windows Forms 应用程序中使用 FtpWebRequest 来下载文件，并使用 DataGridView 控件显示解析后的日志数据。

使用 FtpWebRequest 进行 FTP 文件下载

FTP（文件传输协议）是用于文件上传和下载的常用协议。在 .NET Framework 中，FtpWebRequest 类提供了处理 FTP 通信的功能。以下是一个使用 FtpWebRequest 下载文件的示例：

class FtpDownloader
{
    private string ftpServerIP;
    private string ftpUserID;
    private string ftpPassword;

    public FtpDownloader(string ftpServerIP, string ftpUserID, string ftpPassword)
    {
        this.ftpServerIP = ftpServerIP;
        this.ftpUserID = ftpUserID;
        this.ftpPassword = ftpPassword;
    }

    public bool DownloadFile(string remoteFilePath, string localFilePath, out string error)
    {
        string ftpUrl = $"ftp://{ftpServerIP}/{remoteFilePath}";
        FtpWebRequest request = (FtpWebRequest)WebRequest.Create(ftpUrl);
        request.Method = WebRequestMethods.Ftp.DownloadFile;
        request.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
        request.UsePassive = false;
        request.UseBinary = true;
        request.KeepAlive = false;
        request.Timeout = 3000;
        request.ReadWriteTimeout = 3000;

        try
        {
            using (FtpWebResponse response = (FtpWebResponse)request.GetResponse())
            using (Stream responseStream = response.GetResponseStream())
            using (FileStream fileStream = new FileStream(localFilePath, FileMode.Create))
            {
                responseStream.CopyTo(fileStream);
            }

            Console.WriteLine($"Downloaded {remoteFilePath} to {localFilePath}");
            error = "success";
            return true;
        }
        catch (Exception ex)
        {
            Console.WriteLine("Error: " + ex.Message);
            error = ex.Message;
            return false;
        }
    }
}

显示和解析日志数据

一旦文件被下载，下一步就是解析这些日志数据并展示在 DataGridView 控件中。以下是解析日志数据并加载到 DataTable，然后绑定到 DataGridView 的过程：

public partial class MainForm : Form
{
    private DataTable logDataTable;
    private DataGridView dataGridViewLogs;

    public MainForm()
    {
        InitializeComponent();
        InitializeLogDataTable();
    }

    private void InitializeLogDataTable()
    {
        logDataTable = new DataTable();
        logDataTable.Columns.Add("EntryNumber", typeof(int));
        logDataTable.Columns.Add("ProcessID", typeof(int));
        logDataTable.Columns.Add("DateTime", typeof(DateTime));
        logDataTable.Columns.Add("Task", typeof(string));
        logDataTable.Columns.Add("Level", typeof(string));
        logDataTable.Columns.Add("Message", typeof(string));

        dataGridViewLogs.DataSource = logDataTable;
    }

    private void LoadLogs()
    {
        string logFilePath = "./myLog";
        logDataTable.Rows.Clear();

        foreach (var line in File.ReadAllLines(logFilePath))
        {
            var logEntry = ParseLogLine(line);
            if (logEntry != null)
            {
                logDataTable.Rows.Add(logEntry);
            }
        }
    }

    private object[] ParseLogLine(string line)
    {
        var logPattern = new Regex(@"(\d+) (\d+) \[(.*?)\] \[(.*?)\] \[(.*?)\]: (.*)");
        var match = logPattern.Match(line);

        if (match.Success)
        {
            return new object[]
            {
                int.Parse(match.Groups[1].Value),
                int.Parse(match.Groups[2].Value),
                DateTime.Parse(match.Groups[3].Value),
                match.Groups[4].Value,
                match.Groups[5].Value,
                match.Groups[6].Value
            };
        }
        return null;
    }
}