在 C# while 循环中使用 WinSCP .NET 程序集检查 SFTP 连接

Question

我想在控制台应用程序中显示实时连接状态。问题是我陷入了循环，并且不知道如何在循环时正确检查连接状态。当连接丢失时（在大多数情况下大约 4 分钟），我想等到连接再次恢复。在线和离线时间应该一直显示在控制台中。

感谢您的任何想法或帮助！

using WinSCP;

using (Session session = new Session())
{
    try
    {
        int i = 0;

        // Session Config
        SessionOptions sessionOptions = new SessionOptions
        {
            Protocol = Protocol.Sftp,
            HostName = "xxx.xx.xx.xx",
            UserName = "xxxxxx",
            Password = "xxxxxxxxx",
            SshHostKeyFingerprint = "xxxxxxxxxxxxxxxxxxxxxxxxxxxx",
        };
        // Connect
        session.Open(sessionOptions);

        while (true)
        {
            if (session.Opened == true) //this is displayed all the time
            {
                Console.WriteLine(i++ + "   " + DateTime.Now + "  " + "Online");
                // check again here if session.Opened still true? 
            }
            else if (session.Opened == false) 
            {
                Console.WriteLine(i++ + "   " + DateTime.Now + "  " + "Offline");
            }
        }
    }
    catch (Exception)
    {
   
    }
}

与

for

-循环：

using WinSCP;

for (int k = 0; k < 100; k++)
{
    using (Session session = new Session())
    {
        try
        {
            int i = 0;

            // Session Config
            SessionOptions sessionOptions = new SessionOptions
            {
                Protocol = Protocol.Sftp,
                HostName = "",
                UserName = "",
                Password = "",
                SshHostKeyFingerprint = "",
            };
            
            session.Open(sessionOptions);
            if (session.Opened == true)
            {
                Console.WriteLine(k + "    " + DateTime.Now + "     " + "Online");
                System.Threading.Thread.Sleep(1000);
                session.Close();
            }
            else if (session.Opened == false)
            {
                Console.WriteLine("Timeout");
                System.Threading.Thread.Sleep(1000);
            }

        }
        catch (Exception)
        {
            Console.WriteLine(k + "    " + DateTime.Now + "     " + "Offline");
        }
    }
}

Answer 1

Session

类不会主动检查连接。如果您在循环中不执行任何操作，它永远不会发现连接丢失。而且，如果连接丢失，也不会自动重新连接。

所以你必须

• 尝试对连接进行一些操作以确保它仍然处于活动状态
• 当连接丢失时，继续尝试重新连接

类似这样的：

DateTime lastChange = DateTime.Now;
Session session = null;
while (true)
{
    if (session == null)
    {
        session = new Session();
        try
        {
            session.Open(sessionOptions);
            lastChange = DateTime.Now;
        }
        catch (SessionException)
        {
            session.Dispose();
            session = null;
        }
    }
    else
    {
        try
        {
            session.FileExists(session.HomePath);
        }
        catch (SessionException)
        {
            lastChange = DateTime.Now;
            session.Dispose();
            session = null;
        }
    }

    var status = (session != null ? "Online" : "Offline");
    Console.WriteLine($"{status} for {DateTime.Now - lastChange}");

    Thread.Sleep(TimeSpan.FromSeconds(5));
}

输出示例：

Online for 00:00:00.0000067
Online for 00:00:05.0721274
Online for 00:00:10.1424717
Online for 00:00:15.2207413
Offline for 00:00:00.1085855
Offline for 00:00:10.2624759
Offline for 00:00:20.3726673
Online for 00:00:00.0000051
Online for 00:00:05.0674031

Answer 2

我认为这就是您正在寻找的：

using WinSCP;


using (Session session = new Session())
{
        try
        {
            int i = 0;

            // Session Config
            SessionOptions sessionOptions = new SessionOptions
            {
                Protocol = Protocol.Sftp,
                HostName = "xxx.xx.xx.xx",
                UserName = "xxxxxx",
                Password = "xxxxxxxxx",
                SshHostKeyFingerprint = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx",
            };
            // Connect
            session.Open(sessionOptions);

            while (true)
            {
              CheckConnectionStatus();
              //OPTIONAL:Thread.Sleep(5000)
            }
        }
        

        catch (Exception)
        {
       
        }
}

void CheckConnectionStatus()
{
  if (session.Opened)
  {
    Console.WriteLine(i++ + "   " + DateTime.Now + "  " + "Online");
  }
  else 
  {
    Console.WriteLine(i++ + "   " + DateTime.Now + "  " + "Offline");

    try
    {
      session.Open(sessionOptions);
    }
    catch { }
  }
}