VB.NET FTP登錄判斷超時

您好，以下是VB.NET实现FTP登录判断超时的示例代码：

Imports System.Net
Imports System.Net.Sockets

Public Class Form1
    Private ftpClient As New WebClient()
    Private ftpRequest As FtpWebRequest
    Private ftpResponse As FtpWebResponse
    Private ftpUri As Uri
    Private ftpTimeout As Integer = 5000 '设置超时时间为5秒

    Private Sub btnLogin_Click(sender As Object, e As EventArgs) Handles btnLogin.Click
        Try
            ftpUri = New Uri(txtFtpUrl.Text)
            ftpRequest = DirectCast(WebRequest.Create(ftpUri), FtpWebRequest)
            ftpRequest.Method = WebRequestMethods.Ftp.ListDirectory
            ftpRequest.Timeout = ftpTimeout '设置超时时间
            ftpRequest.Credentials = New NetworkCredential(txtUsername.Text, txtPassword.Text)
            ftpResponse = DirectCast(ftpRequest.GetResponse(), FtpWebResponse)
            MsgBox("登录成功！")
            ftpResponse.Close()
        Catch ex As WebException
            If ex.Status = WebExceptionStatus.Timeout Then
                MsgBox("连接超时！")
            Else
                MsgBox("登录失败：" & ex.Message)
            End If
        End Try
    End Sub
End Class

在上述代码中，我们通过设置FtpWebRequest的Timeout属性来实现超时判断。当连接超时时，会抛出WebException异常，并且WebException的Status属性值为WebExceptionStatus.Timeout。我们可以利用该属性值来判断连接是否超时。