使用Visual Basic编写一段代码,目的为尝试通过 Telnet 连接服务器时,出现连接超时会自动断开连接
时间: 2024-12-16 18:25:09 浏览: 55
在 Visual Basic 中,你可以使用 `System.Net.Sockets` 命名空间里的 `TcpClient` 类来实现 Telnet 连接。下面是一个基本示例,当连接超时时会自动关闭连接:
```vb.net
Imports System.Net.Sockets
Imports System.IO
Public Class TelnetConnection
Private Sub ConnectButton_Click(sender As Object, e As EventArgs) Handles ConnectButton.Click
Dim hostName As String = TextBoxServer.Text ' 获取服务器地址
Dim port As Integer = CInt(TextBoxPort.Text) ' 获取端口号
Try
' 创建 TcpClient 实例并尝试连接
Using client As New TcpClient(hostName, port)
' 输出连接成功信息
Console.WriteLine("Connected to " & hostName & ":" & port)
' 获取网络流以发送和接收数据
Using networkStream As NetworkStream = client.GetStream()
' 创建一个 StreamReader 和 StreamWriter 来读取和写入数据
Using reader As New StreamReader(networkStream, Encoding.ASCII)
Using writer As New StreamWriter(networkStream, Encoding.ASCII)
' 发送一些命令
writer.WriteLine("Hello from VB.NET")
' 接收并处理服务器响应
While Not reader.EndOfStream
Dim response As String = reader.ReadLine()
Console.WriteLine(response)
End While
End Using
End Using
End Using
End Using
Catch ex As IOException When ex.Message.Contains("A connection attempt failed because the connected party did not properly respond")
' 如果出现连接超时异常,捕获并关闭连接
Console.WriteLine("Connection timed out.")
Finally
' 关闭连接后可以安全地退出
If client IsNot Nothing Then
client.Close()
End If
End Try
End Sub
End Class
```
在这个示例中,`ConnectButton_Click` 事件处理程序负责实际的连接操作。如果遇到连接超时错误,控制台会打印出相应提示,并在 `Finally` 子句中关闭 `TcpClient`。
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