Question

我正在尝试制作一个等待直到引发事件的代码。我在这个answer页面中使用了答案来进行Tcp通信。收到数据包时会引发event PacketReceived。

Private Sub FooBar()
    'Send some Tcp Message here`

    'Wait until a reply is received here

    'Execute some code when reply is received

End Sub

这是代码发送文件名以及文件的内容。它没有文件存在检查

Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
        Dim t = New Thread(AddressOf SendFile)
        Dim f = New FileAndData
        f.FileList = SlideShowItems
        f.FileType = "tempSlideShowImage"
        t.Start(f)
    End Sub

    Private Sub SendFile(obj As Object)
        Dim fD = CType(obj, FileAndData)
        For Each item In fD.FileList.Items
            Dim fileIn As New FileStream(item, FileMode.Open)
            Const chunkSize = 10485760

            Dim messageFileNamePkt As New TcpMessagePacket(Encoding.Default.GetBytes(Path.GetFileName(item)), TcpMessagePacket.PacketHeader.Filename)
            messageFileNamePkt.Send(_etcClient.Client) 'Send file name

            Dim messageFiletype As New TcpMessagePacket(Encoding.Default.GetBytes(fD.FileType), TcpMessagePacket.PacketHeader.Filetype)
            messageFiletype.Send(_etcClient.Client) 'Send file type

            'Wait here for reply if for file existence

            While fileIn.Position < fileIn.Length
                Dim bytes(chunkSize) As Byte
                If fileIn.Length - fileIn.Position < bytes.Length Then
                    ReDim bytes(fileIn.Length - fileIn.Position - 1)
                End If
                fileIn.Read(bytes, 0, bytes.Length)

                Dim messageFilePkt As New TcpMessagePacket(bytes, TcpMessagePacket.PacketHeader.FileData)
                messageFilePkt.Send(_etcClient.Client) 'Send file chunks

            End While

            fileIn.Close()
            Dim messageFileEnd As New TcpMessagePacket(Encoding.Default.GetBytes(""), TcpMessagePacket.PacketHeader.TransferComplete)
            messageFileEnd.Send(_etcClient.Client) 'Send transfer complete

        Next
    End Sub

Public Class FileAndData
    Public FileList As ListBox
    Public FileType As String
End Class

这是回复的处理程序

    Private Sub Client_PacketReceived(sender As Object, e As ExtendedTcpClient.PacketReceivedEventArgs) Handles _etcClient.PacketReceived
    End Sub

Answer 1

使用ManualResetEvent。实施例

Imports System.Threading
Module Module1
    Private ReadOnly WaitEvent As New ManualResetEvent(True)
    Sub Main()
        For i = 1 To 100
            WaitEvent.WaitOne() 'This is like a door. It's open because of ManualResetEvent(True)
            If i = 50 Then
                WaitEvent.Reset() 'This closes the door
            End If
            Console.WriteLine(i)
        Next
        Console.Read()
    End Sub
    Private Sub SetTheEventWhenCalled()
        WaitEvent.Set() 'This on the other hand, Opens the door
    End Sub
End Module

等待单位举起一个事件

1 个答案: