VB.Net Com Interop – 将COM事件接收到VBA客户端

发布时间：2020-12-17 07:18:14 所属栏目：百科来源：网络整理

导读：我在VB.NET中编写COM互操作DLL,我需要将事件暴露给VBA COM客户端.我无法绕过这一个. 这是.NET FTP库的COM包装器,所以不要因为我在BytesTransferred事件上引发BytesTransferred事件而感到困惑. 我最好回想一下,这段代码可以工作,但是当我使用对象浏览器时,它

我在VB.NET中编写COM互操作DLL,我需要将事件暴露给VBA COM客户端.我无法绕过这一个.

这是.NET FTP库的COM包装器,所以不要因为我在BytesTransferred事件上引发BytesTransferred事件而感到困惑.

我最好回想一下,这段代码可以工作,但是当我使用对象浏览器时,它无法在COM客户端中显示任何事件.当我尝试将变量WithEvents变暗时,它也无法编译：

Public Interface IFTP
    Event BytesTransferred(ByVal ByteCount As Long,ByVal RemoteFileName As String)
End Interface

'Here's the relevant part of my class:
Public Interface IFTP
    Event BytesTransferred(ByVal ByteCount As Long,ByVal RemoteFileName As String)
End Interface

Here's the relevant part of my class:

<ClassInterface(ClassInterfaceType.None)> _
    Public Class FTP : Implements IFTP

    Public Sub New()
        'This needed for com interop
    End Sub

    Public Event BytesTransferred(ByVal ByteCount As Long,ByVal RemoteFileName As String) Implements IFTP.BytesTransferred

    Private Sub fCon_BytesTransferred(ByVal sender As Object,ByVal e As EnterpriseDT.Net.Ftp.BytesTransferredEventArgs) Handles fCon.BytesTransferred
        RaiseEvent BytesTransferred(e.ByteCount,e.RemoteFile)
    End Sub

End Class

我也试过这样的东西,但我觉得我在这里遗漏了一些东西,因为它没有编译.我看到一个错误,表示我未能为接口IFTP实现Sub BytesTransferred：

Public Delegate Sub BytesTransferredDelegate(ByVal ByteCount As Long,ByVal RemoteFileName As String)

Public Interface IFTP
    <DispId(1)> _
    Sub BytesTransferred(ByVal ByteCount As Long,ByVal RemoteFileName As String)
End Interface

'Here's the relevant part of my class:

<ClassInterface(ClassInterfaceType.None)> _
    <ProgId("MyTestClass.FTP")> _
    <ComSourceInterfaces(GetType(IFTP))> _
Public Class FTP : Implements IFTP
    Public Event BytesTransferred As BytesTransferredDelegate

    Public Sub New()
        'This needed for com interop
    End Sub

    Private Sub fCon_BytesTransferred(ByVal sender As Object,e.RemoteFile)
    End Sub

End Class

解决方法

解：
1)在代码模块顶部声明Delegate Subs(带参数,如果需要)(如果你使用的话,在你的命名空间内)
2)为您的活动创建一个单独的界面,如下所示.请务必包含IDispatch声明
3)无需在主界面中为您的活动添加任何内容.
4)将ComSourceInterfaces声明与您的类声明一起使用
5)在您的课程中,使用“As”声明您的事件以指向您的Delegate Sub

如Hans Passant所述,请务必使用与VB6 / VBA兼容的数据类型. Long不是兼容的数据类型.

这是我现在的代码：

Public Delegate Sub BytesTransferredDelegate(ByVal ByteCount As Long,_
                    ByVal RemoteFileName As String)
Public Delegate Sub OnUploaded()

<InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIDispatch)> _
Public Interface IFTPEvents
    <DispId(1)> _
    Sub BytesTransferred(ByVal ByteCount As Double,_
                         ByVal RemoteFileName As String)
    <DispId(2)> _
    Sub Uploaded()
End Interface

Public Interface IFTP
    'Subs,Functions,Properties go here
    'No subs,functions,or events need to be declared here
    'to make our events work properly in COM
End Interface

<ComSourceInterfaces(GetType(IFTPEvents)),ClassInterface(ClassInterfaceType.None)> _
Public Class FTP : Implements IFTP
    Public Event BytesTransferred As BytesTransferredDelegate
    Public Event Uploaded As OnUploaded

    Public Sub New()
        'This needed for com interop
    End Sub

    Private Sub fCon_BytesTransferred(ByVal sender As Object,e.RemoteFile)
    End Sub

    Private Sub fCon_Uploaded(ByVal sender As Object,ByVal e As EnterpriseDT.Net.Ftp.FTPFileTransferEventArgs) Handles fCon.Uploaded
        RaiseEvent Uploaded()
    End Sub

End Class

这是我用来解决这个问题的来源：
http://msdn.microsoft.com/en-us/library/dd8bf0x3%28v=VS.90%29.aspx
http://www.codeproject.com/KB/COM/cominterop.aspx#UnmanagedSinks
http://www.developerfusion.com/tools/convert/csharp-to-vb/

（编辑：李大同）

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