如何在 VB6 中使 VB.NET DLL 可调用？

Question

我用VB.NET在VS2017中做了一个DLL：

Imports System.Runtime.InteropServices

<ComClass(ComClass1.ClassId, ComClass1.InterfaceId, ComClass1.EventsId)>
Public Class ComClass1

#Region "COM GUIDs"
    ' These  GUIDs provide the COM identity for this class 
    ' and its COM interfaces. If you change them, existing 
    ' clients will no longer be able to access the class.
    Public Const ClassId As String = "c67bcd70-54d0-4498-97be-a5f954790dec"
    Public Const InterfaceId As String = "7ef1a8ce-bcc1-464e-8dc3-fc164bdb7ea3"
    Public Const EventsId As String = "9939eabd-1102-4e34-9735-54664e3536bd"
#End Region

    ' A creatable COM class must have a Public Sub New() 
    ' with no parameters, otherwise, the class will not be 
    ' registered in the COM registry and cannot be created 
    ' via CreateObject.
    Public Sub New()
        MyBase.New()
    End Sub

    Public Xposition As Int32

    Public GoX As Int32

    Public Function MoveX() As Int32
        Dim target As Int32
        target = Convert.ToInt32(Rnd() * 1000)
        Xposition = target
        Return Xposition
    End Function

    Public Function ReadX() As Int32
        Dim target As Int32
        target = Convert.ToInt32(Rnd() * 1000 - GoX)
        Xposition = target
        Return Xposition
    End Function

End Class

我在开发 Widows 10 PC 上以管理员身份编译了 DLL。 我将 DLL 文件复制到运行 VB6 的 Windows XP 目标机器并得到运行时错误 453。

VB6 代码：

Private Declare Function GSCloseServer Lib "GSWDLL32.DLL" () As Long

Private Declare Function MoveX Lib "C:\Temp\VB_Applications\My_DLL_Test\MyNewDLL.dll" () As Integer


Private Sub btnMove_Click()

Call test

End Sub

Private Sub btnStop_Click()

   Dim Running As Integer

  ' Unload MyGraph
   Set Form1 = Nothing
   Running = GSCloseServer()
   
   If Running = 0 Then
     MsgBox "Close Server OK: " & Running, vbOKOnly
   Else
     MsgBox "Close Server Error " & Running, vbOKOnly
   End If

   Unload Me
   
End Sub

Private Sub test()

'txtbxReadBack.Text = ComClass1.Xposition

txtbxReadBack.Text = MoveX

End Sub

我以管理员身份运行 VS2017，因此 DLL 似乎已在开发 PC 上正确注册。

Answer 1

这些是步骤。我将用一个类创建一个非常简单的“COMVisibleHelloWorld”类库

Imports System.Runtime.InteropServices

'Create a manual interface so we can use a fixed and known guid for the COM interface.
<Guid("3BBA8F8E-6B35-48E0-91D4-124DC6FCE7B9"), InterfaceType(ComInterfaceType.InterfaceIsDual)>
Public Interface IHelloWorld
    <DispId(1)> Function SayHello() As String

End Interface

<Guid("BCDCDA5C-DCAF-4C6C-86BA-03908DBEFF4B"), ClassInterface(ClassInterfaceType.None)>
Public Class HelloWorld
    Implements IHelloWorld

    Public Function SayHello() As String Implements IHelloWorld.SayHello
        Return "Hello World"
    End Function

End Class

在 Visual Studio 中选择“使程序集 COM 可见”

在 Visual Studio 中创建强键

构建项目。这将创建一个 tlb 文件。

您现在可以参考这是 VB6

要在 VB6 中使用，只需创建一个实例，然后调用具有 COM 接口的方法

Private Sub Command1_Click()

    Dim hello As New COMVisibleHelloWorld.HelloWorld
    MsgBox (hello.SayHello)

End Sub

结果：