Question

背景：

我有一个用ASP（VBScript）编写的遗留应用程序，它调用用VB6编写的COM组件。我们正在分阶段升级，需要首先将COM组件更新到.NET，同时保持与ASP的互操作性。

场合：

我创建了一个示例.NET类，并根据MSDN文档使用各种属性将其公开给COM系统
我能够实例化该课程
我可以在课程

问题：

参数值未发送到COM方法。例如所有数值类型在方法内都有值0;所有引用类型在方法内都具有null值。文字字符串正确传递给方法。但是，不传递字符串变量。
返回值的问题相同。无论方法返回什么值，ASP上的变量都有默认值（视情况而定为0或null）。

COM代码

<ComVisible(True)>
<InterfaceType(ComInterfaceType.InterfaceIsIDispatch)>
Public Interface IClass1
    Function Triple(ByVal input As String) As Integer
End Interface

<ComVisible(True)>
<ProgId("TESTCOM.Class1")>
<ClassInterface(ClassInterfaceType.None)>
Public Class Class1
    Inherits ServicedComponent
    Implements IClass1

    Public Sub New()
        ' needed for COM
    End Sub

    Public Function Triple(input As String) As Integer Implements IClass1.Triple
        IO.File.WriteAllText("C:\TestCOM.Class1_Triple.log", String.Format("[{0:s}] Input: {1}", Date.Now, input)) ''' this file is updated; so I know method is being called.
        Return 97
    End Function
End Class

备用COM代码

<ComVisible(True)>
<ProgId("TESTCOM.Class1")>
<ComClass("E26FE8A0-8AC7-4824-9776-30ECDD473AA3")>
Public Class Class1
    'Inherits ServicedComponent
    'Implements IClass1

    Public Sub New()
        ' needed for COM
    End Sub

    Private Const LogMessageFormat As String = "[{0:s}] Input: {1}, {2}" + vbCrLf

    Public Function Triple(csinput As String, nInput As Integer) As Integer 'Implements IClass1.Triple
        IO.File.AppendAllText("C:\TestCOM.Class1_Triple.log", 
                              String.Format(LogMessageFormat, Date.Now, if(csinput isnot Nothing, csinput, "**NULL**"), nInput))
        Return 97
    End Function
End Class

ASP代码

dim testNETCOM 
set testNETCOM = Server.CreateObject("TESTCOM.Class1")

' ** use this to check if there was any error during instantiation    
If Err.Number <> 0 Then
   Response.Redirect("http://"&Err.Description&"/")
  'Response.Write (Err.Description& "<br><br>")
else
    'Response.Redirect("http://no-error/")
End If
' ** use this to check if object is actually instantiated
if testNETCOM is nothing then
    Response.Redirect("http://no-com/")
else
    'Response.Redirect("http://yes-com/")
end if

dim nInput
set nInput = 41

dim nOutput
set nOutput = -1
set nOutput = CLng(testNETCOM.Triple("test message")) ' this string is received in the method
set nOutput = CLng(testNETCOM.Triple(CStr(nInput)))   ' this string is not received in the method

' ** use this to check if return value is what we expected
if nOutput <> 0 then
    Response.Redirect("http://test/")
else
    Response.Redirect("http://notest/") ''' **this happens**
end if

Answer 1

问题在于ASP

的语法

对于简单数据类型，请勿使用“set”
对于对象，请使用“set”

因为我使用set来表示简单类型，所以在赋值过程中出现了一个错误，并且变量的值为null / nothing / empty。

set nInput = 41 ' this is wrong
nInput = 41     ' this is right
set nOutput = CLng(testNETCOM.Triple(CStr(nInput))) ' this is wrong
nOutput = CLng(testNETCOM.Triple(CStr(nInput)))     ' this is right

Answer 2

尝试其中任何一个：

this.model.attributes.AcmeData.attributes.isEmpty

或者：

<ComVisible(True)> 
<Guid("79571A9D-2345-48D9-8F86-7F6761A97DBA")>
<InterfaceType(ComInterfaceType.InterfaceIsIDispatch)>
Public Interface IClass1
    Function Triple(ByVal input As String) As Integer
End Interface

<ComVisible(True)>
<Guid("E26FE8A0-8AC7-4824-9776-30ECDD473AA3")>
<ProgId("TESTCOM.Class1")>
<ClassInterface(ClassInterfaceType.None)>
Public Class Class1
    Inherits ServicedComponent
    Implements IClass1

    Public Sub New()
        ' needed for COM
    End Sub

    Public Function Triple(input As String) As Integer Implements IClass1.Triple
        IO.File.WriteAllText("C:\TestCOM.Class1_Triple.log", String.Format("[{0:s}] Input: {1}", Date.Now, input)) ''' this file is updated; so I know method is being called.
        Return 97
    End Function
End Class

方法调用从ASP到.NET COM失败

2 个答案: