c# - access vba 中的 .net5 com 库

Question

我们有一个旧的 Access 工具需要打开用 C# 编写的 guis - Winforms。目前我们只是启动 exe，但如果可能的话，我想直接加载 dll。

到目前为止，我已经有了创建 com 可见库的代码

using System;
using System.Runtime.InteropServices;

namespace COMs {
    [ComVisible(true)]
    [Guid("C412E308-0D12-42D1-9506-C64A7958B4F9")]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    public interface IProduktionsstundenCOM {
        public void StartProduktionsstunden();
    }

    [ComVisible(true)]
    [Guid("C63D94CD-4978-40C2-AD88-799D9430683F")]
    public class ProduktionsstundenCOM : IProduktionsstundenCOM {

        public void StartProduktionsstunden() {
            throw new NotImplementedException();
        }
    }
}

它会构建并创建 .comhost.dll，然后我将其注册到 regsvr32 appname.comhost.dll。

这样做之后，我无法在 Access 引用窗口中找到该库，如果我浏览到它并尝试添加它，我会收到此错误“无法添加对所选文件的引用”(“Verweis auf die angegebene Datei kann nicht hinzugefügt韦登。”)。我能找到的唯一有用的文章是这篇 https://learn.microsoft.com/en-us/dotnet/core/native-interop/expose-components-to-com它还指出 .net5 无法创建 .tlb 文件，我什至不知道是否需要它们。

有没有办法让它工作？

Answer 1

我遇到了类似的问题并遇到了以下 github 存储库，它显示了 IDL 文件的外观。它还向您显示您将需要哪些额外的注册表项。您可以将其用作起点。 link

您的 IDL 文件的基本结构应如下所示:

[
    uuid(your library GUID),
    version(1.0),
    helpstring("ComTestLibrary")
]
library ComTestLibrary
{
    importlib("STDOLE2.TLB");

    [
        odl,
        uuid(your interface GUID),
        dual,
        oleautomation,
        nonextensible,
        helpstring("ComTestLibrary"),
        object,
    ]
    interface IComTest : IDispatch
    {
        [
            id(1),
            helpstring("Test")
        ]
        HRESULT Test(
            [in] double firstValue,
            [in] double secondValue,
            [in] BSTR comment,
            [out, retval] double* ReturnVal);

        // Other methods
    };

    [
        uuid(your class GUID),
        helpstring("ComTest")
    ]
    coclass ComTest
    {
        [default] interface IComTest;
    };
}

对于注册表项，您可以将 DllRegisterServer 和 DllUnregisterServer 函数添加到您的 COM 类中。在我的例子中，它们看起来像这样:

[ComRegisterFunction]
public static void DllRegisterServer(Type t)
{
      // Additional CLSID entries
      using (RegistryKey key = Registry.ClassesRoot.CreateSubKey(@"CLSID\{" + AssemblyInfo.ClassGuid + @"}"))
      {
           using (RegistryKey typeLib = key.CreateSubKey(@"TypeLib"))
           {
                typeLib.SetValue(string.Empty, "{" + AssemblyInfo.LibraryGuid + "}", RegistryValueKind.String);
           }
      }

      // Interface entries
      using (RegistryKey key = Registry.ClassesRoot.CreateSubKey(@"Interface\{" + AssemblyInfo.InterfaceGuid + @"}"))
      {
           using (RegistryKey typeLib = key.CreateSubKey(@"ProxyStubClsid32"))
           {
                typeLib.SetValue(string.Empty, "{00020424-0000-0000-C000-000000000046}", RegistryValueKind.String);
           }

           using (RegistryKey typeLib = key.CreateSubKey(@"TypeLib"))
           {
                typeLib.SetValue(string.Empty, "{" + AssemblyInfo.LibraryGuid + "}", RegistryValueKind.String);
                Version version = typeof(AssemblyInfo).Assembly.GetName().Version;
                typeLib.SetValue("Version", string.Format("{0}.{1}", version.Major, version.Minor), RegistryValueKind.String);
           }
      }

      // TypeLib entries
      using (RegistryKey key = Registry.ClassesRoot.CreateSubKey(@"TypeLib\{" + AssemblyInfo.LibraryGuid + @"}"))
      {
            Version version = typeof(AssemblyInfo).Assembly.GetName().Version;
            using (RegistryKey keyVersion = key.CreateSubKey(string.Format("{0}.{1}", version.Major, version.Minor)))
            {
                // typelib key for 32 bit
                keyVersion.SetValue(string.Empty, AssemblyInfo.Attribute<AssemblyDescriptionAttribute>().Description, RegistryValueKind.String);
                using (RegistryKey keyWin32 = keyVersion.CreateSubKey(@"0\win32"))
                {
                    keyWin32.SetValue(string.Empty, Path.ChangeExtension(Assembly.GetExecutingAssembly().Location, ".comhost.tlb"), RegistryValueKind.String);
                }

                // typelib key for 64 bit
                keyVersion.SetValue(string.Empty, AssemblyInfo.Attribute<AssemblyDescriptionAttribute>().Description, RegistryValueKind.String);
                using (RegistryKey keyWin64 = keyVersion.CreateSubKey(@"0\win64"))
                {
                    keyWin64.SetValue(string.Empty, Path.ChangeExtension(Assembly.GetExecutingAssembly().Location, ".comhost.tlb"), RegistryValueKind.String);
                }

                using (RegistryKey keyFlags = keyVersion.CreateSubKey(@"FLAGS"))
                {
                    keyFlags.SetValue(string.Empty, "0", RegistryValueKind.String);
                }
           }
      }
}

[ComUnregisterFunction]
public static void DllUnregisterServer(Type t)
{
        Registry.ClassesRoot.DeleteSubKeyTree(@"TypeLib\{" + AssemblyInfo.LibraryGuid + @"}", false);
        Registry.ClassesRoot.DeleteSubKeyTree(@"Interface\{" + AssemblyInfo.InterfaceGuid + @"}", false);
        Registry.ClassesRoot.DeleteSubKeyTree(@"CLSID\{" + AssemblyInfo.ClassGuid + @"}", false);
}