c# - Outlook VSTO 加载项与外部 C++ 应用程序之间的交互

Question

我有一个 C++ 应用程序，我正在编写一个新的 Outlook 加载项，我认为它会与 VSTO 一起使用。我想在那之间进行交流，并且我正在尝试找出最好的方法。关于MS docs他们提到如何使用 RequestComAddInAutomationService 将您的 COM 类暴露给外部解决方案。我是 COM 的新手，但我在网上阅读了一些内容并找到了以下解决方案。我读到你应该构建插件(x86 作为我的 Outlook 版本而不是 AnyCPU)，获取创建的 .tlb 文件并将其转换为 .tlh 使用 #import 指令，然后使用 #include .tlh 文件以获得适当的类型。

ThisAddin.cs

namespace FirstOutlookAddIn
{

public partial class ThisAddIn
{
    Outlook.Inspectors inspectors;
    private AddInUtilities gUtilities;

    private void ThisAddIn_Startup(object sender, System.EventArgs e)
    {
        inspectors = this.Application.Inspectors;
        inspectors.NewInspector +=
        new Microsoft.Office.Interop.Outlook.InspectorsEvents_NewInspectorEventHandler(Inspectors_NewInspector);
    }

    void Inspectors_NewInspector(Microsoft.Office.Interop.Outlook.Inspector Inspector)
    {
        Outlook.MailItem mailItem = Inspector.CurrentItem as Outlook.MailItem;
        if (mailItem != null)
        {
            if (mailItem.EntryID == null)
            {
                gUtilities.SetMailItem(mailItem);
                mailItem.Subject = "This text was added by using code";
                mailItem.Body = "This text was added by using code";
            }

        }
    }

    protected override object RequestComAddInAutomationService()
    {
        if (gUtilities == null)
            gUtilities = new AddInUtilities();

        return gUtilities;
    }

    private void ThisAddIn_Shutdown(object sender, System.EventArgs e)
    {
        // Note: Outlook no longer raises this event. If you have code that 
        //    must run when Outlook shuts down, see https://go.microsoft.com/fwlink/?LinkId=506785
    }

    #region VSTO generated code

    /// <summary>
    /// Required method for Designer support - do not modify
    /// the contents of this method with the code editor.
    /// </summary>
    private void InternalStartup()
    {
        this.Startup += new System.EventHandler(ThisAddIn_Startup);
        this.Shutdown += new System.EventHandler(ThisAddIn_Shutdown);
    }

    #endregion
}

IAddInUtilities.cs

using System.Runtime.InteropServices;
namespace FirstOutlookAddIn
{
    [ComVisible(true)]
    public interface IAddInUtilities
    {
        void MyExportedFunction();
    }
}

AddInUtilities.cs

using Outlook = Microsoft.Office.Interop.Outlook;
using System.Runtime.InteropServices;
namespace FirstOutlookAddIn
{
    [ComVisible(true)]
    [ClassInterface(ClassInterfaceType.None)]
    public class AddInUtilities : StandardOleMarshalObject, IAddInUtilities
    {
        Outlook.MailItem globalMailItem;
        public void SetMailItem(Outlook.MailItem item) => globalMailItem = item;
        public void MyExportedFunction()
        {
            globalMailItem.Body = "I was called from outside!";
        }
    }
}

main.cpp

//#import "FirstOutlookAddIn.tlb" named_guids raw_interfaces_only

#include <iostream>
struct IUnknown; // Workaround for "combaseapi.h(229): error C2187: syntax error: 'identifier' was unexpected here" when using /permissive-
#include <Objbase.h>
#include "Debug\FirstOutlookAddIn.tlh"

int main() {
    CoInitializeEx(nullptr, COINIT_MULTITHREADED);
    FirstOutlookAddIn::IAddInUtilities* pIFace;
    // create the object and obtain a pointer to the sought interface
    auto res = CoCreateInstance(
        FirstOutlookAddIn::CLSID_AddInUtilities,
        nullptr,
        CLSCTX_LOCAL_SERVER,
        FirstOutlookAddIn::IID_IAddInUtilities,
        (LPVOID*)&pIFace);
    if (res != S_OK)
    {
        std::cout << "Failed with: " << res;
    }
    auto res1 = pIFace->MyExportedFunction(); // use the object
    std::cout << "Res: " << res1;
    pIFace->Release(); // free the object
    CoUninitialize();
}

问题是 CoCreateInstance 返回 REGDB_E_CLASSNOTREG 类未注册。相关的注册表树如下所示:

HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Classes\CLSID{5008A102-08E5-3F59-AADD-03875524CAD0} = FirstOutlookAddIn.AddInUtilities计算机\HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Classes\CLSID{5008A102-08E5-3F59-AADD-03875524CAD0}\InprocServer32: 计算机\HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Classes\CLSID{5008A102-08E5-3F59-AADD-03875524CAD0}\InprocServer32\1.0.0.0: Computer\HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Classes\CLSID{5008A102-08E5-3F59-AADD-03875524CAD0}\ProgId = FirstOutlookAddIn.AddInUtilities

我做错了什么？我是否正确理解了这里的可能性，将我的 DLL 加载到 Outlook.exe 中并能够从外部应用程序调用其中的函数？提前致谢!!!

Answer 1

您不应该从您的 C++ 应用程序创建该 COM 类的实例 - 创建 Outlook.Application 对象的实例，使用 Application.COMAddins 集合来获取您的插件，然后使用 COMAddin.Object 属性检索您的插件实现的接口(interface)。
参见，例如，https://blogs.msdn.microsoft.com/andreww/2007/01/15/vsto-add-ins-comaddins-and-requestcomaddinautomationservice/