Question

由于公司的限制，我有以下情况：

定义以下接口的COM库（没有CoClass，只是接口）：

[
    object,
    uuid(xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx),
    dual,
    nonextensible,
    helpstring("IService Interface"),
    pointer_default(unique)
]
IService : IDispatch
{
  HRESULT DoSomething();
}

[
    object,
    uuid(xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx),
    dual,
    nonextensible,
    helpstring("IProvider Interface"),
    pointer_default(unique)
]
IServiceProvider : IDispatch
{
  HRESULT Init( IDispatch *sink, VARIANT_BOOL * result );
  HRESULT GetService( LONG serviceIndicator, IService ** result );
};


[
    uuid(xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx),
    version(1.0),
]
library ServiceLibrary
{
    importlib("stdole2.tlb");

   interface IService;
   interface IServiceProvider;
};

我有一个COM（用C ++编写），它实现了两个接口，并为我们的应用程序提供了所述服务。一切都很好，我想。

我正在尝试在.NET（C＃）中构建新的IProvider和IService。

我为COM库构建了一个主Interop程序集，并实现了以下C＃：

[ComVisible( true )]
[Guid( "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" )]
public interface INewService : IService
{
   //  adds a couple new properties
}

[ComVisible( true )]
[Guid( "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" )]
public class NewService : INewService
{
   //  implement interface
}

[ComVisible( true )]
[Guid( "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" )]
public interface INewProvider : IServiceProvider
{
   //  adds nothing, just implements
}

[ComVisible( true )]
[Guid( "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" )]
public class NewProvider : INewProvider
{
   //  implement interface
}

当我尝试将其放入现有运行时时，我能够从COM（C ++）创建NewProvider对象，并为IServiceProvider创建QueryInterface。当我尝试在IServiceProvider上调用方法时，抛出System.ExecutionEngineException。

我能找到的唯一另一件事是查看#import创建的.tlh文件，显示遗留的COM IExistingProvider类正确显示它是从IServiceProvider派生的。但是，.NET类显示了IDispatch的基础。我不确定这是一个标志，指示，有用还是别的。

Answer 1

名称 IServiceProvider 可能存在问题。检查您是否尚未导入具有相同名称的接口。

当我使用您的IDL创建COM接口库，然后尝试从其他客户端导入它时，我收到警告：

Warning 65  warning C4192: automatically excluding 'IServiceProvider' while importing type library 'ServiceLibrary.dll'

否则，您可以尝试将其重命名为IServiceProvider2。这就是我所做的，一切正常。我正在使用Visual Studio 2008。

如果此代码在您的计算机上正常运行（它在我的计算机上运行正常），则问题可能出在您的实现中。

IDL：

import "oaidl.idl";

[
    object,
    uuid(9219CC5B-31CC-4868-A1DE-E18300F73C43),
    dual,
    nonextensible,
    helpstring("IService Interface"),
    pointer_default(unique)
]
interface IService : IDispatch
{
  HRESULT DoSomething(void);
}

[
    object,
    uuid(9219CC5B-31CC-4868-A1DE-E18300F73C44),
    dual,
    nonextensible,
    helpstring("IProvider Interface"),
    pointer_default(unique)
]
interface IServiceProvider2 : IDispatch
{
  HRESULT Init( IDispatch *sink, VARIANT_BOOL * result );
  HRESULT GetService( LONG serviceIndicator, IService ** result );
};

[
    uuid(9219CC5B-31CC-4868-A1DE-E18300F73C45),
    version(1.0),
]
library ServiceLibrary
{
    importlib("stdole2.tlb");

    interface IService;
    interface IServiceProvider2;
};

C＃：

using System.Runtime.InteropServices;
using System.Windows.Forms;
using ServiceLibrary;
using IServiceProvider=ServiceLibrary.IServiceProvider2;

namespace COMInterfaceTester
{
    [ComVisible(true)]
    [Guid("2B9D06B9-EB59-435e-B3FF-B891C63108B2")]
    public interface INewService : IService
    {
        string ServiceName { get; }
    }

    [ComVisible(true)]
    [Guid("2B9D06B9-EB59-435e-B3FF-B891C63108B3")]
    public class NewService : INewService
    {
        public string _name;

        public NewService(string name)
        {
            _name = name;
        }

        //  implement interface
        #region IService Members

        public void DoSomething()
        {
            MessageBox.Show("NewService.DoSomething");
        }

        #endregion

        public string ServiceName
        {
            get { return _name; }
        }
    }

    [ComVisible(true)]
    [Guid("2B9D06B9-EB59-435e-B3FF-B891C63108B4")]
    public interface INewProvider : IServiceProvider
    {
        //  adds nothing, just implements
    }

    [ComVisible(true)]
    [Guid("2B9D06B9-EB59-435e-B3FF-B891C63108B5")]
    public class NewProvider : INewProvider
    {
        //  implement interface
        public void Init(object sink, ref bool result)
        {
            MessageBox.Show("NewProvider.Init");
        }

        public void GetService(int serviceIndicator, ref IService result)
        {
            result = new NewService("FooBar");
            MessageBox.Show("NewProvider.GetService");
        }
    }
}

C ++客户端：

#include "stdafx.h"
#include <iostream>
#include <atlbase.h>
#import "COMInterfaceTester.tlb" raw_interfaces_only
#import "ServiceLibrary.dll" raw_interfaces_only

using std::cout;

int _tmain(int argc, _TCHAR* argv[])
{
    CoInitialize(NULL);   //Initialize all COM Components
    COMInterfaceTester::INewProviderPtr pNewProvider(__uuidof(COMInterfaceTester::NewProvider));
    ServiceLibrary::IServiceProvider2 *pNewProviderPtr;

    HRESULT hr = pNewProvider.QueryInterface(__uuidof(ServiceLibrary::IServiceProvider2), (void**)&pNewProviderPtr);

    if(SUCCEEDED(hr))
    {       
        VARIANT_BOOL result = VARIANT_FALSE;
        int *p = NULL;

        hr = pNewProviderPtr->Init((IDispatch*)p, &result);

        if (FAILED(hr))
        {
            cout << "Failed to call Init";
        }

        ServiceLibrary::IService *pService = NULL;
        hr = pNewProviderPtr->GetService(0, &pService);

        if (FAILED(hr))
        {
            cout << "Failed to call GetService";
        }
        else
        {
            COMInterfaceTester::INewService* pNewService = NULL;
            hr = pService->QueryInterface(__uuidof(COMInterfaceTester::INewService), (void**)&pNewService);

            if (SUCCEEDED(hr))
            {
                CComBSTR serviceName;
                pNewService->get_ServiceName(&serviceName); 

                if (serviceName == "FooBar")
                {
                    pService->DoSomething();
                }
                else
                    cout << "Unexpected service";

                pNewService->Release();

            }

            pService->Release();
        }

        pNewProviderPtr->Release();
    }
    else
        cout << "Failed to query for IServiceProvider2";

    pNewProvider.Release();
    CoUninitialize ();   //DeInitialize all COM Components

}

Answer 2

您可能必须在类上指定其他属性才能正确编组。我会查看可用的属性here，如果您还没有这样做，可以查看this tutorial。

在.NET中派生COM接口

2 个答案: