使用COM，我如何确定为何不支持该接口。

问题描述

据我所知，这应该有效:::



ITypeLib Viewer输出：

库MyServerLib 
 {
 // TLib：OLE Automation：{00020430-0000-0000-C000-000000000046} 
 importlib（stdole2.tlb）; 
 
 //转发声明此typelib 
接口IOPCServer中定义的所有类型; 
接口IOPCBrowseServerAddressSpace; 
 ... 
 [
 uuid（E31E5782-636C-11D2-B326-0000A0080AC8），
 helpstring（OPC Server Class）
] 
 coclass OPCServer {
 [default] interface IOPCServer; 
接口IOPCBrowseServerAddressSpace; 
}; 
 
 [
 odl，
 uuid（39C13A4D-011E-11D0-9675-0020AFD8ADB3）
] 
 interface IOPCServer：IUnknown {
 HRESULT _stdcall AddGroup（..... 
}; 
 ... 
 
 [
 odl，
 uuid（39C13A4F-011E-11D0-9675- 0020AFD8ADB3）
] 
接口IOPCBrowseServerAddressSpace：IUnknown {
 HRESULT _stdcall QueryOrganization（[out] tagOPCNAMESPACETYPE * pNameSpaceType）; 
 .... 
}; 
 .... 
}; 

C ++代码::>

 const CLSID CLSID_OPCServer = {0xE31E5782,0x636C，0x11D2，{0xB3,0x26,0x00,0x00,0xA0,0x08,0x0A，0xC8}}; 
 const IID IID_IOPCBrowseServerAddressSpace = {0x39c13a4f，0x011e，0x11d0，{0x96 ，0x75,0x00,0x20,0xaf，0xd8,0xad，0xb3}}; 
 
 hr = CoInitializeEx（NULL，COINIT_MULTITHREADED）; 
 hr = CoCreateInstance（CLSID_OPCServer，NULL，CLSCTX_SERVER，
 IID_IUnknown，（void **）&（p2sPtrs-> pServer））; 
 //这是成功的并获得了一个pServer指针
 
 hr = p2sPtrs-> pServer-> QueryInterface（IID_IOPCBrowseServerAddressSpace，（void **）& m_spBrowse）; 
 //这个失败，没有支持这样的界面。

如何确定问题所在？

一切看起来都对我不错。

是否缺少一步？



我有什么试过：



尝试初始化

 COINIT_APARTMENTTHREADED 

没有区别。

解决方案

From my knowledge, this should work:::

ITypeLib Viewer output:

library MyServerLib
{
    // TLib : OLE Automation : {00020430-0000-0000-C000-000000000046}
    importlib("stdole2.tlb");

    // Forward declare all types defined in this typelib
    interface IOPCServer;
    interface IOPCBrowseServerAddressSpace;
    ...
    [
      uuid(E31E5782-636C-11D2-B326-0000A0080AC8),
      helpstring("OPC Server Class")
    ]
    coclass OPCServer {
        [default] interface IOPCServer;
        interface IOPCBrowseServerAddressSpace;
    };

    [
      odl,
      uuid(39C13A4D-011E-11D0-9675-0020AFD8ADB3)
    ]
    interface IOPCServer : IUnknown {
        HRESULT _stdcall AddGroup(.....
    };
	...

    [
      odl,
      uuid(39C13A4F-011E-11D0-9675-0020AFD8ADB3)
    ]
    interface IOPCBrowseServerAddressSpace : IUnknown {
        HRESULT _stdcall QueryOrganization([out] tagOPCNAMESPACETYPE* pNameSpaceType);
     ....
    };
    ....
};

C++ code::>

const CLSID CLSID_OPCServer = {0xE31E5782,0x636C,0x11D2,{0xB3,0x26,0x00,0x00,0xA0,0x08,0x0A,0xC8}};
	const IID IID_IOPCBrowseServerAddressSpace = { 0x39c13a4f,0x011e,0x11d0,{ 0x96,0x75,0x00,0x20,0xaf,0xd8,0xad,0xb3 } };

	 hr = CoInitializeEx(NULL, COINIT_MULTITHREADED);
	 hr = CoCreateInstance( CLSID_OPCServer, NULL, CLSCTX_SERVER,
											IID_IUnknown, (void **) &(p2sPtrs->pServer) );
	// this was successful and got a pServer pointer

	hr = p2sPtrs->pServer->QueryInterface(IID_IOPCBrowseServerAddressSpace, (void **)&m_spBrowse);
	// this fails with 'No such interface supported.'

How do I determine what the issue is?
Everything looks correct to me.
Is there a step missing?

What I have tried:

Tried initializing

COINIT_APARTMENTTHREADED

with no difference.

解决方案

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