学步园

#include <iostream><br /> #include <atlbase.h><br /> using namespace std;</p> <p>interface IX : public IUnknown<br /> {<br /> virtual void _stdcall Fx() = 0;<br /> };</p> <p>interface IY : public IUnknown<br /> {<br /> virtual void _stdcall Fy() = 0;<br /> };</p> <p>interface IZ : public IUnknown<br /> {<br /> virtual void _stdcall Fz() = 0;<br /> };</p> <p>static const IID IID_IX = {0xff5ba880, 0xa371, 0x4a42, {0x87, 0x20, 0x96, 0xe0, 0x4d, 0x68, 0xd, 0x76}}; // {FF5BA880-A371-4a42-8720-96E04D680D76}<br /> static const IID IID_IY = {0xde44d538, 0xe926, 0x4d5f, {0x94, 0x5d, 0x61, 0x83, 0x86, 0x7c, 0x63, 0x41}}; // {DE44D538-E926-4d5f-945D-6183867C6341}<br /> static const IID IID_IZ = {0x91157d15, 0x22b1, 0x45d9, {0xb4, 0xc9, 0x81, 0x3, 0x8d, 0xec, 0xef, 0xad}}; // {91157D15-22B1-45d9-B4C9-81038DECEFAD}</p> <p>class CA : public IX,<br /> public IY<br /> {<br /> public:<br /> virtual HRESULT _stdcall QueryInterface(REFIID riid, __RPC__deref_out void **ppvObject);<br /> virtual ULONG _stdcall AddRef() { return 0; }<br /> virtual ULONG _stdcall Release() { return 0; }</p> <p> virtual void _stdcall Fx() { cout<<"IX::Fx"<<endl; }</p> <p> virtual void _stdcall Fy() { cout<<"IY::Fy"<<endl; }<br /> };</p> <p>HRESULT _stdcall CA::QueryInterface(REFIID riid, __RPC__deref_out void **ppvObject)<br /> {<br /> if(IID_IX == riid)<br /> {<br /> *ppvObject = static_cast<IX*>(this);<br /> }<br /> else if(IID_IY == riid)<br /> {<br /> *ppvObject = static_cast<IY*>(this);<br /> }<br /> else if(IID_IUnknown == riid)<br /> {<br /> //*ppvObject = static_cast<IUnknown*>(this); //这样为什么不行<br /> *ppvObject = static_cast<IX*>(this);<br /> }<br /> else<br /> {<br /> *ppvObject = NULL;<br /> return E_NOINTERFACE;<br /> }</p> <p> reinterpret_cast<IUnknown*>(*ppvObject)->AddRef();<br /> return S_OK;<br /> }</p> <p>IUnknown* CreateInstance()<br /> {<br /> IUnknown *pIUnk = static_cast<IX*>(new CA);<br /> pIUnk->AddRef();<br /> return pIUnk;<br /> }</p> <p>void _tmain(int argc,_TCHAR*argv[])<br /> {<br /> IUnknown *pIUnk = CreateInstance();</p> <p> IX *pIX = NULL;<br /> HRESULT hr = pIUnk->QueryInterface(IID_IX,(void**)&pIX);<br /> if(SUCCEEDED(hr))<br /> {<br /> pIX->Fx();<br /> }</p> <p> IY *pIY = NULL;<br /> hr = pIUnk->QueryInterface(IID_IY,(void**)&pIY);<br /> if(SUCCEEDED(hr))<br /> {<br /> pIY->Fy();<br /> }</p> <p> IZ *pIZ = NULL;<br /> hr = pIUnk->QueryInterface(IID_IZ,(void**)&pIZ);<br /> if(SUCCEEDED(hr))<br /> {<br /> cout<<"Succeed to find pIZ"<<endl;<br /> pIZ->Fz();<br /> }</p> <p> IY *pIYFromIX = NULL;<br /> hr = pIX->QueryInterface(IID_IY,(void**)&pIYFromIX);<br /> if(SUCCEEDED(hr))<br /> {<br /> pIYFromIX->Fy();<br /> }</p> <p> IUnknown *pIUnkFromIY = NULL;<br /> hr = pIY->QueryInterface(IID_IUnknown,(void**)&pIUnkFromIY);<br /> if(SUCCEEDED(hr))<br /> {<br /> if(pIUnkFromIY == pIUnk)<br /> cout<<"pIUnkFromIY == pIUnk"<<endl;<br /> else<br /> cout<<"pIUnkFromIY != pIUnk"<<endl;<br /> }</p> <p> if(pIUnk) delete pIUnk;<br /> }