//AddRef和Release的实现
#include <iostream>
using namespace std;
#include <objbase.h>
void trace(const char* msg) { cout << msg << endl ;}
// Forward references for GUIDs
extern const IID IID_IX ;
extern const IID IID_IY ;
extern const IID IID_IZ ;
// Interfaces
interface IX : IUnknown
{
virtual void __stdcall Fx() = 0 ;
} ;
interface IY : IUnknown
{
virtual void __stdcall Fy() = 0 ;
} ;
interface IZ : IUnknown
{
virtual void __stdcall Fz() = 0 ;
} ;
//
// Component
//
class CA : public IX,
public IY
{
// IUnknown implementation
virtual HRESULT __stdcall QueryInterface(const IID& iid, void** ppv) ;
virtual ULONG __stdcall AddRef() ;
virtual ULONG __stdcall Release() ;
// Interface IX implementation
virtual void __stdcall Fx() { cout << "Fx" << endl ;}
// Interface IY implementation
virtual void __stdcall Fy() { cout << "Fy" << endl ;}
public:
// Constructor
CA() : m_cRef(0) {}
// Destructor
~CA() { trace("CA: Destroy self.") ;}
private:
long m_cRef;
} ;
HRESULT __stdcall CA::QueryInterface(const IID& iid, void** ppv)
{
if (iid == IID_IUnknown)
{
trace("CA QI: Return pointer to IUnknown.") ;
*ppv = static_cast<IX*>(this) ;
}
else if (iid == IID_IX)
{
trace("CA QI: Return pointer to IX.") ;
*ppv = static_cast<IX*>(this) ;
}
else if (iid == IID_IY)
{
trace("CA QI: Return pointer to IY.") ;
*ppv = static_cast<IY*>(this) ;
}
else
{
trace("CA QI: Interface not supported.") ;
*ppv = NULL ;
return E_NOINTERFACE;
}
reinterpret_cast<IUnknown*>(*ppv)->AddRef() ;
return S_OK ;
}
ULONG __stdcall CA::AddRef()
{
cout << "CA: AddRef = " << m_cRef+1 << '.' << endl ;
return InterlockedIncrement(&m_cRef) ;
}
ULONG __stdcall CA::Release()
{
cout << "CA: Release = " << m_cRef-1 << '.' << endl ;
if (InterlockedDecrement(&m_cRef) == 0)
{
delete this ;
return 0 ;
}
return m_cRef ;
}
//
// Creation function
//
IUnknown* CreateInstance()
{
IUnknown* pI = static_cast<IX*>(new CA) ;
pI->AddRef() ;
return pI ;
}
//
// IIDs
//
// {32bb8320-b41b-11cf-a6bb-0080c7b2d682}
static const IID IID_IX =
{0x32bb8320, 0xb41b, 0x11cf,
{0xa6, 0xbb, 0x0, 0x80, 0xc7, 0xb2, 0xd6, 0x82}} ;
// {32bb8321-b41b-11cf-a6bb-0080c7b2d682}
static const IID IID_IY =
{0x32bb8321, 0xb41b, 0x11cf,
{0xa6, 0xbb, 0x0, 0x80, 0xc7, 0xb2, 0xd6, 0x82}} ;
// {32bb8322-b41b-11cf-a6bb-0080c7b2d682}
static const IID IID_IZ =
{0x32bb8322, 0xb41b, 0x11cf,
{0xa6, 0xbb, 0x0, 0x80, 0xc7, 0xb2, 0xd6, 0x82}} ;
//
// Client
//
int main()
{
HRESULT hr ;
trace("Client: Get an IUnknown pointer.") ;
IUnknown* pIUnknown = CreateInstance() ;
trace("Client: Get interface IX.") ;
IX* pIX = NULL ;
hr = pIUnknown->QueryInterface(IID_IX, (void**)&pIX) ;
if (SUCCEEDED(hr))
{
trace("Client: Succeeded getting IX.") ;
pIX->Fx() ; // Use interface IX.
pIX->Release() ;
}
trace("Client: Get interface IY.") ;
IY* pIY = NULL ;
hr = pIUnknown->QueryInterface(IID_IY, (void**)&pIY) ;
if (SUCCEEDED(hr))
{
trace("Client: Succeeded getting IY.") ;
pIY->Fy() ; // Use interface IY.
pIY->Release() ;
}
trace("Client: Ask for an unsupported interface.") ;
IZ* pIZ = NULL ;
hr = pIUnknown->QueryInterface(IID_IZ, (void**)&pIZ) ;
if (SUCCEEDED(hr))
{
trace("Client: Succeeded in getting interface IZ.") ;
pIZ->Fz() ;
pIZ->Release() ;
}
else
{
trace("Client: Could not get interface IZ.") ;
}
trace("Client: Release IUnknown interface.") ;
pIUnknown->Release() ;
system("pause");
return 0;
}
本文转自Phinecos(洞庭散人)博客园博客，原文链接：http://www.cnblogs.com/phinecos/archive/2008/04/18/1159407.html，如需转载请自行联系原作者
