《COM技术内幕》笔记(二）

//AddRef和Release的实现
#include<iostream>
usingnamespacestd;
#include<objbase.h>

voidtrace(constchar*msg){cout<<msg<<endl;}

//ForwardreferencesforGUIDs
externconstIIDIID_IX;
externconstIIDIID_IY;
externconstIIDIID_IZ;

//Interfaces
interfaceIX:IUnknown
{
virtualvoid__stdcallFx()=0;
};

interfaceIY:IUnknown
{
virtualvoid__stdcallFy()=0;
};

interfaceIZ:IUnknown
{
virtualvoid__stdcallFz()=0;
};


//
//Component
//
classCA:publicIX,
publicIY
{
//IUnknownimplementation
virtualHRESULT__stdcallQueryInterface(constIID&iid,void**ppv);
virtualULONG__stdcallAddRef();
virtualULONG__stdcallRelease();

//InterfaceIXimplementation
virtualvoid__stdcallFx(){cout<<"Fx"<<endl;}

//InterfaceIYimplementation
virtualvoid__stdcallFy(){cout<<"Fy"<<endl;}

public:
//Constructor
CA():m_cRef(0){}

//Destructor
~CA(){trace("CA:Destroyself.");}

private:
longm_cRef;
};

HRESULT__stdcallCA::QueryInterface(constIID&iid,void**ppv)
{
if(iid==IID_IUnknown)
{
trace("CAQI:ReturnpointertoIUnknown.");
*ppv=static_cast<IX*>(this);
}
elseif(iid==IID_IX)
{
trace("CAQI:ReturnpointertoIX.");
*ppv=static_cast<IX*>(this);
}
elseif(iid==IID_IY)
{
trace("CAQI:ReturnpointertoIY.");
*ppv=static_cast<IY*>(this);
}
else
{
trace("CAQI:Interfacenotsupported.");
*ppv=NULL;
returnE_NOINTERFACE;
}
reinterpret_cast<IUnknown*>(*ppv)->AddRef();
returnS_OK;
}

ULONG__stdcallCA::AddRef()
{
cout<<"CA:AddRef="<<m_cRef+1<<'.'<<endl;
returnInterlockedIncrement(&m_cRef);
}

ULONG__stdcallCA::Release()
{
cout<<"CA:Release="<<m_cRef-1<<'.'<<endl;

if(InterlockedDecrement(&m_cRef)==0)
{
deletethis;
return0;
}
returnm_cRef;
}

//
//Creationfunction
//
IUnknown*CreateInstance()
{
IUnknown*pI=static_cast<IX*>(newCA);
pI->AddRef();
returnpI;
}

//
//IIDs
//
//{32bb8320-b41b-11cf-a6bb-0080c7b2d682}
staticconstIIDIID_IX=
{0x32bb8320,0xb41b,0x11cf,
{0xa6,0xbb,0x0,0x80,0xc7,0xb2,0xd6,0x82}};

//{32bb8321-b41b-11cf-a6bb-0080c7b2d682}
staticconstIIDIID_IY=
{0x32bb8321,0xb41b,0x11cf,
{0xa6,0xbb,0x0,0x80,0xc7,0xb2,0xd6,0x82}};

//{32bb8322-b41b-11cf-a6bb-0080c7b2d682}
staticconstIIDIID_IZ=
{0x32bb8322,0xb41b,0x11cf,
{0xa6,0xbb,0x0,0x80,0xc7,0xb2,0xd6,0x82}};

//
//Client
//
intmain()
{
HRESULThr;

trace("Client:GetanIUnknownpointer.");
IUnknown*pIUnknown=CreateInstance();


trace("Client:GetinterfaceIX.");

IX*pIX=NULL;
hr=pIUnknown->QueryInterface(IID_IX,(void**)&pIX);

if(SUCCEEDED(hr))
{
trace("Client:SucceededgettingIX.");
pIX->Fx();//UseinterfaceIX.
pIX->Release();
}


trace("Client:GetinterfaceIY.");

IY*pIY=NULL;
hr=pIUnknown->QueryInterface(IID_IY,(void**)&pIY);
if(SUCCEEDED(hr))
{
trace("Client:SucceededgettingIY.");
pIY->Fy();//UseinterfaceIY.
pIY->Release();
}


trace("Client:Askforanunsupportedinterface.");

IZ*pIZ=NULL;
hr=pIUnknown->QueryInterface(IID_IZ,(void**)&pIZ);
if(SUCCEEDED(hr))
{
trace("Client:SucceededingettinginterfaceIZ.");
pIZ->Fz();
pIZ->Release();
}
else
{
trace("Client:CouldnotgetinterfaceIZ.");
}


trace("Client:ReleaseIUnknowninterface.");
pIUnknown->Release();
system("pause");
return0;
}