C++ COM组件编写初探（下）

最新推荐文章于 2022-03-26 12:52:49 发布

转载最新推荐文章于 2022-03-26 12:52:49 发布 · 221 阅读

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原文链接：https://blog.youkuaiyun.com/shejiannan/article/details/26386271

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本文深入探讨了COM组件工厂的实现细节，包括QueryInterface、AddRef、Release等关键方法的运作原理，以及如何通过CreateInstance函数创建并返回指定接口的CompTestClass对象。此外，还介绍了LockServer函数的作用。

HRESULT _stdcall CompTestFactory::QueryInterface(const IID &riid, void **ppvObject)  
{  
    if (IID_IUnknown == riid){  
        *ppvObject = (IUnknown*)this;  
        ((IUnknown*)(*ppvObject))->AddRef();  
    }  
    else if (IID_IClassFactory == riid){  
        *ppvObject = (IClassFactory*)this;  
        ((IClassFactory*)(*ppvObject))->AddRef();  
    }  
    else{  
        *ppvObject = NULL;  
        return E_NOINTERFACE;  
    }  
    return S_OK;  
}  
  
ULONG _stdcall CompTestFactory::AddRef()  
{  
    m_Ref ++;  
    return m_Ref;  
}  
  
ULONG _stdcall CompTestFactory::Release()  
{  
    m_Ref --;  
    if (0 == m_Ref){  
        delete this;  
        return 0;  
    }  
    return m_Ref;  
}  
  
HRESULT _stdcall CompTestFactory::CreateInstance(IUnknown *pUnkOuter, const IID &riid, void **ppvObject)//最重要的函数，这个函数创建CompTestClass对象，并返回所需接口  
{  
    if (NULL != pUnkOuter){  
        return CLASS_E_NOAGGREGATION;  
    }  
    HRESULT hr = E_OUTOFMEMORY;  
    CompTestClass::Init();  
    CompTestClass* pObj = new CompTestClass();   
    if (NULL == pObj){  
        return hr;  
    }  
  
    hr = pObj->QueryInterface(riid, ppvObject);  
    if (S_OK != hr){  
        delete pObj;  
    }  
    return hr;  
}  
  
HRESULT _stdcall CompTestFactory::LockServer(BOOL fLock)  
{  
    return NOERROR;  
}

以下是客户程序的运行结果