COM Tip(2)

一.使用IDispatch

interface IRandom : IDispatch
{
    import "oaidl.idl";
    [id(0)]
    HRESULT Start([out]long* pnID);
    [id(1)]
    HRESULT Stop([in]long nID);
    [id(2)]
    HRESULT StopAll();
};

使用GetIDsOfNames获取DISP

OLECHAR *fn=L"Stop";
DISPID id;
pRandom->GetIDsOfNames(IID_NULL,&fn,1,GetUserDefaultLCID(),&id);

使用Invoke动态调用函数

VARIANT var;
::VariantInit(&var);
var.lVal=2;

DISPPARAMS params;
params.cArgs=1;
params.rgvarg=&var;
pRandom->Invoke(id,IID_NULL,GetUserDefaultLCID(),DISPATCH_METHOD,
    &params,NULL,NULL,NULL);

跟反射的概念完全是一样的

二.IDispatchImpl

ATL中,IDispatchImpl实现了IDispatch

class CRandom :
    public IDispatchImpl<IRandom, &IID_IRandom, &LIBID_CONNECTLib>,
{
public:
    CRandom()
    {
    }
    ~CRandom();

BEGIN_COM_MAP(CRandom)
    COM_INTERFACE_ENTRY2(IDispatch, IRandom)
    COM_INTERFACE_ENTRY(IRandom)
END_COM_MAP()
}

三.实现连接点

1.实现IConnectionPointContainerImpl和IConnectionPointImpl

class CRandom :
    public IConnectionPointContainerImpl<CRandom>,
    public IConnectionPointImpl<CRandom, &IID_IRandomEvent, {
public:
    CRandom()
    {
    }
    ~CRandom();

BEGIN_COM_MAP(CRandom)
    COM_INTERFACE_ENTRY_IMPL(IConnectionPointContainer)
END_COM_MAP()

// Connection Point
    BEGIN_CONNECTION_POINT_MAP(CRandom)
        CONNECTION_POINT_ENTRY(IID_IRandomEvent)
    END_CONNECTION_POINT_MAP()
}

2.在客户端调用方实现IRandomEvent接口(接收器)

class CDriver :
    public IDispatchImpl<IRandomEvent, &IID_IRandomEvent, &LIBID_CONNECTLib>,
    public CComObjectRoot
{
public:
    CDriver() {}
BEGIN_COM_MAP(CDriver)
    COM_INTERFACE_ENTRY(IDispatch)
    COM_INTERFACE_ENTRY(IRandomEvent)
END_COM_MAP()

// IRandomEvent
    STDMETHOD(Fire)(long l);
public:
};

3.客户端创建连接点进行监听

CComObject<CDriver>* pDriver;
CComObject<CDriver>::CreateInstance(&pDriver);
pDriver->m_nID = m_nAdviseCnt;
HRESULT hRes = AtlAdvise(pRandom, pDriver->GetUnknown(), IID_IRandomEvent, &m_arrAdvise[m_nAdviseCnt++]);

4.服务器端进行回调

IConnectionPointImpl<CRandom, &IID_IRandomEvent, CComDynamicUnkArray>* p = this;
Lock();
HRESULT hr = S_OK;
IUnknown** pp = p->m_vec.begin();
while (pp < p->m_vec.end() && hr == S_OK)
{
    if (*pp != NULL)
    {
        IRandomEvent* pIRandomEvent = (IRandomEvent*)*pp;
        hr = pIRandomEvent->Fire(nID);
    }
    pp++;
}

5.自动生成连接点代理

第4步可以用vs自动生成代码,如果事件很多(而且客户端可以多次监听),写这些重复的代码是没有必要的

template<class T>
class CProxyIRandomEvent :
    public ATL::IConnectionPointImpl<T, &__uuidof(IRandomEvent)>
{
public:
    HRESULT Fire_Fire(long nID)
    {
        HRESULT hr = S_OK;
        T * pThis = static_cast<T *>(this);
        int cConnections = m_vec.GetSize();

        for (int iConnection = 0; iConnection < cConnections; iConnection++)
        {
            pThis->Lock();
            CComPtr<IUnknown> punkConnection = m_vec.GetAt(iConnection);
            pThis->Unlock();

            IRandomEvent * pConnection = static_cast<IRandomEvent *>(punkConnection.p);

            if (pConnection)
            {
                hr = pConnection->Fire(nID);
            }
        }
        return hr;
    }
};

class CRandom :
    public IDispatchImpl<IRandom, &IID_IRandom, &LIBID_CONNECTLib>,
    public IConnectionPointContainerImpl<CRandom>,
    public CProxyIRandomEvent<CRandom>
{
public:
    CRandom()
    {
    }
    ~CRandom();

// Connection Point1
    BEGIN_CONNECTION_POINT_MAP(CRandom)
        CONNECTION_POINT_ENTRY(__uuidof(IRandomEvent))
    END_CONNECTION_POINT_MAP()

让CRandom 继承自CProxyIRandomEvent,去掉之前的IConnectionPointImpl