OLE接口用法

转载请标明是引用于 http://blog.csdn.net/chenyujing1234

 例子代码:(编译工具：VS2005)

http://www.rayfile.com/zh-cn/files/4468c85c-7a4e-11e1-8329-0015c55db73d/

// 第一步得初始化COM环境
	HRESULT hr = CoInitialize(NULL);
	if (FAILED(hr)) 
	{
		return -3;
	}

// 第二步是获得接口 IDccMan
	hr = CoCreateInstance(CLSID_DccMan, NULL, CLSCTX_SERVER, IID_IDccMan, (LPVOID*)&g_pDccMan);
	if (FAILED(hr)) 
	{
		
		return -1;
	}

	// Create new notification object.
	g_pDanSink = new DanDccSink(hWnd, g_pDccMan);
	if (g_pDanSink)
	{
		// 第三步: 查询IDccManSink的接口
		g_pDanSink->QueryInterface(IID_IDccManSink, (void **)&pdms);

		// 这里调用后会自动调用OnLogActive函数
		g_pDccMan->Advise(pdms, &g_Context);
	}

g_pDanSink->QueryInterface(IID_IDccManSink, (void **)&pdms);，

1、会调用DanDccSink::QueryInterface，

STDMETHODIMP DanDccSink::QueryInterface(REFIID riid, LPVOID * ppvObj) 
{
	if (IID_IUnknown == riid || IID_IDccManSink == riid)
	{
		*ppvObj = (IDccManSink*)this;
	}
	else 
	{
		*ppvObj = NULL;
		return E_NOINTERFACE;
	}
	AddRef();

	return NO_ERROR;
}

它返回了(IDccManSink*)this;

// 第三步:这里调用后会自动调用OnLogActive函数
g_pDccMan->Advise(pdms, &g_Context);

1、它会先调用

STDMETHODIMP_(ULONG) DanDccSink::AddRef(THIS) 
{
	return (ULONG)InterlockedIncrement(&m_lRef);
}

2、然后又调用了一次QueryInterface,不过是返回了空接口.

3、调用调用

//
// The connection manager calls OnLogActive to indicate that the connection
// between the PC and the device is up and fully operational.
//
STDMETHODIMP DanDccSink::OnLogActiveC()
{

	return NO_ERROR;
}

4、然后又调用了一次QueryInterface,不过是返回了空接口.
5、然后调用

//
// When a connection is established, the connection manager calls OnLogIpAddr
// to notify you of the IP address of the connected device.
//
STDMETHODIMP DanDccSink::OnLogIpAddr(DWORD dwIpAddr) 
{
	TCHAR szIP[30];
	_stprintf_s(szIP, 30, TEXT("OnLogIpAddr: %02d.%02d.%02d.%02d"),
		(dwIpAddr & 0x000000ff),     (dwIpAddr & 0x0000ff00)>>8, 
		(dwIpAddr & 0x00ff0000)>>16, dwIpAddr>>24);

	//SendMessage(g_hwndStatusBar, SB_SETTEXT, (WPARAM)0, (LPARAM)szIP);

	return NO_ERROR;
}

下午很累了，具体原理下次补充.