BHO开发浏览器插件-Hello Word

             利用ATL框架开发BHO浏览器插件网上有不少资料，具体的过程就不写了。参考资料如下：

MSDN:https://msdn.microsoft.com/en-us/library/bb250489(v=vs.85).aspx

CSDN博客：http://blog.csdn.net/feier7501/article/details/11266345

按此种方法生成的插件，当打开网页时会弹出多个MessageBox，就是多次执行了OnDocumentComplete。

解决无果搜索如下文章：

《真正的DocumentComplete》：http://blog.csdn.net/skyremember/article/details/2994168

但代码是VB和MFC的，修改方法如下：

增加CHelloWorldBHO成员变量：

LPUNKNOWN m_lpUnknown;函数SetSite修改如下：
STDMETHODIMP CHelloWorldBHO::SetSite(IUnknown* pUnkSite)
{
if (pUnkSite != NULL)
{
// Cache the pointer to IWebBrowser2.
HRESULT hr = pUnkSite->QueryInterface(IID_IWebBrowser2, (void **)&m_spWebBrowser);
if (SUCCEEDED(hr))
{
// Register to sink events from DWebBrowserEvents2.
hr = DispEventAdvise(m_spWebBrowser);
if (SUCCEEDED(hr))
{
m_fAdvised = TRUE;
m_lpUnknown = pUnkSite;
}
}
}
else
{
// Unregister event sink.
if (m_fAdvised)
{
DispEventUnadvise(m_spWebBrowser);
m_fAdvised = FALSE;
m_lpUnknown= NULL;
}

// Release cached pointers and other resources here.
m_spWebBrowser.Release();
}

// Call base class implementation.
return IObjectWithSiteImpl<CMKeyBHO>::SetSite(pUnkSite);
}

OnDocumentComplete函数修改如下：

void STDMETHODCALLTYPE CHelloWorldBHO::OnDocumentComplete(IDispatch *pDisp, VARIANT *pvarURL)
{
HRESULT   hr;
//LPUNKNOWN lpUnknown;
LPUNKNOWN lpUnknownWB = NULL;
LPUNKNOWN lpUnknownDC = NULL;

//lpUnknown = m_spWebBrowser->GetControlUnknown();

//ASSERT(lpUnknown);

if (m_lpUnknown)
{
// Get the pointer to the IUnknown interface of the WebBrowser
// control being hosted. The pointer to the IUnknown returned from
// GetControlUnknown is not the pointer to the IUnknown of the
// WebBrowser control. It's actually a pointer to the IOleObject.
//
hr = m_lpUnknown->QueryInterface(IID_IUnknown,
(LPVOID*)&lpUnknownWB);

if (FAILED(hr))
return;

// Get the pointer to the IUnknown of the object that fired this
// event.
//
hr = pDisp->QueryInterface(IID_IUnknown,
(LPVOID*)&lpUnknownDC);

//ASSERT(SUCCEEDED(hr));

if (SUCCEEDED(hr) && lpUnknownWB == lpUnknownDC)
{
// The document has finished loading.
//
MessageBox(NULL, L"The document has finished loading.", L"", MB_OK);
}

if (lpUnknownWB)
lpUnknownWB->Release();

if (lpUnknownDC)
lpUnknownDC->Release();
}
}

这样改之后在网页加载完成的时才会弹出对话框，大功告成！