版本：Visual Studio 6.0 + Service Pack 5 下的MFC6

文档类：CRichEditDoc的派生类

视图类：包括CRichEditView派生类及非CRichEditView派生类在内的多个视图

问题：程序在关闭文档时出错。

分析：

在CDocument里void CDocument::OnCloseDocument(){ while (!m_viewList.IsEmpty()) { // get frame attached to the view CView* pView = (CView*)m_viewList.GetHead(); ASSERT_VALID(pView); CFrameWnd* pFrame = pView->GetParentFrame(); ASSERT_VALID(pFrame); // and close it PreCloseFrame(pFrame); pFrame->DestroyWindow(); // will destroy the view as well } ......}在CRichEditDoc里CRichEditView* CRichEditDoc::GetView() const{ POSITION pos = GetFirstViewPosition(); if (pos == NULL) return NULL; // find the first view that is a CRichEditView CView* pView; while (pos != NULL) { pView = GetNextView(pos); if (pView->IsKindOf(RUNTIME_CLASS(CRichEditView))) return (CRichEditView*) pView; } // can't find one--return NULL return NULL;}void CRichEditDoc::PreCloseFrame(CFrameWnd* pFrameArg){ ...... // deactivate any inplace active items on this frame GetView()->m_lpRichEditOle->InPlaceDeactivate(); ................................................................1 ......}

可以发现，CDocument::OnCloseDocument在关闭每一个视图的时候总会调用PreCloseFrame来处理一些善后的工作，而CRichEditDoc::PreCloseFrame总调用CRichEditDoc::GetView() 来获得这些视图类的指针，但是CRichEditDoc::GetView() 只返回类型为CRichEditView派生类的视图对象的指针，这就造成CRichEditDoc::GetView() 在遇到非CRichEditView派生类的视图对象时候只是返回一个NULL，于是在1处程序出错，所以在这种情况下我们必须在CDocument::OnCloseDocument被调用之前手动关闭掉所有与CRichEditDoc相关联的非CRichEditView的派生类的视图。

我不知到这是不是微软特意这样做，总之在往CRichEditDoc里添加View后，关闭的时候都要先手动关闭其他不是CRichEditView派生出来的View,不知各位有什么见解^_^