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lrj2025kernel

[C++] 纯文本查看 复制代码

#include <iostream>
using namespace std;

#define ID_OPEN  100
#define ID_SAVE  101
#define ID_EXIT  102

class CCmdTarget
{
public:
	//要声明为虚函数，形成多态
	virtual bool OnCmdMsg(int id)
	{
		return false;
	}
};

class CDocument : public CCmdTarget
{
public:
	bool OnCmdMsg(int id) override
	{
		if (id == ID_SAVE)
		{
			cout << "CDocument::OnSave()" << endl;
			return true;
		}

		return CCmdTarget::OnCmdMsg(id);
	}
};

class CView : public CCmdTarget
{
	CDocument* m_pDoc;

public:
	CView(CDocument* doc) : m_pDoc(doc) {}

	bool OnCmdMsg(int id) override
	{
		cout << "CView::OnCmdMsg()" << endl;

		if (id == ID_OPEN)
		{
			cout << "CView::OnOpen()" << endl;
			return true;
		}

		// View 自己不处理
		// 转给 Document
		if (m_pDoc->OnCmdMsg(id))
			return true;

		return CCmdTarget::OnCmdMsg(id);
	}
};

class CWinApp : public CCmdTarget
{
public:
	bool OnCmdMsg(int id) override
	{
		if (id == ID_EXIT)
		{
			cout << "CWinApp::OnExit()" << endl;
			return true;
		}

		return CCmdTarget::OnCmdMsg(id);
	}
};

class CFrameWnd : public CCmdTarget
{
	CView* m_pView;
	CWinApp* m_pApp;

public:
	CFrameWnd(CView* view, CWinApp* app)
		: m_pView(view), m_pApp(app) {
	}

	bool OnCommand(int id)
	{
		cout << "CFrameWnd::OnCommand()" << endl;

		return OnCmdMsg(id);
	}

	bool OnCmdMsg(int id) override
	{
		cout << "CFrameWnd::OnCmdMsg()" << endl;

		// ① View
		if (m_pView->OnCmdMsg(id))
			return true;

		// ② Frame 自己
		if (CCmdTarget::OnCmdMsg(id))
			return true;

		// ③ App
		if (m_pApp->OnCmdMsg(id))
			return true;

		return false;
	}
};

int main()
{
	CWinApp app;
	CDocument doc;
	CView view(&doc);
	//这里暂时传入CView,实际中很可能是CView的派生类
	CFrameWnd frame(&view, &app);

	cout << "---- ID_OPEN ----" << endl;
	frame.OnCommand(ID_OPEN);

	cout << "\n---- ID_SAVE ----" << endl;
	frame.OnCommand(ID_SAVE);

	cout << "\n---- ID_EXIT ----" << endl;
	frame.OnCommand(ID_EXIT);

	cout << "\n---- ID_UNKNOWN ----" << endl;
	frame.OnCommand(999);

	system("pause");

	return 0;
}

bytebate

不错，加油！

ITHM

感谢作者分享，很厉害

zilong1988

谢谢分享