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消息映射机制SDK编程中，一般处理消息的方法就是使用switch/case判断消息的类型，然后进行响应。更模块化的方法是使用第一章介绍的消息映射表的方法，把消息和消息处理函数关联起来。 应该为每个需要处理消息的类构建一个消息映射表，并将基类与派生类的消息映射表连接起来。当窗口函数比较消息时，就沿着这条继承路线传递下去。 为了实现这个目的我们仍然使用两个宏，完成这个功能复杂的构建。 首先定义一个数据结构： //消息映射表元素类型。 struct AFX_MSGMAP_ENTRY {
};
struct AFX_MSGMAP {
}; 在定义一个宏： define DECLARE_MESSAGE_MAP\
该宏相当于在类中声明两个static数据成员和一个虚成员函数。 它们的定义由以下三个宏实现： #define BEGIN_MESSAGE_MAP(class_name,base_class)\
#define ON_COMMAND(id,memFunc)\ WM_COMMAND,0,id,id,AFx_sig_vv\ ,(AFX_PMSG)memFunc },\
#define END_MESSAGE_MAP()\ {0,0,0,0,AfxSig_end,(AFX_PMSG)0}\ 以CView为例，下面的代码： class CWnd :public CWnd { public: DECLARE_MESSAGE_MAP()
};
展开后变为： class CView :public CWnd { public:
};
AFX_MSGMAP*CView::GetMessageMap()const {
} AFX_MSGMAP CView::messageMap= {
}; AFX_MSGMAP_ENTRY CView::_messageEntries[]= {
} 为了验证整个消息映射表，我们在每个类的消息映射表中添加了一个空的消息，这是为了做点标记，用于标示消息映射表的最后一个消息。MFC当然不是这样实现的。 /* CCmdTarget是消息传递的终点，因此在实现时需要特殊处理，这一点容易出错，要特别注意。 class CCmdTarget:public CObject {
public:
public: }; IMPLEMENT_DYNCREATE(CCmdTarget,CObject)
AFX_MSGMAP CCmdTarget::messageMap= {NULL,CCmdTarget::_messageEntries}; AFX_MSGMAP_ENTRY CCmdTarget::_messageEntries[]= { {0,0,10,0,AfxSig_end,0}, {0,0,0,0,AfxSig_end,0} }; AFX_MSGMAP*CCmdTarget::GetMessageMap()const { return &CCmdTarget::messageMap; } 以下为包含动态创建、类型识别、消息映射的完整代码： #include<iostream>
#include<windows.h>
#include<string>
using namespace std;
class CCmdTarget;
typedef void (CCmdTarget::*AFX_PMSG)(void);
//消息映射表元素类型。
enum AfxSig
{
AfxSig_end=0,
AfxSig_vv,
};
struct AFX_MSGMAP_ENTRY
{
UINT nMessage;
UINT nCode;
UINT nID;
UINT nLastID;
UINT nSig;
AFX_PMSG pfn;
};
struct AFX_MSGMAP
{
AFX_MSGMAP *pBaseMessageMap;//指向基类的本结构。
AFX_MSGMAP_ENTRY*lpEntries;//本类的消息映射表。
};
#define DECLARE_MESSAGE_MAP() public: static AFX_MSGMAP_ENTRY _messageEntries[]; static AFX_MSGMAP messageMap; virtual AFX_MSGMAP*GetMessageMap()const;
#define BEGIN_MESSAGE_MAP(class_name,base_class) AFX_MSGMAP*class_name::GetMessageMap()const {return &class_name::messageMap;} AFX_MSGMAP class_name::messageMap={&base_class::messageMap,class_name::_messageEntries}; AFX_MSGMAP_ENTRY class_name::_messageEntries[]= {
#define ON_COMMAND(id,memFunc) {WM_COMMAND,0,id,id,AfxSig_vv,(AFX_PMSG)memFunc },
#define END_MESSAGE_MAP() {0,0,0,0,AfxSig_end,(AFX_PMSG)0} };
class CObject;
class CRuntimeClass
{
public:
char* m_lpszClassName;//对象所属类名
int m_nObjectSize;//对象大小
int m_wSchema;//模式号
CObject*(PASCAL*m_pfnCreateObject)();//构建函数,抽象类为NULL
CRuntimeClass *m_pBaseClasss;//基类CRuntimeClass对象指针。
static CRuntimeClass *pFirstClass;//链表头指针。static
CRuntimeClass *m_pNextClass;//下一指针。
public:
CObject*CreateObject()
{
if(m_pfnCreateObject==NULL)
{
cout<<"该类型不支持动态创建！！"<<endl;
return NULL;
}
CObject*pClass=(*m_pfnCreateObject)();
return pClass;
}
static CRuntimeClass*Load()
{
cout<<"请输入要动态创建的类名：";
string s;
cin>>s;
for(CRuntimeClass*pClass=pFirstClass;pClass;pClass=pClass->m_pBaseClasss)
{
if(pClass->m_lpszClassName==s)
{
return pClass;
}
}
return NULL;
}
};
class AFX_CLASSINIT
{
public:
AFX_CLASSINIT(CRuntimeClass*pNewClass)//构造函数
{
pNewClass->m_pNextClass=CRuntimeClass::pFirstClass;
CRuntimeClass::pFirstClass =pNewClass;
}
};
/************************************************************************/
/* 动态类型识别宏定义
//与CRuntimeClass类中的构建函数相区别。此处的CreateObject函数在每个类中都以static成员函数存在，用以
//初始化类型型录表，而CRuntimeClass中的CreateObject用于调用每个类的构建函数。仅仅是函数名相同罢了。*/
/************************************************************************/
#define DECLARE_DYNAMIC(class_name) public: static CRuntimeClass Class##class_name; virtual CRuntimeClass*GetRuntimeClass()const;
#define DECLARE_DYNCREATE(class_name) DECLARE_DYNAMIC(class_name) static CObject*PASCAL CreateObject();
#define RUNTIME_CLASS(class_name) (&class_name::Class##class_name)
#define _IMPLEMENT_RUNTIMECLASS(class_name,base_class_name,wSchema,pfnNew) class CRuntimeClass class_name::Class##class_name ={ #class_name, sizeof(class_name),wSchema,pfnNew,RUNTIME_CLASS(base_class_name),NULL}; static AFX_CLASSINIT _init##class_name( RUNTIME_CLASS(class_name)); CRuntimeClass *class_name::GetRuntimeClass()const {return &class_name::Class##class_name;}//此处将class_name写成了classname花了一两天才查出来。啊啊啊啊啊。20120605
#define IMPLEMENT_DYNAMIC(class_name,base_class_name) _IMPLEMENT_RUNTIMECLASS(class_name,base_class_name,0xFFFF,NULL)
#define IMPLEMENT_DYNCREATE(class_name,base_class_name) CObject*PASCAL class_name::CreateObject(){return new class_name;} _IMPLEMENT_RUNTIMECLASS(class_name,base_class_name,0xFFFF,class_name::CreateObject)
/************************************************************************/
/* 对CObject特殊处理。 */
/************************************************************************/
class CObject
{
public:
CObject()
{
//cout<<"CObject constructor!"<<endl;
}
~CObject()
{
//cout<<"CObject destructor!"<<endl;
}
public:
virtual CRuntimeClass*GetRuntimeClass();
static CRuntimeClass ClassCObject;
public:
bool IsKindOf(CRuntimeClass*pClass)
{
CRuntimeClass *pThis=GetRuntimeClass();
for(;pThis;pThis=pThis->m_pBaseClasss)
{
if(pThis==pClass)
{
return true;
}
}
return false;
}
};
class CRuntimeClass CObject:: ClassCObject=
{
"CObject",sizeof(CObject),0xFFFF,NULL,NULL,NULL
};
static AFX_CLASSINIT _init_CObject(&CObject:: ClassCObject);
CRuntimeClass *CObject::GetRuntimeClass()
{
return &CObject::ClassCObject;
}
CRuntimeClass*CRuntimeClass::pFirstClass=NULL;
/************************************************************************/
/* CCmdTarget是消息传递的终点，因此在实现时不能使用BEGIN_MESSAGE_MAP */
/************************************************************************/
class CCmdTarget:public CObject
{
DECLARE_DYNCREATE(CCmdTarget)
DECLARE_MESSAGE_MAP()
public:
CCmdTarget()
{
//cout<<"CCmdTarget constructor!"<<endl;
//CreateObject();
}
~CCmdTarget()
{
//cout<<"CCmdTarget destructor!"<<endl;
}
public:
};
IMPLEMENT_DYNCREATE(CCmdTarget,CObject)
AFX_MSGMAP CCmdTarget::messageMap=
{NULL,CCmdTarget::_messageEntries};
AFX_MSGMAP_ENTRY CCmdTarget::_messageEntries[]=
{
{0,0,10,0,AfxSig_end,0},
{0,0,0,0,AfxSig_end,0}
};
AFX_MSGMAP*CCmdTarget::GetMessageMap()const
{
return &CCmdTarget::messageMap;
}
class CWnd:public CCmdTarget
{
DECLARE_DYNCREATE(CWnd)
DECLARE_MESSAGE_MAP()
public:
CWnd()
{
//cout<<"CWnd constructor"<<endl;
}
~CWnd()
{
//cout<<"CWnd destructor"<<endl;
}
public:
virtual bool Create()
{
cout<<"CWnd::Create"<<endl;
CreateEx();
return true;
}
bool CreateEx()
{
cout<<"CWnd::CreateEx"<<endl;
PreCreateWindow();
return true;
}
virtual bool PreCreateWindow()
{
cout<<"CWnd::PreCreateWindow"<<endl;
return true;
}
};
IMPLEMENT_DYNCREATE(CWnd,CCmdTarget)
class CView :public CWnd
{
DECLARE_DYNCREATE(CView)
DECLARE_MESSAGE_MAP()
public:
CView()
{
//cout<<"CView constructor"<<endl;
}
~CView()
{
//cout<<"CView destructor"<<endl;
}
};
IMPLEMENT_DYNCREATE(CView,CWnd)
class CFrameWnd:public CWnd
{
DECLARE_DYNCREATE(CFrameWnd)
DECLARE_MESSAGE_MAP()
public:
CFrameWnd()
{
//cout<<"CFrameWnd constructor"<<endl;
}
~CFrameWnd()
{
//cout<<"CFrameWnd destructor"<<endl;
}
public:
virtual bool Create()
{
cout<<"CFrameWnd::Create"<<endl;
CreateEx();
return true;
}
virtual bool PreCreateWindow()
{
cout<<"CFrameWnd::PreCreateWindow"<<endl;
return true;
}
};
IMPLEMENT_DYNCREATE(CFrameWnd,CWnd)
class CWinThread:public CCmdTarget
{
public:
CWinThread()
{
//cout<<"CWinThread constructor"<<endl;
}
~CWinThread()
{
//cout<<"CWinThread destructor"<<endl;
}
public:
virtual bool InitInstance()
{
cout<<"CWinThread::InitInstance"<<endl;
return true;
}
virtual bool Run()
{
cout<<"CWinThread::Run"<<endl;
return true;
}
};
class CWinApp:public CWinThread
{
DECLARE_MESSAGE_MAP()
public:
CWinApp()
{
//cout<<"CWinApp Constructor "<<endl;
m_currentApp=this;
}
~CWinApp()
{
//cout<<"CWinApp destructor "<<endl;
}
virtual bool InitApplication()
{
cout<<"CWinApp::InitApplication"<<endl;
return true;
}
virtual bool InitInstance()
{
cout<<"CWinApp:InitInstance"<<endl;
return true;
}
virtual bool Run()
{
cout<<"CWinApp::Run"<<endl;
return CWinThread::Run();
}
public:
CWinApp*m_currentApp;
CFrameWnd*m_currentFrameWnd;
};
class CDocument:public CCmdTarget
{
DECLARE_MESSAGE_MAP()
public:
CDocument()
{
//cout<<"CDocument constructor "<<endl;
}
~CDocument()
{
//cout<<"CDocunment destructor "<<endl;
}
};
class CMyFrameWnd:public CFrameWnd
{
DECLARE_DYNCREATE(CMyFrameWnd)
DECLARE_MESSAGE_MAP()
public:
CMyFrameWnd()
{
//cout<<"CMyFrameWnd constructor "<<endl;
Create();
}
~CMyFrameWnd()
{
//cout<<"CMyFrameWnd destructor "<<endl;
}
};
IMPLEMENT_DYNCREATE(CMyFrameWnd,CFrameWnd)
class CMyWinApp:public CWinApp
{
DECLARE_MESSAGE_MAP()
public:
CMyWinApp()
{
//cout<<"CMyWinApp constructor "<<endl;
}
~CMyWinApp()
{
//cout<<"CMyWinApp destructor "<<endl;
}
public:
bool InitInstance()
{
cout<<"CMyWinApp::InitInstance"<<endl;
m_currentFrameWnd=new CMyFrameWnd;
return true;
}
};
BEGIN_MESSAGE_MAP(CWnd,CCmdTarget)
ON_COMMAND(1,0)
END_MESSAGE_MAP()
BEGIN_MESSAGE_MAP(CFrameWnd,CWnd)
ON_COMMAND(2,0)
END_MESSAGE_MAP()
BEGIN_MESSAGE_MAP(CDocument,CCmdTarget)
ON_COMMAND(3,0)
END_MESSAGE_MAP()
BEGIN_MESSAGE_MAP(CView,CWnd)
ON_COMMAND(4,0)
END_MESSAGE_MAP()
BEGIN_MESSAGE_MAP(CWinApp,CCmdTarget)
ON_COMMAND(5,0)
END_MESSAGE_MAP()
BEGIN_MESSAGE_MAP(CMyWinApp,CWinApp)
ON_COMMAND(6,0)
END_MESSAGE_MAP()
BEGIN_MESSAGE_MAP(CMyFrameWnd,CFrameWnd)
ON_COMMAND(7,0)
END_MESSAGE_MAP()
CMyWinApp myApp;
CWinApp*AfxGetApp()
{
return myApp.m_currentApp;
}
void printAllMsgMapping(AFX_MSGMAP*p)
{
for(;p;p=p->pBaseMessageMap)
{
for(int i=0;p->lpEntries[i].nID;i++)
{
cout<<p->lpEntries[i].nID<<endl;
}
}
}
int main(int argc,char**argv)
{
CWinApp *pApp=AfxGetApp();
pApp->InitApplication();
pApp->InitInstance();
pApp->Run();
CRuntimeClass *pClass;
CObject *pOb;
cout<<"以下为类型型录链表中的所有类的名称："<<endl;
for(pClass=CRuntimeClass::pFirstClass;pClass;pClass=pClass->m_pBaseClasss)
{
cout<<pClass->m_lpszClassName<<endl;
}
CMyFrameWnd *pMyFrame=(CMyFrameWnd*)pApp->m_currentFrameWnd;
printAllMsgMapping(pMyFrame->GetMessageMap());
cout<<endl;
CDocument *pDoc=new CDocument;
printAllMsgMapping(pDoc->GetMessageMap());
while(1)
{
pClass=CRuntimeClass::Load();
if(!pClass)
{
cout<<"找不到此类！！！"<<endl;
}
else
{
pOb=pClass->CreateObject();
if(pOb)
{
cout<<"创建成功！"<<endl;
}
}
}
return 0;
}
原文链接：http://blog.csdn.net/ithzhang/article/details/7635945 |
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