[原创]利用WM_COPYDATA实现进程间通信

进程间通信的方法有多种，其中，对于少量数据可以用WM_COPYDATA方便的实现通信(如果对于大量数据的话，由于SendMessage是阻塞的，只有接收方响应了消息，SendMessage才能返回，否则则一直阻塞，所以，对于大量数据来说，用SendMessage就容易造成窗口假死) 。

本例子分别用WM_COPYDATA 实现了两种数据类型的发送，一种为Cstring，另外一种为自定义的结构体Student：

//**********************************************************

 

#pragma pack(1)

struct Student {

       char ID[10];

       TCHAR   Name[20];

       UINT      Age;

       UINT      Grade;

       char Room[5];

       char Tel[12];

};

#pragma pack()

 

//**********************************************************

 

因为需要在接收方的OnCopyData()函数中区分发送的两种不同类型数据。所以就定义了以下两个常量：

#define STRING 1

#define STUDENT 2

 

 

 

发送方：

void CSendDataDlg::OnBtSend() //实现CString类型数据的发送

{

       UpdateData(TRUE);

       if (m_szData.IsEmpty()) {

              m_szData = _T("Hello");

              UpdateData(FALSE);

       }

//     m_szData += '\0';

       HWND hWndRcv = ::FindWindow(NULL,"Receiver");

       if (hWndRcv == NULL) {

              AfxMessageBox(_T("找不到接收窗口，发送不成功"));

              return ;

       }

       COPYDATASTRUCT cpd;

       cpd.dwData = STRING; //标志为CString类型

       cpd.cbData = m_szData.GetLength() + 1; 

       //GetLength()只是取得实际字符的长度，没有包括'\0'.

       cpd.lpData = (void*)m_szData.GetBuffer(cpd.cbData);

       ::SendMessage(hWndRcv,WM_COPYDATA,(WPARAM)this->m_hWnd,(LPARAM)&cpd);

       m_szData.ReleaseBuffer();

       AfxMessageBox(_T("发送成功"));

}

void CSendDataDlg::OnBtStu() //实现Student类型数据的发送

{

       UpdateData();

       m_szID += '\0';

       m_szName += '\0';

       m_szRoom += '\0';

       m_szTel += '\0';

       m_pStu = new Student();

       strcpy(m_pStu->ID,m_szID.GetBuffer(m_szID.GetLength()));

       _tcscpy(m_pStu->Name,m_szName.GetBuffer(m_szName.GetLength()));

       strcpy(m_pStu->Room,m_szRoom.GetBuffer(m_szRoom.GetLength()));

       strcpy(m_pStu->Tel,m_szTel.GetBuffer(m_szTel.GetLength()));

       m_szID.ReleaseBuffer();m_szName.ReleaseBuffer();

       m_szRoom.ReleaseBuffer();m_szTel.ReleaseBuffer();

       m_pStu->Age = m_nAge;

       m_pStu->Grade = m_nGrade;

       HWND hWndRcv = ::FindWindow(NULL,"Receiver");

       if (hWndRcv == NULL) {

              AfxMessageBox(_T("找不到接收窗口，发送不成功"));

              return ;

       } 

       COPYDATASTRUCT cpd;

       cpd.dwData = STUDENT;     // 标志为Student类型

       cpd.cbData = sizeof(Student);

       cpd.lpData = (PVOID)m_pStu;

       ::SendMessage(hWndRcv,WM_COPYDATA,(WPARAM)this->m_hWnd,(LPARAM)&cpd);

       delete m_pStu;

       AfxMessageBox(_T("发送成功"));

}

接收方：

在OnInitDialog方法中：

//***************************************************************

       //初始化ListCtrl控件

       LVCOLUMN column;

       column.mask = LVCF_TEXT | LVCF_SUBITEM | LVCF_WIDTH;

       column.cx = 80;

       column.iSubItem = 0;

       column.pszText = _T("ID");

       m_ListCtl.InsertColumn(0,&column);

       column.cx = 80;

       column.pszText = _T("Name");

       column.iSubItem = 1;

       m_ListCtl.InsertColumn(1,&column);

       column.cx = 55;

       column.pszText = _T("Age");

       column.iSubItem = 2;

       m_ListCtl.InsertColumn(2,&column);

       column.cx = 55;

       column.pszText = _T("Grade");

       column.iSubItem = 3;

       m_ListCtl.InsertColumn(3,&column);

       column.cx = 55;

       column.pszText = _T("Room");

       column.iSubItem = 4;

       m_ListCtl.InsertColumn(4,&column);

       column.cx = 80;

       column.pszText = _T("Tel");

       column.iSubItem = 5;

       m_ListCtl.InsertColumn(5,&column);

 

 

 

 

BOOL CReceiverDlg::OnCopyData(CWnd* pWnd, COPYDATASTRUCT* pCopyDataStruct)

{

       switch (pCopyDataStruct->dwData) { // 接收到的是CString类型

       case STRING:

              m_szData += (LPCSTR)(pCopyDataStruct->lpData);

              UpdateData(FALSE);

              break;

       case STUDENT:  // 接收到的是Student类型

              CString id,name,room,tel;

              UINT age,grade;

              CString str;

              Student* pStu = (Student*)(pCopyDataStruct->lpData);

              id = pStu->ID;

              name = pStu->Name;

              room = pStu->Room;

              tel = pStu->Tel;

              age = pStu->Age;

              grade = pStu->Grade;

              LVITEM item;

              // 把接收到的数据显示到ListCtrl控件上

              item.mask = LVIF_TEXT;

              int n = m_ListCtl.GetItemCount();

              item.iItem = n;

              item.iSubItem = 0;

              item.pszText = id.GetBuffer(id.GetLength());

              id.ReleaseBuffer();

              m_ListCtl.InsertItem(&item);

              m_ListCtl.SetItemText(n,1,name);

              str.Format("%d",age);

              m_ListCtl.SetItemText(n,2,str);

              str.Format("%d",grade);

              m_ListCtl.SetItemText(n,3,str);

              m_ListCtl.SetItemText(n,4,room);

              m_ListCtl.SetItemText(n,5,tel);           

              UpdateData(FALSE);

              //delete pStu;

              break;

       }

//     return CDialog::OnCopyData(pWnd, pCopyDataStruct);

       return TRUE;

}