根据表中数据动态生成菜单(三)

 

根据表中数据动态生成菜单(三)

本文讲述，如何通过数据库中的数据来动态生成菜单，如下：

1.创建对话框工程：DynamicMenuBornFromDatabase

2.本文使用ADO技术，因此需要导入一个ADO动态链接库msado15.dll，此库位于” Program Files/Common Files/System/ado/”。StdAfx.h中代码如下：

 #import "c:/Program Files/Common Files/System/ado/msado15.dll"

rename_namespace ("ADODB")/

rename ("EOF","ADOEOF")

usingnamespaceADODB ;

如果你的系统盘是其它盘，只需要修改以上路径即可。

3.为InitInstance()函数添加初始化连接数据库操作如下：

   //添加数据库连接

       AfxOleInit();

      

       m_pCon.CreateInstance(__uuidof(Connection));

       m_pRecord.CreateInstance(__uuidof(Recordset));

      

       m_pCon->ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0; /

              Data Source=./Menu.mdb;Persist Security Info=False";

       try

       {

              m_pCon->Open("","","",-1);

       }

       catch(...)

       {

              AfxMessageBox("数据库连接错误",0,0);

              exit;

       }

4.在CDynamicMenuBornFromDatabaseDlg类中添加如下成员变量：

    CMenu menu;

       HMENU h_menu ;

       HMENU h_submenu;

 CDynamicMenuBornFromDatabaseDlg实现中添加如下两个变量：

extern _ConnectionPtr m_pCon;

extern _RecordsetPtr m_pRecord;

添加两个全局变量如下：

_ConnectionPtr m_pCon;

_RecordsetPtr m_pRecord;

在OnInitDialog()中添加如下代码：

    menu.CreateMenu();

       LoadMenuFromDatabase();

5.在CDynamicMenuBornFromDatabaseDlg中添加如下三个成员函数如下：

 //判断指定的菜单是否有子菜单项

BOOL CDynamicMenuBornFromDatabaseDlg::IsHaveSubMenu(CString str)

{

       _ConnectionPtr m_con;

       _RecordsetPtr m_record;

       m_con.CreateInstance("ADODB.Connection");

       m_record.CreateInstance("ADODB.Recordset");

       m_con->ConnectionString = m_pCon->ConnectionString;

       m_con->Open("","","",-1);

       CString sql;

       sql.Format("select * from tb_menuinfo where 上级菜单 = '%s'",str);

       m_record = m_con->Execute((_bstr_t)sql,NULL,adCmdText);

       if ((!m_record->BOF) &&(! m_record->ADOEOF))

       {

              return TRUE;

       }

       return FALSE;

}

 

//从数据库中加载菜单

void CDynamicMenuBornFromDatabaseDlg::LoadMenuFromDatabase()

{

       CString sql;

       sql.Format( "select * from tb_menuinfo where 上级菜单 is NULL");

       m_pRecord = m_pCon->Execute((_bstr_t)sql,NULL,adCmdText);

       CMenu m_menu;

      

       CString c_menustr;

       while (! m_pRecord->ADOEOF)

       {

              c_menustr = m_pRecord->GetCollect("菜单名称").bstrVal;

              //menu.AppendMenu(MF_STRING,-1,c_menustr);

              LoadSubMenu(&menu,c_menustr); 

              m_pRecord->MoveNext();

       }

       SetMenu(&menu);

}

 

//利用递归的方式加载子菜单

void CDynamicMenuBornFromDatabaseDlg::LoadSubMenu(CMenu *m_menu, CString str)

{

       _ConnectionPtr m_con;

       _RecordsetPtr m_record;

       m_con.CreateInstance("ADODB.Connection");

       m_record.CreateInstance("ADODB.Recordset");

       m_con->ConnectionString = m_pCon->ConnectionString;

       m_con->Open("","","",-1);

       CString sql;

       sql.Format("select * from tb_menuinfo where 上级菜单 = '%s'",str);

       m_record = m_con->Execute((_bstr_t)sql,NULL,adCmdText);

       CMenu m_tempmenu;

       m_tempmenu.CreatePopupMenu();

      

       while (!m_record->ADOEOF)

       {

              CString c_menustr = m_record->GetCollect("菜单名称").bstrVal;

              m_tempmenu.AppendMenu(MF_STRING,-1,c_menustr);

              if (IsHaveSubMenu(c_menustr))

                     LoadSubMenu(&m_tempmenu,c_menustr);

              m_record->MoveNext();

       }

      

       m_menu->AppendMenu(MF_POPUP,(UINT)m_tempmenu.m_hMenu,str);

       m_tempmenu.Detach();

      

       if (m_record != NULL)

              m_record.Release();

       if (m_con!= NULL)

              m_con.Release();

}

编译运行，就可以看到效果了，可以根据数据库中的数据来生成菜单项。