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。