mfc程序如何使用Windows API函数检测oracle数据库的连接状态，请写一段mfc程序能够调用的C++代码示例，谢谢

您好，根据您的要求，提供以下的MFC程序可以使用Windows API函数检测Oracle数据库的连接状态，所需的C代码也一并给出：

MFC程序示例：

#include <afxwin.h>
#include <windows.h>
#include <occi.h>
#include <iostream>

using namespace std;
using namespace oracle::occi;

class CMyApp : public CWinApp
{
public:
    virtual BOOL InitInstance();
};

class CMyFrame : public CFrameWnd
{
public:
    CMyFrame();
protected:
    afx_msg void OnConnectDB();  // 连接数据库按钮的消息处理函数
    DECLARE_MESSAGE_MAP()
};

BOOL CMyApp::InitInstance()
{
    CMyFrame* pFrame = new CMyFrame();
    m_pMainWnd = pFrame;
    pFrame->Create(NULL, _T("Oracle数据库状态检测"), WS_OVERLAPPEDWINDOW, CRect(50, 50, 600, 400), NULL, NULL);
    pFrame->ShowWindow(m_nCmdShow);
    pFrame->UpdateWindow();
    return TRUE;
}

CMyFrame::CMyFrame()
{
    Create(NULL, _T("Oracle数据库状态检测"), WS_OVERLAPPEDWINDOW, CRect(50, 50, 600, 400));
    CButton* pButton = new CButton();
    pButton->Create(_T("连接数据库"), WS_CHILD|WS_VISIBLE|BS_PUSHBUTTON, CRect(20, 20, 120, 40), this, 1);
}

void CMyFrame::OnConnectDB()
{
    Environment* env = Environment::createEnvironment();
    Connection* conn = env->createConnection("abc", "abc", "abc");
    try
    {
        if (conn->isClosed())
        {
            AfxMessageBox(_T("数据库连接已关闭！"));
        }
        else
        {
            AfxMessageBox(_T("数据库连接正常！"));
        }
        conn->terminateStatement();
    }
    catch (SQLException& ex)
    {
        cout << ex.getMessage() << endl;
    }
    env->terminateConnection(conn);
    Environment::terminateEnvironment(env);
}

BEGIN_MESSAGE_MAP(CMyFrame, CFrameWnd)
    ON_COMMAND(1, OnConnectDB)
END_MESSAGE_MAP()

CMyApp theApp;

C代码示例：

#include <oci.h>

int main()
{
    OCIEnv *envhp;
    OCIServer *srvhp;
    OCIError *errhp;
    boolean bConnected = TRUE;
    text *username = "abc";
    text *password = "abc";
    text *dbname = "abc";
    ub4 username_len = strlen((char*)username);
    ub4 password_len = strlen((char*)password);
    ub4 dbname_len = strlen((char*)dbname);

    OCIInitialize(OCI_DEFAULT, NULL, NULL, NULL, NULL);
    OCIEnvInit(&envhp, OCI_DEFAULT, 0, NULL);
    OCIHandleAlloc(envhp, (void**)&srvhp, OCI_HTYPE_SERVER, 0, NULL);
    OCIHandleAlloc(envhp, (void**)&errhp, OCI_HTYPE_ERROR, 0, NULL);
    OCIServerAttach(srvhp, errhp, (text*)dbname, dbname_len, 0);
    OCIAttrGet(srvhp, OCI_HTYPE_SERVER, &bConnected, 0, OCI_ATTR_SERVER_STATUS, errhp);
    if (!bConnected)
    {
        printf("数据库连接已关闭！\n");
    }
    else
    {
        printf("数据库连接正常！\n");
    }
    OCIServerDetach(srvhp, errhp, OCI_DEFAULT);
    OCIHandleFree(srvhp, OCI_HTYPE_SERVER);
    OCIHandleFree(errhp, OCI_HTYPE_ERROR);
    OCIEnvTerminate(envhp);
    return 0;
}

以上示例代码仅供参考，具体实现需要根据实际情况进行修改。