CLSIDFromProgID(L"Excel.Application", &clsid) 使用WIN32 API 读取Excel表格 封装工具类

可以使用以下步骤封装一个工具类：

1. 在类的头文件中添加必要的头文件和类声明：

#include <Windows.h>
#include <ole2.h>
#include <olectl.h>
#include <atlbase.h>

class ExcelReader {
public:
    ExcelReader();
    ~ExcelReader();

    bool OpenFile(const wchar_t* fileName);
    void CloseFile();
    bool ReadCell(int row, int col, wchar_t* value, int len);

private:
    void Init();
    void Uninit();

    bool GetActiveSheet();
    bool GetCell(int row, int col, IDispatch** cell);
    bool GetCellValue(IDispatch* cell, wchar_t* value, int len);

    CComPtr<IDispatch> m_pExcelApp;
    CComPtr<IDispatch> m_pWorkbook;
    CComPtr<IDispatch> m_pActiveSheet;
};

2. 在类的实现文件中添加必要的函数实现：

ExcelReader::ExcelReader() {
    Init();
}

ExcelReader::~ExcelReader() {
    Uninit();
}

void ExcelReader::Init() {
    CoInitialize(NULL);
    CLSID clsid;
    HRESULT hr = CLSIDFromProgID(L"Excel.Application", &clsid);
    if (SUCCEEDED(hr)) {
        hr = m_pExcelApp.CoCreateInstance(clsid);
        if (SUCCEEDED(hr)) {
            m_pExcelApp->PutVisible(VARIANT_FALSE);
        }
    }
}

void ExcelReader::Uninit() {
    CloseFile();
    m_pExcelApp.Release();
    CoUninitialize();
}

bool ExcelReader::OpenFile(const wchar_t* fileName) {
    if (!m_pExcelApp) {
        return false;
    }

    CloseFile();

    VARIANT result;
    VariantInit(&result);

    VARIANT file_name;
    VariantInit(&file_name);
    file_name.vt = VT_BSTR;
    file_name.bstrVal = SysAllocString(fileName);

    HRESULT hr = m_pExcelApp->GetWorkbooks()->Open(
        file_name,
        VARIANT(),
        VARIANT(),
        VARIANT(),
        VARIANT(),
        VARIANT(),
        VARIANT(),
        VARIANT(),
        VARIANT(),
        VARIANT(),
        VARIANT(),
        VARIANT(),
        VARIANT(),
        &result
    );

    VariantClear(&file_name);

    if (SUCCEEDED(hr)) {
        m_pWorkbook.Attach(result.pdispVal);
        return GetActiveSheet();
    }

    return false;
}

void ExcelReader::CloseFile() {
    m_pActiveSheet.Release();
    m_pWorkbook.Release();
}

bool ExcelReader::ReadCell(int row, int col, wchar_t* value, int len) {
    if (!m_pActiveSheet) {
        return false;
    }

    CComPtr<IDispatch> cell;
    if (!GetCell(row, col, &cell)) {
        return false;
    }

    return GetCellValue(cell, value, len);
}

bool ExcelReader::GetActiveSheet() {
    if (!m_pWorkbook) {
        return false;
    }

    VARIANT result;
    VariantInit(&result);

    HRESULT hr = m_pWorkbook->GetActiveSheet(&result);

    if (SUCCEEDED(hr)) {
        m_pActiveSheet.Attach(result.pdispVal);
        return true;
    }

    return false;
}

bool ExcelReader::GetCell(int row, int col, IDispatch** cell) {
    if (!m_pActiveSheet) {
        return false;
    }

    VARIANT result;
    VariantInit(&result);

    VARIANT vtRow;
    vtRow.vt = VT_INT;
    vtRow.intVal = row;

    VARIANT vtCol;
    vtCol.vt = VT_INT;
    vtCol.intVal = col;

    HRESULT hr = m_pActiveSheet->Invoke(
        DISPID_VALUE,
        IID_NULL,
        LOCALE_USER_DEFAULT,
        DISPATCH_PROPERTYGET,
        &result,
        NULL,
        NULL,
        NULL
    );

    if (SUCCEEDED(hr)) {
        CComPtr<IDispatch> range(result.pdispVal);
        hr = range->Invoke(
            DISPID_VALUE,
            IID_NULL,
            LOCALE_USER_DEFAULT,
            DISPATCH_METHOD,
            &result,
            NULL,
            NULL,
            NULL
        );
        if (SUCCEEDED(hr)) {
            *cell = result.pdispVal;
            return true;
        }
    }

    return false;
}

bool ExcelReader::GetCellValue(IDispatch* cell, wchar_t* value, int len) {
    VARIANT result;
    VariantInit(&result);

    HRESULT hr = cell->Invoke(
        DISPID_VALUE,
        IID_NULL,
        LOCALE_USER_DEFAULT,
        DISPATCH_PROPERTYGET,
        &result,
        NULL,
        NULL,
        NULL
    );

    if (SUCCEEDED(hr)) {
        if (result.vt == VT_BSTR) {
            wcsncpy_s(value, len, result.bstrVal, _TRUNCATE);
            VariantClear(&result);
            return true;
        }
    }

    return false;
}

3. 使用工具类读取 Excel 表格：

int main() {
    ExcelReader reader;
    if (!reader.OpenFile(L"example.xlsx")) {
        printf("Failed to open file.\n");
        return 1;
    }

    wchar_t value[256] = { 0 };
    if (reader.ReadCell(1, 1, value, sizeof(value) / sizeof(wchar_t))) {
        wprintf(L"Value of A1: %s\n", value);
    }

    reader.CloseFile();
    return 0;
}

这个工具类使用了 ATL 库来简化 COM 的使用，使用者只需要创建一个 ExcelReader 对象，调用 OpenFile 方法打开一个 Excel 文件，再调用 ReadCell 方法读取指定单元格的值即可。