c# - 如何关闭由 spire.xls 创建的文件

Question

我正在将 CSV 文档转换为 PDF，如 Spire.XLS 的代码所示。问题是文件在创建后仍然打开，我无法在程序运行时删除它。那么有谁知道我如何在不关闭漏洞程序的情况下关闭这个文件？

//check if open = false
        if (IsFileinUse())
        {
            Console.WriteLine("PDF open btn_ConvertToPDF_Click");
        }
        else
        {
            Console.WriteLine("PDF closed btn_ConvertToPDF_Click");
        }

        //code that creates the file but does not close it
        Workbook wb = new Workbook();
        wb.LoadFromFile(filename + ".csv", ",");
        wb.ConverterSetting.SheetFitToPage = true;
        Worksheet sheet = wb.Worksheets[0];
        for (int i = 1; i < sheet.Columns.Length; i++)
        {
            sheet.AutoFitColumn(i);
        }
        sheet.SaveToPdf(filename+".pdf");

        //check if open = true
        if (IsFileinUse())
        {
            Console.WriteLine("PDF open btn_ConvertToPDF_Click");
        }
        else
        {
            Console.WriteLine("PDF closed btn_ConvertToPDF_Click");
        }