在不使用Office组件的情况下将xls转换为xlsx时格式丢失

Question

我一直试图将.xls文件转换为.xlsx，而不必依赖Office组件。我关注了c-sharp-convert-xls-file-to-xlsx-without-office-components

它将文件从xls转换为xlsx，但所有格式均丢失。我尝试了其他库，例如Spire.XLS，NPOI等。但是没有一个库可以将.xls精确复制到.xlsx。请帮助我进行格式化。以下是我用于转换的链接中的代码：

XLWorkbook workbook = new XLWorkbook();
        DataSet ds = new DataSet();

        string connectionString = GetConnectionString();

        using (OleDbConnection conn = new OleDbConnection(connectionString))
        {
            conn.Open();
            OleDbCommand cmd = new OleDbCommand();
            cmd.Connection = conn;

            // Get all Sheets in Excel File
            DataTable dtSheet = conn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);

            // Loop through all Sheets to get data
            foreach (DataRow dr in dtSheet.Rows)
            {
                string sheetName = dr["TABLE_NAME"].ToString();

                if (!sheetName.EndsWith("$"))
                    continue;

                // Get all rows from the Sheet
                cmd.CommandText = "SELECT * FROM [" + sheetName + "]";

                DataTable dt = new DataTable();
                dt.TableName = sheetName;

                OleDbDataAdapter da = new OleDbDataAdapter(cmd);
                da.Fill(dt);

                ds.Tables.Add(dt);
            }

            cmd = null;
            conn.Close();
        }

        workbook.AddWorksheet(ds);
return ds;