@Override
    public CellStyle getCellStyleAt(int idx) {
        if (idx < 0 || idx >= csvCellStyleList.size()) {
            return null;
        }
        return csvCellStyleList.get(idx);
    }
Set the encoding prefix in the csv file, otherwise the office may open garbled characters.
Default true.
fastexcel-core/src/main/java/cn/idev/excel/metadata/csv/CsvWorkbook.java