java poi 導出excel自適應列寬

public static void setAutoColumnWidth(HSSFSheet sheet,int maxColumnNum) {
        try{
            //獲取當前列的寬度，然后對比本列的長度，取最大值
            for (int columnNum = 0; columnNum <= maxColumnNum; columnNum++)
            {
                int columnWidth = sheet.getColumnWidth(columnNum) / 256;
                for (int rowNum = 0; rowNum <= sheet.getLastRowNum(); rowNum++)
                {
                    Row currentRow;
                    //當前行未被使用過
                    if (sheet.getRow(rowNum) == null)
                    {
                        currentRow = sheet.createRow(rowNum);
                    }
                    else
                    {
                        currentRow = sheet.getRow(rowNum);
                    }

                    if(currentRow.getCell(columnNum) != null)
                    {
                        Cell currentCell = currentRow.getCell(columnNum);
                        int length = currentCell.toString().getBytes("GBK").length;
                        if (columnWidth < length + 1)
                        {
                            columnWidth = length + 1;
                        }
                    }
                }
                sheet.setColumnWidth(columnNum, columnWidth * 300);
            }
        }catch (Exception e){
            e.printStackTrace();
        }
    }