【EXCEL导出】适应宽度

Field[] fields = cls.getDeclaredFields();//获取类下字段
        int maxColumn = fields.length;

for (int i = 0; i <= maxColumn; i++)
        {
            sheet.autoSizeColumn(i);
        }
        //获取当前列的宽度，然后对比本列的长度，取最大值
        for (int columnNum = 0; columnNum <= maxColumn; columnNum++)
        {
            int columnWidth = sheet.getColumnWidth(columnNum) / 256;
            for (int rowNum = 0; rowNum <= sheet.getLastRowNum(); rowNum++)
            {
                Row currentRow;
                //当前行未被使用过
                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 * 256);
        }