用 easy poi 导出 excel 的时候，\n被吃掉了
解决方法
Workbook workbook = ExcelExportUtil.exportExcel(params, map);
CellStyle cs = workbook.createCellStyle();
cs.setWrapText(true);
for (int i = workbook.getSheetAt(0).getFirstRowNum() + 2; i <= workbook.getSheetAt(0).getLastRowNum(); i++) {
Row row = workbook.getSheetAt(0).getRow(i);
row.getCell(3).setCellStyle(cs);
}