POI操作

HSSFWorkbook workbook = new HSSFWorkbook();
Sheet sheet = workbook.createSheet();
sheet.setColumnWidth(0, 10 * 256);
sheet.setColumnWidth(1, 15 * 256);
sheet.setColumnWidth(2, 40 * 256);
sheet.setColumnWidth(3, 40 * 256);

CellRangeAddress region = new CellRangeAddress(0, 0, 1, 2); //起始行，结束行，起始列，结束列
sheet.addMergedRegion(region);

CellStyle cellStyle = workbook.createCellStyle();
cellStyle.setAlignment(HSSFCellStyle.ALIGN_CENTER);
cell.setCellStyle(cellStyle);

//1、内容加上换行符"\n"
//2、单元格加上换行格式
HSSFWorkbook workbook = new HSSFWorkbook();
Sheet sheet = workbook.createSheet();
HSSFCellStyle cs = workbook.createCellStyle(); // 换行的关键，自定义单元格内容换行规则
cs.setWrapText(true);
cell6.setCellStyle(cs);