code: private void mergeRows(Sheet sheet,CellStyle cellStyle,ExcelMeta excelMeta) {
      	
      	Row row = null;
      	Cell cell = null;
      	String[] lastRowVals = new String[excelMeta.getTitleColumnNum()];
      	for (int r = 0; r < excelMeta.getTitleRowNum(); r++) {
  			for (int c = 0; c < excelMeta.getTitleColumnNum(); c++) {
  				row = sheet.getRow(r);
                  cell = row.getCell(c);
                  if(r == 0){
                  	lastRowVals[c] = cell.getStringCellValue();
                  }else{                	
                  	if(StringUtils.equals(lastRowVals[c],cell.getStringCellValue())){
                  		cell.setCellValue("");
                  		sheet.addMergedRegion(new CellRangeAddress(0, r, c, c));
                  		Cell nowCell = sheet.getRow(0).getCell(c);
                  		nowCell.setCellStyle(cellStyle);
                  	}
                  }
                  
  			}
  		}
      
      }
docs: TODO 暂时支持两行表头