poi 合并单元格后添加边框

Region region = new Region(3,(short)(0),3,(short)(2));
sheet.addMergedRegion(region);
setRegionStyle(region); //在执行此行之后，如果重新创建合并了的单元格，会覆盖掉此处定义的样式。建议把此行代码放到最后面。

protected void setRegionStyle(Region region) {

        for (int i = region.getRowFrom(); i <= region.getRowTo(); i ++) {
            HSSFRow row = HSSFCellUtil.getRow(i, sheet);
            for (int j = region.getColumnFrom(); j <= region.getColumnTo(); j++) {
                HSSFCell cell = HSSFCellUtil.getCell(row, (short)j);
                cell.setCellStyle(getContentStyle());//getContentStyle()为自己定义的样式
            }
        }

    }