java 利用poi 实现excel合并单元格后出现边框有的消失的解决方法

/**
* 合并单元格后出现边框有的消失的解决方法
* @param borderStyle
* @param region
* @param sheet
*/
public static void setBorderStyle(BorderStyle borderStyle, CellRangeAddress region, XSSFSheet sheet){
RegionUtil.setBorderBottom(borderStyle, region, sheet); //下边框
RegionUtil.setBorderLeft(borderStyle, region, sheet); //左边框
RegionUtil.setBorderRight(borderStyle, region, sheet); //右边框
RegionUtil.setBorderTop(borderStyle, region, sheet); //上边框
}