HSSFCellStyle style = hwb.createCellStyle();
设置边框颜色(上下左右线条设置为黑色)
style.setTopBorderColor(HSSFColor.BLACK.index);
style.setBottomBorderColor(HSSFColor.BLACK.index);
style.setLeftBorderColor(HSSFColor.BLACK.index);
style.setRightBorderColor(HSSFColor.BLACK.index);
引用:https://zhidao.baidu.com/question/525827372.html