Calendar的DAY_OF_MONTH, DAY_OF_YEAR, DATE的区别
From: https://blog.csdn.net/weixin_34233679/article/details/87286628cal1.add(Calendar.DAY_OF_MONTH,1); cal1.add(Calendar.DAY_OF_YEAR,1); cal1.add(Calendar.DATE,1);就单纯的add操作结果都一样，因为都是将日期+1就没有区...
