cal.get(Calendar.YEAR);
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyyMMdd");
String date=simpleDateFormat.format(new Date());
String y=date.substring(0,4);
String m=date.substring(4,6);
String d=date.substring(6,8);
原文：http://blog.csdn.net/vipyhd/article/details/39551653