java中处理日期 日期向前推 日期向后 推

1. /**
2.      * 向前 后 推算时间 正负都可以
3.      * @param days
4.      * @return
5.      */
6.     public static String timeUtil(int days){
7.         SimpleDateFormat sd = new SimpleDateFormat("yyyy-MM-dd");
8.         Calendar calendar = Calendar.getInstance();
9.         int i = calendar.get(Calendar.DAY_OF_YEAR);
10.         i=i+days;
11.         calendar.set(Calendar.DAY_OF_YEAR, i);
12.         return sd.format(calendar.getTime());
13.     }