Calendar日历

Calendar calendar=Calendar.getInstance();
//上一年的今天
calendar.add(Calendar.YEAR,-1);
System.out.println(calendar.getTime());
//上一年上一月
calendar.add(Calendar.MONTH,-1);
System.out.println(calendar.getTime());
//上一年上一月的上一周
calendar.add(Calendar.DATE,-7);
System.out.println(calendar.getTime());