public void getDate(){
//获取前几天日期
Calendar calendar = Calendar.getInstance();
SimpleDateFormat simpleDateFormat =new SimpleDateFormat("yyyy-MM-dd");
calendar.setTime(new Date());
//三天前
calendar.set(Calendar.DATE,calendar.get(Calendar.DATE)-3);
//三天前零点
String thirdDate = simpleDateFormat.format(calendar.getTime()) +" " +"00:00:00";
//获取上一个月第一天日期
Calendar calendar1 = Calendar.getInstance();
//上个月
calendar1.add(Calendar.MONTH,-1);
//该月第一天
calendar1.set(Calendar.DAY_OF_MONTH,1);
//上个月第一天日期23点59分59秒
String lastMonthFirstDay = simpleDateFormat.format(calendar1.getTime()) +" " +"23:59:59";
//获取上个月最后一天日期
Calendar calendar2=Calendar.getInstance();
int month=calendar2.get(Calendar.MONTH);
calendar2.set(Calendar.MONTH, month-1);
calendar2.set(Calendar.DAY_OF_MONTH, calendar2.getActualMaximum(Calendar.DAY_OF_MONTH));
String lastMonthEndDay = simpleDateFormat.format(calendar2.getTime()) +" " +"23:59:59";
System.out.println("三天前零点："+thirdDate);
System.out.println("上一个月第一天日期："+lastMonthFirstDay);
System.out.println("上个月最后一天日期："+lastMonthEndDay);
}
