SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

Calendar c = Calendar.getInstance();

1.过去七天

c.setTime(new Date());

c.add(Calendar.DATE, - 7);

Date d = c.getTime();

String day = format.format(d);

System.out.println("过去七天："+day);

2.过去一月

c.setTime(new Date());

c.add(Calendar.MONTH, -1);

Date m = c.getTime();

String mon = format.format(m);

System.out.println("过去一个月："+mon);

3.过去三个月

c.setTime(new Date());

c.add(Calendar.MONTH, -3);

Date m3 = c.getTime();

String mon3 = format.format(m3);

System.out.println("过去三个月："+mon3);

4.过去一年

c.setTime(new Date());

c.add(Calendar.YEAR, -1);

Date y = c.getTime();

String year = format.format(y);

System.out.println("过去一年："+year);

5.现在时间24小时制

SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

String nowDate=format.format(new Date());

System.out.println(nowDate);

6.当天的开始时间

SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");

Calendar c = Calendar.getInstance();

String start = format.format(c.getTime())+" 00:00:00";

System.out.println(start);

7.当天的截止时间

SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");

Calendar calendar = Calendar.getInstance();

String end = format.format(calendar.getTime())+" 23:59:59";

System.out.println(end);

8.当前时间的前一个星期 开始时间

SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");

Calendar c = Calendar.getInstance();

c.add(Calendar.DAY_OF_MONTH, -6);

String start = format.format(c.getTime())+" 00:00:00";

System.out.println(start);

9.当天日期前一个月

SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");

Calendar c = Calendar.getInstance();

c.add(Calendar.MONTH, -1);    //得到前一个月

String start = format.format(c.getTime())+" 00:00:00";

System.out.println(start);

10.当前时间的前一年开始时间

SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");

Calendar c = Calendar.getInstance();

c.add(Calendar.YEAR, -1); //年份减1

String start =format.format(c.getTime())+" 00:00:00";

System.out.println(start);

11.当前时间的周一时间和周末时间 setfirstdayofweek()方法

SimpleDateFormat format  = new SimpleDateFormat("YYYY-MM-dd ");

Calendar c = Calendar.getInstance();

c.set(Calendar.DAY_OF_WEEK,Calendar.MONDAY);

String weekStart = format.format(c.getTime())+" 00:00:00";

System.out.println(weekStart);

Calendar ca = Calendar.getInstance();

ca.setFirstDayOfWeek(Calendar.MONDAY);

ca.set(Calendar.DAY_OF_WEEK, ca.getFirstDayOfWeek() + 6); // Sunday

String weekEnd = format.format(ca.getTime())+" 23:59:59";

System.out.println(weekEnd);

12.当前时所在月份的第一天和最后一天

SimpleDateFormat format=new SimpleDateFormat("yyyy-MM-dd");

Calendar c = Calendar.getInstance();

c.set(Calendar.DAY_OF_MONTH,1);//设置为1号,当前日期既为本月第一天

String monthStart = format.format(c.getTime())+" 00:00:00";

System.out.println(monthStart);

Calendar ca = Calendar.getInstance();

ca.set(Calendar.DAY_OF_MONTH, ca.getActualMaximum(Calendar.DAY_OF_MONTH));

String monthEnd = format.format(ca.getTime())+" 23:59:59";

System.out.println(monthEnd);

13.当期时间所在年份的开始时间

SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");

Calendar c = Calendar.getInstance();

c.set(c.get(Calendar.YEAR) ,0, 1);//开始时间日期

String yearStart = format.format(c.getTime())+" 00:00:00";

System.out.println(yearStart);

Calendar ca = Calendar.getInstance();

ca.set(ca.get(Calendar.YEAR) ,11, ca.getActualMaximum(Calendar.DAY_OF_MONTH));//结束日期

String yearEnd = format.format(ca.getTime())+" 23:59:59";

System.out.println(yearEnd);

14.计算时间差取得两个时间的微秒级的时间差

//得微秒级时间差

long val = calendarEnd.getTimeInMillis() - calendarBegin.getTimeInMillis();

//换算后得到天数

long day = val / (1000 * 60 * 60 * 24);

15.获取某个时间的上周一和周日

Calendar cal = Calendar.getInstance();

//n为推迟的周数，1本周，-1向前推迟一周，2下周，依次类推

int n = 1;

String monday;

cal.add(Calendar.DATE, n*7);

//想周几，这里就传几Calendar.MONDAY(TUESDAY...)

cal.set(Calendar.DAY_OF_WEEK,Calendar.MONDAY);

monday = new SimpleDateFormat("yyyy-MM-dd").format(cal.getTime());

System.out.println(monday);