Java时间戳转时间，获取一天的最大时间、最小时间，时间格式化

1. 时间格式化

   1.         //获取当前日期时间并按要求格式化，注意yyyyMMdd的大小写格式，大小写不一样，输出的结果也不一样
              SimpleDateFormat format1 = new SimpleDateFormat("yyyyMMdd");
              SimpleDateFormat format2 = new SimpleDateFormat("HHmmss");
              String date = format1.format(new Date());
              String time = format2.format(new Date());
              System.out.println("date:  "+ date +"   time:   "+ time);

       

2. 获取系统时间戳

   1. Long stamp1 = System.currentTimeMillis();//13位的时间戳，格式化后：2019-12-30 18:18:24.000
      Long stamp2 = System.currentTimeMillis()/1000;//10位的时间戳，格式化后：2019-12-30 18:18:24

       

3. 获取一天的最大时间、最小时间

   public static Long getDailyStartTime(Long timeStamp, String timeZone) {
           Calendar calendar = Calendar.getInstance();
           calendar.setTimeZone(TimeZone.getTimeZone(timeZone));
           calendar.setTimeInMillis(timeStamp);
           calendar.set(Calendar.HOUR_OF_DAY, 0);
           calendar.set(Calendar.SECOND, 0);
           calendar.set(Calendar.MINUTE, 0);
           calendar.set(Calendar.MILLISECOND, 0);
           return calendar.getTimeInMillis();
       }
   
       public static Long getDailyEndTime(Long timeStamp, String timeZone) {
           Calendar calendar = Calendar.getInstance();
           calendar.setTimeZone(TimeZone.getTimeZone(timeZone));
           calendar.setTimeInMillis(timeStamp);
           calendar.set(Calendar.HOUR_OF_DAY, 23);
           calendar.set(Calendar.MINUTE, 59);
           calendar.set(Calendar.SECOND, 59);
           calendar.set(Calendar.MILLISECOND, 999);
           return calendar.getTimeInMillis();
       }
   
   Long start = getDailyStartTime(System.currentTimeMillis(),"GMT+8:00");//一天的最早时间
   Long end = getDailyEndTime(System.currentTimeMillis(),"GMT+8:00");//一天的最晚时间