Calendar calendar = Calendar.getInstance();
System.out.println(calendar.get(Calendar.DAY_OF_YEAR)); //1
System.out.println(calendar.get(Calendar.DAY_OF_MONTH)); //2
System.out.println(calendar.get(Calendar.DAY_OF_WEEK)); //3
System.out.println(calendar.get(Calendar.DAY_OF_WEEK_IN_MONTH)); //4
System.out.println(calendar.get(Calendar.DAY_OF_YEAR)); //1
System.out.println(calendar.get(Calendar.DAY_OF_MONTH)); //2
System.out.println(calendar.get(Calendar.DAY_OF_WEEK)); //3
System.out.println(calendar.get(Calendar.DAY_OF_WEEK_IN_MONTH)); //4
System.out.println(calendar.get(Calendar.WEEK_OF_MONTH)); //5
1、DAY_OF_YEAR：当年第几天，从1开始算
2、DAY_OF_MONTH：当月第几天，从1开始算
3、DAY_OF_WEEK：本周第几天，1是星期天，2是星期一
4、DAY_OF_WEEK_IN_MONTH：某月中第几周，按这个月1号算，1号起就是第1周，8号起就是第2周，以月份天数为标准
5、WEEK_OF_MONTH：日历式的第几周