Date型时间获取date所属的每周第一天,每月第一天,每季第一天,每年第一天
/**
* 获取date所属月的第一天
*
* @param date
* @return
* @throws ParseException
*/
private Date getFirstDayMonth(Date date) {
Calendar calendar = Calendar.getInstance();
calendar.setTime(date);
calendar.set(Calendar.DAY_OF_MONTH, calendar.getActualMinimum(Calendar.DAY_OF_MONTH));
Date firstDay = calendar.getTime();
return firstDay;
}
/**
* 获取date所属年的第一天
*
* @param date
* @return
* @throws ParseException
*/
private Date getFirstDayYear(Date date) {
Calendar calendar = Calendar.getInstance();
calendar.setTime(date);
calendar.set(Calendar.DAY_OF_YEAR, calendar.getActualMinimum(Calendar.DAY_OF_YEAR));
Date firstDay = calendar.getTime();
return firstDay;
}
/**
* 获取date所属季的第一天
*
* @param date
* @return
* @throws ParseException
*/
private Date getFirstDaySeason(Date date) throws ParseException {
Calendar calendar = Calendar.getInstance();
calendar.setTime(date);
int year = calendar.get(Calendar.YEAR);
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
Date january = sdf.parse(year + "-01-01");
Date april = sdf.parse(year + "-04-01");
Date july = sdf.parse(year + "-07-01");
Date october = sdf.parse(year + "-10-01");
if (date.compareTo(april) < 0) {
return january;
} else if (date.compareTo(july) < 0) {
return april;
} else if (date.compareTo(october) < 0) {
return july;
} else {
return october;
}
}
/**
* 获取date所属周的第一天
*
* @param date
* @return
*/
private Date getFirstDayWeek(Date time) {
Calendar cal = Calendar.getInstance();
cal.setTime(time);
// 判断要计算的日期是否是周日,如果是则减一天计算周六的,否则会出问题,计算到下一周去了
int dayWeek = cal.get(Calendar.DAY_OF_WEEK);// 获得当前日期是一个星期的第几天
if (1 == dayWeek) {
cal.add(Calendar.DAY_OF_MONTH, -1);
}
cal.setFirstDayOfWeek(Calendar.MONDAY);// 设置一个星期的第一天,按中国的习惯一个星期的第一天是星期一
int day = cal.get(Calendar.DAY_OF_WEEK);// 获得当前日期是一个星期的第几天
cal.add(Calendar.DATE, cal.getFirstDayOfWeek() - day);// 根据日历的规则,给当前日期减去星期几与一个星期第一天的差值
return cal.getTime();
}