JAVA比较两个日期多的天数,(只考虑天数不考虑时间)

 /**
	 * 比较两个日期Date2比Date1(年月日)多的天数,(只考虑天数不考虑时间)
	 * 例如:2017-01-25 23:59:59与 2017-01-26 00:00:00   返回1
	 * 2017-01-25 与 2017-01-25   返回0
	 * 2017-01-28 与 2017-01-25   返回-3
	 * @author terry.peng
	 */
	public static int differDayQty(Date Date1,Date Date2){
		java.util.Calendar calendar = java.util.Calendar.getInstance();
		calendar.clear();
		calendar.setTime(Date1);
		int day1 = calendar.get(java.util.Calendar.DAY_OF_YEAR);
		int year1 = calendar.get(java.util.Calendar.YEAR);
		calendar.setTime(Date2);
		int day2 = calendar.get(java.util.Calendar.DAY_OF_YEAR);
		int year2 = calendar.get(java.util.Calendar.YEAR);
		if(year1 == year2){//同一年
			return day2-day1;
		}else if(year1<year2){//Date1<Date2
			int days = 0;
			for (int i = year1; i < year2; i++) {
				if(i%4 == 0 && i%100!=0 || i%400 == 0){//闰年
					days += 366;
				}else {
					days += 365;
				}
			}
			return days+(day2 - day1);
		}else{//Date1>Date2
			int days = 0;
			for (int i = year2; i < year1; i++) {
				if(i%4 == 0 && i%100!=0 || i%400 == 0){
					days += 366;
				}else {
					days += 365;
				}
			}
			return 0-days+(day2-day1);
		}
	}