工作中用到的小算法，计算两日期间隔xx年xx月xx天

package test;

import java.util.Calendar;

public class Test {
	static int year = 0;
	static int month = 0;
	static int day = 0;

	public static void main(String[] args) {

		Calendar start = Calendar.getInstance();
		start.set(2015, 1, 5, 0, 0, 0);

		Calendar end = Calendar.getInstance();
		end.set(2039, 4, 3, 0, 0, 0);

		start.add(Calendar.MONTH, 1);
		Calendar nextMonth = Calendar.getInstance();
		nextMonth.setTime(start.getTime());
		start.add(Calendar.MONTH, -1);

		start.add(Calendar.YEAR, 1);
		Calendar nextYear = Calendar.getInstance();
		nextYear.setTime(start.getTime());
		start.add(Calendar.YEAR, -1);

		Calendar today = Calendar.getInstance();
		Calendar yestoday = Calendar.getInstance();
		today.setTime(start.getTime());

		while (true) {
			boolean spanYear = false;
			boolean spanMonth = false;

			yestoday.setTime(today.getTime());

			today.add(Calendar.DAY_OF_YEAR, 1);

			spanYear = today.getTime().getTime() >= nextYear.getTime().getTime();
			spanMonth = today.getTime().getTime() >= nextMonth.getTime().getTime();

			if (spanYear) {
				year++;
				month = 0;
				day = 0;
				nextYear.add(Calendar.YEAR, 1);
				nextMonth.add(Calendar.MONTH, 1);
			 
			} else if (spanMonth) {
				month++;
				day = 0;
				nextMonth.add(Calendar.MONTH, 1);
				 
			} else {
				day++;
			}

			if (today.get(Calendar.YEAR) == end.get(Calendar.YEAR)
					&& today.get(Calendar.MONTH) == end.get(Calendar.MONTH)
					&& today.get(Calendar.DAY_OF_MONTH) == end.get(Calendar.DAY_OF_MONTH))
				break;
		}

		System.out.println((year < 1 ? "" : year + "年") + (month < 1 ? "" : month + "月") + (day < 1 ? "" : day + "天"));

	}

}