Calculator.java

package com.diandi.demo.util;

/**
 * *******************************************************************************
 * *********    Author : klob(kloblic@gmail.com) .
 * *********    Date : 2014-11-29  .
 * *********    Time : 11:46 .
 * *********    Project name : Diandi1.18 .
 * *********    Version : 1.0
 * *********    Copyright @ 2014, klob, All Rights Reserved
 * *******************************************************************************
 */

import java.util.Calendar;
import java.util.Date;

public class Calculator {
    private final static String start_day = TimeUtil.getDatetimeString();
    ;

    public Calculator() {
    }

    public static String calculate(String year, String month, String day) {
        int startYear, startMonth, startDay, endYear, endMonth, endDay;
        startYear = Integer.valueOf(start_day.substring(0, 4));
        startMonth = Integer.valueOf(start_day.substring(5, 7));
        startDay = Integer.valueOf(start_day.substring(8, 10));


        endYear = Integer.valueOf(year);
        endMonth = Integer.valueOf(month);
        endDay = Integer.valueOf(day);
        Date startdate = new Date(startYear, startMonth, startDay);
        Date enddate = new Date(endYear, endMonth, endDay);
        return String.valueOf(daysBetween(startdate, enddate));
    }

    public static int calculate(String end_day) {
        int startYear, startMonth, startDay, endYear, endMonth, endDay;
        startYear = Integer.valueOf(start_day.substring(0, 4));
        startMonth = Integer.valueOf(start_day.substring(5, 7));
        startDay = Integer.valueOf(start_day.substring(8, 10));


        endYear = Integer.valueOf(end_day.substring(0, 4));
        endMonth = Integer.valueOf(end_day.substring(5, 7));
        endDay = Integer.valueOf(end_day.substring(8, 10));
        Date startdate = new Date(startYear, startMonth, startDay);
        Date enddate = new Date(endYear, endMonth, endDay);
        return daysBetween(startdate, enddate);
    }

    public static int daysBetween(Date dateFrom, Date dateEnd) {
        Calendar cal = Calendar.getInstance();
        cal.setTime(dateFrom);
        long time1 = cal.getTimeInMillis();
        cal.setTime(dateEnd);
        long time2 = cal.getTimeInMillis();
        long between_days = (time2 - time1) / (1000 * 3600 * 24);
        int m = Integer.parseInt(String.valueOf(between_days));
        return m;
    }

}