java判断两个时间相差得天数

Posted 2022-01-24 yang-xiansen

方法一：通过Calendar类得日期比较，在这需要考虑闰年和平年，也要考虑跨年份

/**
     * date2比date1多的天数
     * @param date1    
     * @param date2
     * @return    
     */
    public static int differentDays(Date date1,Date date2)
    
        Calendar cal1 = Calendar.getInstance();
        cal1.setTime(date1);
        
        Calendar cal2 = Calendar.getInstance();
        cal2.setTime(date2);
        int day1= cal1.get(Calendar.DAY_OF_YEAR);
        int day2 = cal2.get(Calendar.DAY_OF_YEAR);
        
        int year1 = cal1.get(Calendar.YEAR);
        int year2 = cal2.get(Calendar.YEAR);
        if(year1 != year2)   //不同一年
        
            int timeDistance = 0 ;
            for(int i = year1 ; i < year2 ; i ++)
            
                if(i%4==0 && i%100!=0 || i%400==0)    //闰年            
                
                    timeDistance += 366;
                
                else    //不是闰年
                
                    timeDistance += 365;
                
            
            
            return timeDistance + (day2-day1) ;
        
        else    //同一年
        
            System.out.println("判断day2 - day1 : " + (day2-day1));
            return day2-day1;
        
    

方法二：转化为毫秒数，再除以一天得毫秒数

/**
     * 通过时间秒毫秒数判断两个时间的间隔
     * @param date1
     * @param date2
     * @return
     */
    public static int differentDaysByMillisecond(Date date1,Date date2)
    
        int days = (int) ((date2.getTime() - date1.getTime()) / (1000*3600*24));
        return days;