原文地址：https://www.yundashi168.com/396.html

输入：

System.out.println("时间差："+getDistanceTime("2016-05-01 12:00:00:000","2016-05-01 12:50:02:157"));

打印：（其它天，时，分都可以打印）

  /**
     * 统计两个时间的时间差
     * 相差几秒几毫秒
     */
    public static String getDistanceTime(String str1, String str2) {
        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss:SSS");
        Date one;
        Date two;
        long day = 0;//天数差
        long hour = 0;//小时数差
        long min = 0;//分钟数差
        long second=0;//秒数差
        long diff=0 ;//毫秒差
        String result = null;
        try {
            final Calendar c = Calendar.getInstance();
            c.setTimeZone(TimeZone.getTimeZone("GMT+8:00"));
            one = df.parse(str1);
            c.setTime(one);
            two = df.parse(str2);
            long time1 = one.getTime();
            long time2 = two.getTime();
            diff = time2 - time1;
            day = diff / (24 * 60 * 60 * 1000);
            hour = (diff / (60 * 60 * 1000) - day * 24);
            min = ((diff / (60 * 1000)) - day * 24 * 60 - hour * 60);
            second = diff/1000;
            System.out.println("day="+day+" hour="+hour+" min="+min+" ss="+second%60+" SSS="+diff%1000);
            result=second%60+"秒"+diff%1000+"毫秒";
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return result;
    }

计算两个日期之间的天数:

  public static void main(String[] args) throws ParseException {
        String startTime = "2019-11-30";
        String endTime = "2019-12-12";
        Calendar startCal = Calendar.getInstance();
        Calendar endCal = Calendar.getInstance();
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        Date startDate =  sdf.parse(startTime);
        Date endDate = sdf.parse(endTime);
        startCal.setTime(startDate);
        endCal.setTime(endDate);
        List<String> list = new ArrayList<>();
        //得到两个日期相差的天数   还可通过去除后面的数 求得相差的小时数,分钟数,秒   等等
         int days = ((int)(endCal.getTime().getTime()/1000)-(int)(startCal.getTime().getTime()/1000))/3600/24;   
         for(int i = 0;i<=days;i++){
             list.add(sdf.format(startCal.getTime()));
             startCal.add(Calendar.DAY_OF_MONTH, 1);
         } 
         System.out.println(days);
         System.out.println(list);
    }

/**
* startTime  起始日期
* endTime   截止日期
* dateType  日期类型 HOUR/DAY/MONTH/YEAR    
*/
public Integer dateTimeNums(String startTime,String endTime,String dateType) throws ParseException{
        String fmtStr = null;
        int timeNum = 3600 * 24;
        switch(dateType){
            case "HOUR" : 
                fmtStr = "yyyy-MM-dd HH"; 
                timeNum = 3600;
                break;
            case "DAY" :
                fmtStr = "yyyy-MM-dd";
                timeNum = 3600 * 24 ;
                break;
            case "MONTH" :
                fmtStr = "yyyy-MM";
                timeNum = 3600 * 24 * 30;
                break;
            case "YEAR" :
                fmtStr = "yyyy";
                timeNum = 3600 * 24 * 365 ;
                break;
            default :
                fmtStr = "yyyy-MM-dd";
                break;
        } 
        
        Calendar startCal = Calendar.getInstance();
        Calendar endCal = Calendar.getInstance();
        SimpleDateFormat sdf = new SimpleDateFormat(fmtStr);//此处修改日期格式
        Date startDate =  sdf.parse(startTime);
        Date endDate = sdf.parse(endTime);
        startCal.setTime(startDate);
        endCal.setTime(endDate);
        startCal.compareTo(endCal);
      //得到两个日期相差的天数   
        int nums = ((int)(endCal.getTime().getTime()/1000)-(int)(startCal.getTime().getTime()/1000))/timeNum;//此处修改日期单位   
        return nums;
    }

JS计算两个日期时间差，天 小时 分 秒格式

　　用法：

var diffTimeShow = diffTime('2017-03-02 09:10','2017-03-17 04:10');

1. var st1 = "2008-8-1 8:50:01";  
2. var st2 = "2008-8-3 8:50:01";  
3. var time1 = new Date(st1);                                //创建时间1  
4. var tiem2 = new Date(st2);                                //创建时间2  
5. /* 
6. *如果求的时间差为天数则处以864000000，如果是小时数则在这个数字上 
7. *除以24，分钟数则再除以60，依此类推 
8. */  
9. var days = (time1.getTime() - time2.getTime()) / 86400000;  
10. alert(days); 

或者 用另一个方法：

　　原文链接：http://caibaojian.com/javascript-getdatadiff.html

使用的方法很简单，比如计算天数可以这样：·

GetDateDiff("2010-02-26 16:00:00", "2011-07-02 21:48:40", "day");