java 计算两个字符串,或者Date相差的天数

package com.glmedia.advert.utils;

import java.text.ParseException;

import java.text.SimpleDateFormat;

import java.util.Calendar;

import java.util.Date;

public class DateTimeUtil3 {

/**

* @param args

* @throws ParseException

*/

public static void main(String[] args) throws ParseException {

// TODO Auto-generated method stub

SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

Date d1=sdf.parse("2012-09-08 10:10:10");

Date d2=sdf.parse("2016-09-15 00:00:00");

System.out.println(daysBetween(d1,d2));

System.out.println(daysBetween("2012-09-08 10:10:10","2012-09-15 00:00:00"));

}

/**

* 计算两个日期之间相差的天数

* @param smdate 较小的时间

* @param bdate 较大的时间

* @return 相差天数

* @throws ParseException

*/

public static int daysBetween(Date smdate,Date bdate) throws ParseException

{

SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");

smdate=sdf.parse(sdf.format(smdate));

bdate=sdf.parse(sdf.format(bdate));

Calendar cal = Calendar.getInstance();

cal.setTime(smdate);

long time1 = cal.getTimeInMillis();

cal.setTime(bdate);

long time2 = cal.getTimeInMillis();

long between_days=(time2-time1)/(1000*3600*24);

return Integer.parseInt(String.valueOf(between_days));

}

/**

*字符串的日期格式的计算

*/

public static int daysBetween(String smdate,String bdate) throws ParseException{

SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");

Calendar cal = Calendar.getInstance();

cal.setTime(sdf.parse(smdate));

long time1 = cal.getTimeInMillis();

cal.setTime(sdf.parse(bdate));

long time2 = cal.getTimeInMillis();

long between_days=(time2-time1)/(1000*3600*24);

return Integer.parseInt(String.valueOf(between_days));

}

}