java计算两个日期之间相差的天数

/**

*日期格式的计算

*/ 

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));    

    }