java如何计算两个日期之间相差的天数

看完了jdk的help，发现sun没有提供这样的一个函数，朋友给了几个实现方法//取得剩余天数 SimpleDateFormat df=new SimpleDateFormat("yyyymmdd"); Date d0=new java.util.Date(); Date d1=df.parse(end_date); long time0=d0.getTime(); long time1=d1.getTime(); System.out.println((time1-time0)/(1000*60*60*24)); 这样算两个时间相差的天数比较好 /** * 计算两个日期之间相差的天数** @param date1 * @param date2* @return*/public static int diffdates(Date date1, Date date2) { int result = 0; ElapsedTime et = new ElapsedTime(); GregorianCalendar gc1 = new GregorianCalendar(); GregorianCalendar gc2 = new GregorianCalendar(); gc1.setTime(date1); gc2.setTime(date2); result = et.getDays(gc1, gc2); return result;}然后ElapseTime中的方法是： public int getDays(GregorianCalendar g1, GregorianCalendar g2) { int elapsed = 0; GregorianCalendar gc1, gc2; if (g2.after(g1)) { gc2 = (GregorianCalendar) g2.clone(); gc1 = (GregorianCalendar) g1.clone();} else {gc2 = (GregorianCalendar) g1.clone(); gc1 = (GregorianCalendar) g2.clone(); } gc1.clear(Calendar.MILLISECOND); gc1.clear(Calendar.SECOND); gc1.clear(Calendar.MINUTE); gc1.clear(Calendar.HOUR_OF_DAY); gc2.clear(Calendar.MILLISECOND); gc2.clear(Calendar.SECOND); gc2.clear(Calendar.MINUTE); gc2.clear(Calendar.HOUR_OF_DAY); while (gc1.before(gc2)) { gc1.add(Calendar.DATE, 1);elapsed++;}return elapsed;}其实使用joda最简单public boolean isRentalOverdue(DateTime datetimeRented) {