计算两个日期的天数间隔

import java.text.ParseException;   import java.text.SimpleDateFormat;   import java.util.Calendar;   import java.util.Date;       public class DateTest {             public static void main(String[] args) {                  SimpleDateFormat sf=new SimpleDateFormat("yyyyMMdd");        try {           Date date=sf.parse("20090125");            Calendar cl=Calendar.getInstance();             cl.setTime(date);             int year1=cl.get(Calendar.YEAR);            int day1= cl.get(Calendar.DAY_OF_YEAR );            Date date2= sf.parse("20110725");             Calendar c2=Calendar.getInstance();          c2.setTime(date);              int year2=c2.get(Calendar.YEAR);            int day2= c2.get(Calendar.DAY_OF_YEAR);            System.out.println((year2-year1)*365+(day2-day1));       } catch (ParseException e) {           // TODO Auto-generated catch block           e.printStackTrace();       }                  }     }  

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?? 计算任意两个日期的天数差，一次类推，年、月、时、分、秒也可以的

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