java可以使用计算日期的天数差，以下是详细代码：

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
public class test16 {
/**

• @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("2012-09-15 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)/(10003600*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)/(10003600*24);

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

}
// 转为毫秒相除