Java判断两个日期相差天数的方法

import java.util.Calendar;
public class DateDifferent{
 public static void main(String[] args){
 Calendar calendar1 = Calendar.getInstance();
 Calendar calendar2 = Calendar.getInstance();
 calendar1.set(2007, 01, 10);
 calendar2.set(2007, 07, 01);
 long milliseconds1 = calendar1.getTimeInMillis();
 long milliseconds2 = calendar2.getTimeInMillis();
 long diff = milliseconds2 - milliseconds1;
 long diffSeconds = diff / 1000;
 long diffMinutes = diff / (60 * 1000);
 long diffHours = diff / (60 * 60 * 1000);
 long diffDays = diff / (24 * 60 * 60 * 1000);
 System.out.println("\nThe Date Different Example");
 System.out.println("Time in milliseconds: " + diff + " milliseconds.");
 System.out.println("Time in seconds: " + diffSeconds + " seconds.");
 System.out.println("Time in minutes: " + diffMinutes + " minutes.");
 System.out.println("Time in hours: " + diffHours + " hours.");
 System.out.println("Time in days: " + diffDays + " days.");
 }
}

/**
 * 得到两个日期相差的天数
 */
public static int getBetweenDay(Date date1, Date date2) {
  Calendar d1 = new GregorianCalendar();
  d1.setTime(date1);
  Calendar d2 = new GregorianCalendar();
  d2.setTime(date2);
  int days = d2.get(Calendar.DAY_OF_YEAR)- d1.get(Calendar.DAY_OF_YEAR);
  System.out.println("days="+days);
  int y2 = d2.get(Calendar.YEAR);
  if (d1.get(Calendar.YEAR) != y2) {
//      d1 = (Calendar) d1.clone();
    do {
      days += d1.getActualMaximum(Calendar.DAY_OF_YEAR);
      d1.add(Calendar.YEAR, 1);
    } while (d1.get(Calendar.YEAR) != y2);
  }
  return days;
}