计算两日期相差几天

public static long getDaySub(String beginDateStr, String endDateStr,String formartType) {
  long day = 0;
  java.text.SimpleDateFormat format = new java.text.SimpleDateFormat(formartType);
  java.util.Date beginDate;
  java.util.Date endDate;
  try {
   beginDate = format.parse(beginDateStr);
   endDate = format.parse(endDateStr);
   day = (endDate.getTime() - beginDate.getTime()) / (24 * 60 * 60 * 1000);
   // System.out.println("相隔的天数="+day);
  } catch (Exception e) {
   // TODO 自动生成 catch 块
   e.printStackTrace();
  }
  return day;
 }