java 计算时间差

DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    try
    {
      Date d1 = df.parse("2004-03-26 13:31:40");
      Date d2 = df.parse("2004-01-02 11:30:24");
      long diff = d1.getTime() - d2.getTime();//这样得到的差值是微秒级别
      long days = diff / (1000 * 60 * 60 * 24);

      long hours = (diff-days*(1000 * 60 * 60 * 24))/(1000* 60 * 60);
      long minutes = (diff-days*(1000 * 60 * 60 * 24)-hours*(1000* 60 * 60))/(1000* 60);
      System.out.println(""+days+"天"+hours+"小时"+minutes+"分");
    }catch (Exception e)
    {
    }