Java中根据生日和当前时间计算年龄的简单做法

SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
        long shengRi = simpleDateFormat.parse(birthday).getTime();
        long time = System.currentTimeMillis();
        //当前时间和生日的差值
        long cha = time - shengRi;
        long age = cha / (365L * 24 * 3600 * 1000);