JAVA添加或者减少日期并且忽略周六日

/**
     * 忽略周六日添加或者减少指定天数
     * @param date  任意日期
     * @param amount 为正数则累加，为负数则递减
     */
    public static Date addOrSubDaysIgnoreWeekends(Date date,int amount){
        Calendar cal = Calendar.getInstance();
        cal.setTime(date);
        int week = cal.get(Calendar.DAY_OF_WEEK) - 1;
        if(amount>=0){
            if(week==6){
                amount=amount + ((amount - 1) / 5) * 2 + 1;
            }else{
                amount=amount + (((week + amount) - 1) / 5) * 2;
            }
        }else{
            if(week==0){
                amount=amount - ((-amount - 1) / 5) * 2 - 1;
            }else{
                amount=amount - ((-(amount + week) + 5) / 5) * 2;
            }
        }
        cal.add(Calendar.HOUR, amount * 24);
        return cal.getTime();
    }