function mdate($time = NULL) {
        $text = '';
        $time = $time === NULL || $time > time() ? time() : intval($time);
        $t = time() - $time; //時間差 （秒）
        
        $y = date('Y', $time)-date('Y', time());//是否跨年
        switch($t){
            case $t == 0:
                $text = '剛剛';
            break;
            case $t < 60:
                $text = $t . '秒前'; // 一分鐘內
            break;
            case $t < 60 * 60:
                $text = floor($t / 60) . '分鐘前'; //一小時內
            break;
            case $t < 60 * 60 * 24:
                $text = floor($t / (60 * 60)) . '小時前'; // 一天內
            break;
            case $t < 60 * 60 * 24 * 3:
                $text = floor($time/(60*60*24)) ==1 ?'昨天 ' . date('H:i', $time) : '前天 ' . date('H:i', $time) ; //昨天和前天
            break;
            case $t < 60 * 60 * 24 * 30:
                $text = date('m月d日 H:i', $time); //一個月內
            break;
            case $t < 60 * 60 * 24 * 365&&$y==0:
                $text = date('m月d日', $time); //一年內
            break;
            default:
                $text = date('Y年m月d日', $time); //一年以前
            break;
        }
            
        return $text;
    }