带缓存数据功能的mysqli类

<?php
/**
 * Mysqli类
 *
 * @author 废墟
 * @version v1.0 2009-08-18
 * @link http://anerg.cn/
 */
class db_mysqli {
    protected $mysqli;
    protected $sql;
    protected $rs;
    protected $query_num    = 0;
    protected $fetch_mode    = MYSQLI_ASSOC;
    protected $cache_dir    = './cache/';
    protected $cache_time    = 1800;

    public function  __construct($dbhost, $dbuser, $dbpass, $dbname) {
        $this->mysqli    = new mysqli($dbhost, $dbuser, $dbpass, $dbname);
        if(mysqli_connect_errno()) {
            $this->mysqli    = false;
            echo '<h2>'.mysqli_connect_error().'</h2>';
            die();
        } else {
            $this->mysqli->set_charset("utf8");
        }
    }
    public function  __destruct() {
        $this->free();
        $this->close();
    }
    protected function free() {
        @$this->rs->free();
    }
    protected function close() {
        $this->mysqli->close();
    }
    protected function fetch() {
        return $this->rs->fetch_array($this->fetch_mode);
    }
    protected function getQuerySql($sql, $limit = null) {
        if (@preg_match("/[0-9]+(,[ ]?[0-9]+)?/is", $limit) && !preg_match("/ LIMIT [0-9]+(,[ ]?[0-9]+)?$/is", $sql)) {
            $sql .= " LIMIT " . $limit;
        }
        return $sql;
    }
    protected function get_cache($sql,$method) {
        include_once './cache.php';//若框架中使用__autoload()，这里可以不用加载文件
        $cache    = new cache($this->cache_dir,$this->cache_time);
        $cache_file    = md5($sql.$method);
        $res    = $cache->get_cache($cache_file);
        if(!$res) {
            $res    = $this->$method($sql);
            $cache->set_cache($cache_file, $res);
        }
        return $res;
    }
    public function query_num() {
        return $this->query_num;
    }
    public function set_cache_dir($cache_dir) {
        $this->cache_dir    = $cache_dir;
    }
    public function set_cache_time($cache_time) {
        $this->cache_time    = $cache_time;
    }
    public function query($sql, $limit = null) {
        $sql    = $this->getQuerySql($sql, $limit);
        $this->sql    = $sql;
        $this->rs    = $this->mysqli->query($sql);
        if (!$this->rs) {
            echo "<h2>".$this->mysqli->error."</h2>";
            die();
        } else {
            $this->query_num++;
            return $this->rs;
        }
    }
    public function getOne($sql) {
        $this->query($sql, 1);
        $this->fetch_mode    = MYSQLI_NUM;
        $row = $this->fetch();
        $this->free();
        return $row[0];
    }
    public function get_one($sql) { return $this->getOne($sql); }
    public function cache_one($sql) {
        $sql    = $this->getQuerySql($sql, 1);
        return $this->get_cache($sql, 'getOne');
    }
    public function getRow($sql, $fetch_mode = MYSQLI_ASSOC) {
        $this->query($sql, 1);
        $this->fetch_mode    = $fetch_mode;
        $row = $this->fetch();
        $this->free();
        return $row;
    }
    public function get_row($sql, $fetch_mode = MYSQLI_ASSOC) { return $this->getRow($sql); }
    public function cache_row($sql) {
        $sql    = $this->getQuerySql($sql, 1);
        return $this->get_cache($sql, 'getRow');
    }
    public function getAll($sql, $limit = null, $fetch_mode = MYSQLI_ASSOC) {
        $this->query($sql, $limit);
        $all_rows = array();
        $this->fetch_mode    = $fetch_mode;
        while($rows = $this->fetch()) {
            $all_rows[] = $rows;
        }
        $this->free();
        return $all_rows;
    }
    public function get_all($sql, $limit = null, $fetch_mode = MYSQLI_ASSOC) { return $this->getAll($sql); }
    public function cache_all($sql, $limit = null) {
        $sql    = $this->getQuerySql($sql, $limit);
        return $this->get_cache($sql, 'getAll');
    }
    public function insert_id() {
        return $this->mysqli->insert_id();
    }
    public function escape($str) {
        if(is_array($str)) {
            foreach($str as $key=>$val) {
                $str[$key] = $this->escape($val);
            }
        } else {
            $str = addslashes(trim($str));
        }
        return $str;
    }
}
//用法
$db    = new db_mysqli('localhost', 'root', 111222, 'dict');
$db->set_cache_time(10);
$db->set_cache_dir('./cache/sql/');
$sql = "select * from words order by word_id limit 10,10";
$res1 = $db->get_all($sql);
$res2 = $db->cache_all($sql);

echo $db->query_num(),'<br>';
?>