网上找了个数据库备份类，却不知道该如何用，求解答

<?php <br />    /**<br>        file: dbbackup.class.php<br>        数据库备份类文件，备份文件放在/backup 目录下<br>        package: sql<br>    */<br>    date_default_timezone_set('PRC');                              //设置时区<br>    <br>    class Dbbackup {<br>        private $path = "sql/backup/";                           //SQL文件保存路径，默认为/backup<br>        private $database;                                         //所要备份的数据库的名称<br>        private $size;                                             //分卷分件大小<br>        private $fileName;                                         //SQL文件名<br>        <br>        private $ds = "\n";                                        //换行符<br>        private $sqlEnd = ";";                                     //每条SQL语句的结尾符号<br>        <br>        <br>        /**<br>        *构造方法，用来实例化备份类对象<br>        [email protected]    string    $database      数据库名称，默认值为‘lighting’<br>        [email protected]    int       $size          分卷文件大小，默认值为2048<br>        */<br>        function __construct($size = 2048, $database = 'lighting') {<br>            $this-&gt;database = $database;                           //设置所要备份的数据库，默认为 lighting<br>            $this-&gt;size = $size;                                   //分卷文件大小，默认为2MB<br>            $this-&gt;fileName = date('YmdHis')."_all";<br>            <br>            ob_end_flush();                                        //清除所有缓存<br>        }<br>        <br>        /**<br>        *公用方法，进行数据库备份<br>        [email protected] bool   是否备份成功<br>        */<br>        public function backup() {<br>            $sqlFile = '';                                         //准备写入数据库的信息<br>            <br>            $this-&gt;showMess("正在备份");<br>            /*备份指定数据库中所有的数据表*/<br>            if ($tables = mysql_query( "SHOW TABLE STATUS FROM ".$this-&gt;database)) {<div class="clear"></div>