php实现的仿阿里巴巴实现同类产品翻页

如果左边的记录条数小于$space(页码区段)的值，页码$start从1开始向右增值。如果左则的记录条数多于$left(左右各显示页数)的值，$start将从左边记录数减去$left值开始记数。

<?php
/** 实现同类产品翻页 **/

class pager
{
protected $space;
protected $left;
protected $db;
protected $pagename;

public function setspace($num) {
$this->space = $num;
$this->left = ceil(($num-1)/2);
}

public function setdb(&$db) {
$this->db = $db;
}

public function setpagename($pagename) {
$this->pagename = $pagename;
}

public function getpages($catid, $exptime) {
$fields = array("`id`,`title`");
$left = array(">" => array("exptime"=>$exptime), "memberid" => gs(_mem_prefix_ . "memberid"), "catid"=>$catid);
$right = array("<" => array("exptime"=>$exptime), "memberid" => gs(_mem_prefix_ . "memberid"), "catid"=>$catid);

$leftcount = $this->db->getcount($left);

if($leftcount <= $this->left) {
$star = 1;
$leftlimit = "limit" . $leftcount;
$rightlimit = "limit " . ($this->space-$leftcount);
}
else {
$start = $leftcount - $this->left;
$leftlimit = "limit " . $this->left;
$rightlimit = $leftlimit;
}

$list1 = $this->db->findall($left, array("exptime"=>"asc"), $leftlimit, $fields);
$list2 = $this->db->findall($right, array("exptime"=>"desc"), $rightlimit, $fields);

/** 上一页链接 **/
$c = count($list1);
if($c > 1) {
$url = $this->pagename."-".$list1[$c]['id'].".html";
$pages = "<a href=\"{$url}\">上一页</a><ol>";
}elseif($c == 1) {
$url = $this->pagename."-".$list1[0]['id'].".html";
$pages = "<a href=\"{$url}\">上一页</a><ol>";
}else {
$pages = "";
}


/** 当前页的左边内容 **/
foreach($list1 as $item) {
$url = $this->pagename."-".$item['id'].".html";
$pages .= "<li><a href=\"{$url}\">{$start}</a></li>";
$start++;
}

$pages .= "<li><b>{$leftcount}</b></li>";
$start++;

/** 当前页面右边的内容 **/
foreach($list1 as $item) {
$url = $this->pagename."-".$item['id'].".html";
$pages .= "<li><a href=\"{$url}\">{$start}</a></li>";
$start++;
}

/** 下一页的链接 **/
$c = count($list2);
if($c > 0) {
$url = $this->pagename."-".$list2[0]['id'].".html";
$pages .= "<a href=\"{$url}\">下一页</a><ol>";
}else {
$pages .= "";
}

return $pages;
}
};
?>