仿阿里巴巴同级产品翻页的实现

]<?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";
$pages = "<a href="/" mce_href="/""{$url}/">上一页</a><ol>";
}elseif($c == 1) {
$url = $this->pageName."-".$list1[0]['id'].".html";
$pages = "<a href="/" mce_href="/""{$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";
$pages .= "<li><a href="/" mce_href="/""{$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";
$pages .= "<li><a href="/" mce_href="/""{$url}/">{$start}</a></li>";
$start++;
}
/** 下一页的链接 **/
$c = count($list2);
if($c > 0) {
$url = $this->pageName."-".$list2[0]['id'].".html";
$pages .= "<a href="/" mce_href="/""{$url}/">下一页</a><ol>";
}else {
$pages .= "";
}
return $pages;
}
};
?>

$B = Factory::loadCommon("Brothers");
$B->setSpace(9);
$B->setPageName($pagename);
$B->setDB($this->DB);
$pp = $B->getPages($id, $product['memberid'], $product['catid']);
$catTotal = $B->getTotal($product['memberid'], $product['catid']);
$this->response->set("brothers", $pp);
$this->response->set("catTotal", $catTotal);

当前页左边的页码为最新的产品，按更新时间呈升序排列；右边的页码为早期的产品， 按更新时间呈降序排列。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。