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。

<?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; 
} 
}; 
?>