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。
复制代码 代码如下:
<?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;
}
};
?>