封装分页类

<?php
class Page{
protected $total; //数据的总条数
protected $listRows; //一页显示多少条
protected $currentPage; //当前页
protected $countPage; //总的页数


public function __construct($total,$listRows="10"){
$this->total=$total;
$this->listRows=$listRows;


if(isset($_GET['page']) && $_GET['page']>0 ){
$this->currentPage=$_GET['page'];
}else{
$this->currentPage=1;
}
if($this->total<=0){
 return '';
}else{
$this->countPage=ceil($this->total / $this->listRows);
}


}
function showPage(){
$url=$_SERVER['REQUEST_URI'];
$parse_url=parse_url($url);
//print_r($parse_url);
if(!isset($parse_url['query'])){
     $pase_url['query']="page=".$this->currentPage;
}
//print_r($parse_url['query']);
parse_str($parse_url['query'],$parms);
if(!array_key_exists('page',$parms)){
     $parms['page']=$this->currentPage;
}
if(count($parms)==1){
     $url=$parse_url['path']."?";
    // echo $url;
}else{
    unset($parms['page']);
     $url=$parse_url['path']."?".http_build_query($parms)."&";
     //print_r($url);
     
}
$prev=$this->currentPage-1;
$next=$this->currentPage+1;
$header='<a href="' . $url .'page=' . 1 . '">首页</a>';
$last='<a href="' . $url .'page=' . $this->countPage . '">尾页</a>';
if($prev<1){
     $prevPage='';
}else{
$prevPage='<a href="' . $url .'page=' . $prev . '">上一页</a>';
}
if($next>$this->countPage){
     $nextPage='';
}else{
$nextPage='<a href="' . $url .'page=' . $next . '">下一页</a>';
}
$start = $this->currentPage - (5-1)/2; //计算左侧开始的页码
$end = $this->currentPage + (5-1)/2;//计算右侧开始的页码

//如果左侧的页面，已经小于1，则把小于1 的部分补到右侧
if ($start < 1) {
$end += (1 - $start);
$start = 1; //修改start = 1

if ($end > $this->countPage) {
$end  = $this->countPage;
}
}


//把右侧超出的部分，补到左边
if ($end > $this->countPage) {
$start -= ($end - $this->countPage);
$end = $this->countPage;


if ($start < 1) {
$start = 1;
}
}
$pagestr='';
for ($i=$start; $i <= $end ; $i++) { 

if ($i == $this->currentPage) {
$pagestr .= $i;
continue;
}
$pagestr.='<a href="' . $url . 'page=' . $i . '">' . $i . '</a>';
}
return $header.$prevPage.$pagestr.$nextPage.$last;
}




}
$page=new Page(30,3);
echo $page->showPage();
?>