PHP实现适用于文件内容操作的分页类

<?php 
class StrPage {
 private $current;  //当前页 
 private $file;  //操作文件
 private $totalPage;  //总的页数
 private $url;  //传递的参数
 private $pageLen;  //每页显示的长度
 
 function __construct( $file,$len = 200 ){
 $this->file = file_get_contents($file);
 $this->pageLen = $len;
 $this->current = isset($_GET['page'])?$_GET['page']:1;
 $this->totalPage = $this->getTotalPage();
 $this->url = $this->getUrl();
 }
 
 
 //获取到这个文件总的长度
 private function getTotalPage(){
 return ceil(strlen($this->file)/$this->pageLen);
 }
 
 //获取当前传递的参数,保留参数，page参数动态变化
 private function getUrl(){
 $url =parse_url($_SERVER['REQUEST_URI']);
 parse_str($url['query'],$queryArr);
 unset($queryArr['page']);
 $queryStr = http_build_query($queryArr);
 return $url['path'].'?'.$queryStr.'&page='; 
 }
 
 
 //首页
 private function first(){
 if($this->current>1)
  return "<a href='".$this->url."1'>首页</a>";
 }
 //上一页
 private function pre(){
 if( $this->current > 1 )
  return "<a href='".$this->url.($this->current-1)."'>上一页</a>";
 }
 //下一页
 private function next(){
 if( $this->current < $this->totalPage)
  return "<a href='".$this->url.($this->current+1)."'>下一页</a>";
 }
 //最后一页
 private function end(){
 if( $this->current < $this->totalPage )
  return "<a href='".$this->url.$this->totalPage."'>末页</a>";
 }
 
 public function pageList(){
 $pageListStr = '';
 for ($i=1;$i<=$this->totalPage;$i++){
  if($i==$this->current){
  $pageListStr.="<span style='font-size:20px;color:#f00'>".$i."</span>&nbsp;";
  }else{
  $pageListStr.="<a href='".$this->url.$i."'>".$i."&nbsp;</a>";
  }
 }
 return $pageListStr;
 }
 
 public function pageStyle($style=1){
  switch ($style){
  case 1:
   return "共有".$this->totalPage."页".$this->first().$this->pre().$this->pageList().$this->next().$this->end();
   break;
  case 2;
  return $this->pageList();
  break;
  }
 }
 
 public function getContents(){
 $prePageLen = strlen($this->subStrs($this->current-1));
 $currentPageLen = strlen($this->subStrs($this->current));
 return substr($this->file, $prePageLen,$currentPageLen-$prePageLen);
 }
 
 public function subStrs($page){ 
  $string = '';
  $len= $page*$this->pageLen;
  for( $i=0; $i<$len; $i++ ){
   if( ord(substr($this->file,$i,1))>0xa0 ){
   $string .= substr($this->file,$i,3);
   $i = $i+2;
  }else{
   $string .= substr($this->file, $i,1);
  }
  }
  return $string;
  
 }
 
}