PHP實現一個簡易的分頁類

class Paging {  
  private static $_Instance;  
  private function __clone(){}  
  public static function getInstance() {  
    if(empty(self::$_Instance)) self::$_Instance = new self();  
    return self::$_Instance;  
  }  
  
  protected $count = 0;  
  protected $size = 0;  
  protected $page = 0;  
  function prepare($sql, $pagesize=10) {  
    $page = isset($_GET['page']) ? $_GET['page'] : 1;  
    $pageon = ($page - 1) * $pagesize;  
    $sql = preg_replace('/select\s/i', '$0SQL_CALC_FOUND_ROWS ', $sql) . " limit $pageon, $pagesize";  
    $rs = mysql_query($sql);  
    $p = mysql_query('SELECT FOUND_ROWS()');  
    list($this->count) = mysql_fetch_row($p);  
    $this->size = $pagesize;  
    $this->page = $page;  
    return $rs;  
  }  
  function bar($tpl='') {  
    if(!$tpl) $tpl = '共{count}頁 第{page}頁 <a href=?{reset}>首頁</a> <a href=?{prve}>上一頁</a> <a href=?{next}>下一頁</a> <a href=?{end}>尾頁</a>';  
    $count = ceil($this->count / $this->size);  
    $page = $this->page;  
    $d = array(  
      '{reset}' => 1,  
      '{prve}' => $page > 1 ? $page - 1 : 1,  
      '{next}' => $page < $count ? $page + 1 : $page,  
      '{end}' => $count,  
      '{count}' => $count,  
      '{page}' => $page,  
    );  
    foreach($d as $k=>&$v) {  
      if(in_array($k, array('{reset}', '{prve}', '{next}', '{end}'))) {  
        $_GET['page'] = $v;  
        $v = http_build_query($_GET);  
      }  
    }  
    echo strtr($tpl, $d);  
  }  
}  
function mysql_paging_query($sql, $num=10) {  
  return Paging::getInstance()->prepare($sql, $num);  
}  
function mysql_paging_bar($tpl='') {  
  return Paging::getInstance()->bar($tpl);  
}  

include 'paging.php';  
$rs = mysql_paging_query($sql, 20);//替代 mysql_query  
mysql_paging_bar();//顯示分頁條