Simple paging class implemented in PHP and usage examples_php skills

<?php
/*
 * 使用:
 * $page = new page(连接符,查询语句,当前页码,每页大小,页码符)
 * 连接符:一个mysql连接标识符,如果该参数留空,则使用最近一个连接
 * 查询语句:sql语句
 * 当前页码:指定当前是第几页
 * 每页大小:每页显示的记录数
 * 页码符:指定当前页面url格式
 *
 * 使用例子:
 * $sql = "select * from aa";
 * $page = new page($conn,$sql,$_get['page'],4,"?page=");
 *
 * 获得当前页码
 * $page->page;
 *
 * 获得总页数
 * $page->pagecount;
 *
 * 获得总记录数
 * $page->rowcount;
 *
 * 获得本页记录数
 * $page->listsize;
 *
 * 获得记录集
 * $page->list;
 * 记录集是一个2维数组,例:list[0]['id']访问第一条记录的id字段值.
 *
 * 获得页码列表
 * $page->getpagelist();
 */
class page
{
  //基础数据
  var $sql;
  var $page;
  var $pagesize;
  var $pagestr;
  //统计数据
  var $pagecount; //页数
  var $rowcount; //记录数
  //结果数据
  var $list = array(); //结果行数组
  var $listsize ;
  //构造函数
  function page($conn,$sql_in,$page_in,$pagesize_in,$pagestr_in)
  {
    $this->sql = $sql_in;
    $this->page = intval($page_in);
    $this->pagesize = $pagesize_in;
    $this->pagestr = $pagestr_in;
    //页码为空或小于1的处理
    if(!$this->page||$this->page<1)
    {
      $this->page = 1;
    }
    //查询总记录数
    $rowcountsql = preg_replace("/([\w\w]*?select)([\w\w]*?)(from[\w\w]*?)/i","$1 count(0) $3",$this->sql);
    if(!$conn)
      $rs = mysql_query($rowcountsql) or die("bnc.page: error on getting rowcount.");
    else
      $rs = mysql_query($rowcountsql,$conn) or die("bnc.page: error on getting rowcount.");
    $rowcountrow = mysql_fetch_row($rs);
    $this->rowcount=$rowcountrow[0];
    //计算总页数
    if($this->rowcount%$this->pagesize==0)
      $this->pagecount = intval($this->rowcount/$this->pagesize);
    else
      $this->pagecount = intval($this->rowcount/$this->pagesize)+1;
    //sql偏移量
    $offset = ($this->page-1)*$this->pagesize;
    if(!$conn)
      $rs = mysql_query($this->sql." limit $offset,".$this->pagesize) or die("bnc.page: error on listing.");
    else
      $rs = mysql_query($this->sql." limit $offset,".$this->pagesize,$conn) or die("bnc.page: error on listing.");
    while($row=mysql_fetch_array($rs))
    {
      $this->list[]=$row;
    }
    $this->listsize = count($this->list);
  }
  /*
   * getpagelist方法生成一个较简单的页码列表
   * 如果需要定制页码列表,可以修改这里的代码,或者使用总页数/总记录数等信息进行计算生成.
   */
  function getpagelist()
  {
    $firstpage;
    $previouspage;
    $pagelist;
    $nextpage;
    $lastpage;
    $currentpage;
    //如果页码>1则显示首页连接
    if($this->page>1)
    {
      $firstpage = "<a href=\"".$this->pagestr."1\">首页</a>";
    }
    //如果页码>1则显示上一页连接
    if($this->page>1)
    {
      $previouspage = "<a href=\"".$this->pagestr.($this->page-1)."\">上一页</a>";
    }
    //如果没到尾页则显示下一页连接
    if($this->page<$this->pagecount)
    {
      $nextpage = "<a href=\"".$this->pagestr.($this->page+1)."\">下一页</a>";
    }
    //如果没到尾页则显示尾页连接
    if($this->page<$this->pagecount)
    {
      $lastpage = "<a href=\"".$this->pagestr.$this->pagecount."\">尾页</a>";
    }
    //所有页码列表
    for($counter=1;$counter<=$this->pagecount;$counter++)
    {
      if($this->page == $counter)
      {
        $currentpage = "<b>".$counter."</b>";
      }
      else
      {
        $currentpage = " "."<a href=\"".$this->pagestr.$counter."\">".$counter."</a>"." ";
      }
      $pagelist .= $currentpage;
    }
    return $firstpage." ".$previouspage." ".$pagelist." ".$nextpage." ".$lastpage." ";
  }
}
?>

<?php
@$db = mysql_connect('localhost', 'root', '123456') or
    die("Could not connect to database.");//连接数据库
mysql_query("set names 'utf8'");//输出中文
mysql_select_db('test');    //选择数据库
$sql = "select * from `users`"; //一个简单的查询
$page = new Page('',$sql,$_GET['page'],5,"?page=");
$rows = $page->list;
foreach($rows as $row)
{
  echo $row['UserName']."<br>";
}
echo $page->getPageList(); //输出分页列表
?>