/** 
 * 
 * 关于 页码有效性的判断需要加在 控制器中判断，即当页码数<1或者>总页数 
 * 
 */ 
class Custom_pagination 
{ 
  var $page_url = ''; //分页目标URL 
  var $page_size = 10; //每一页行数 
  var $page_num = 1;//页码 
  var $rows_num= '';//数据总行数 
  var $links_num= 3;//选中链接前后的链接数，必须大于等于1 
 
  var $anchor_class= '';//链接样式类 
  var $current_class= '';//当前页样式类 
  var $full_tag_open= '';//分页开始标签 
  var $full_tag_close= '';//分页结束标签 
  var $info_tag_open= ''; 
  var $info_tag_close= ' '; 
  var $first_tag_open= ''; 
  var $first_tag_close= ' '; 
  var $last_tag_open= ' '; 
  var $last_tag_close= ''; 
  var $cur_tag_open= ' '; 
  var $cur_tag_close= ''; 
  var $next_tag_open= ' '; 
  var $next_tag_close= ' '; 
  var $prev_tag_open= ' '; 
  var $prev_tag_close= ''; 
  var $num_tag_open= ' '; 
  var $num_tag_close= ''; 
 
  public function __construct($params = array()) 
  { 
    if (count($params) > 0) 
    { 
      $this->init($params); 
    } 
  } 
  
  function init($params = array()) //初始化数据 
  { 
    if (count($params) > 0) 
    { 
      foreach ($params as $key => $val) 
      { 
        if (isset($this->$key)) 
        { 
          $this->$key = $val; 
        } 
      } 
    } 
  } 
  
  function create_links() 
  { 
    /////////////////////////////////////////////////////// 
    //准备数据 
    /////////////////////////////////////////////////////// 
    $page_url = $this->page_url; 
    $rows_num = $this->rows_num; 
    $page_size = $this->page_size; 
    $links_num = $this->links_num; 
 
    if ($rows_num == 0 OR $page_size == 0) 
    { 
      return ''; 
    } 
 
    $pages = intval($rows_num/$page_size); 
    if ($rows_num % $page_size) 
    { 
      //有余数pages+1 
      $pages++; 
    }; 
    $page_num = $this->page_num < 1 ? '1' : $this->page_num; 
 
    $anchor_class = ''; 
    if($this->anchor_class !== '') 
    { 
      $anchor_class = 'class="'.$this->anchor_class.'" '; 
    } 
 
    $current_class = ''; 
    if($this->current_class !== '') 
    { 
      $current_class = 'class="'.$this->current_class.'" '; 
    } 
    if($pages == 1) 
    { 
      return ''; 
    } 
    if($links_num < 0) 
    { 
      return '- -！links_num必须大于等于0'; 
    } 
    //////////////////////////////////////////////////////// 
    //创建链接开始 
    //////////////////////////////////////////////////////// 
    $output = $this->full_tag_open; 
    $output .= $this->info_tag_open.'共'.$rows_num.'条数据 第 '.$page_num.'/'.$pages.' 页'.$this->info_tag_close; 
    //首页 
    if($page_num > 1) 
    { 
      $output .= $this->first_tag_open.'首页'.$this->first_tag_close; 
    } 
    //上一页 
    if($page_num > 1) 
    { 
      $n = $page_num - 1; 
      $output .= $this->prev_tag_open.'上一页'.$this->prev_tag_close; 
    } 
    //pages 
    for($i=1;$i<=$pages;$i++) 
    { 
      $pl = $page_num - $links_num < 0 ? 0 : $page_num - $links_num; 
      $pr = $page_num + $links_num > $pages ? $pages : $page_num + $links_num; 
      //判断链接个数是否太少，举例，假设links_num = 2，则链接个数不可少于 5 个，主要是 当page_num 等于 1， 2 和 n，n-1的时候 
      if($pr < 2 * $links_num + 1) 
      { 
        $pr = 2 * $links_num + 1; 
      } 
      if($pl > $pages-2 * $links_num) 
      { 
        $pl = $pages - 2 * $links_num; 
      } 
      if($i == $page_num) 
      {  //current page 
        $output .= $this->cur_tag_open.''.$i.''.$this->cur_tag_close; 
      }else if($i >= $pl && $i <= $pr) 
      { 
        $output .= $this->num_tag_open.''.$i.''.$this->num_tag_close; 
      } 
    } 
    //下一页 
    if($page_num < $pages) 
    { 
      $n = $page_num + 1; 
      $output .= $this->next_tag_open.'下一页'.$this->next_tag_close; 
    } 
    //末页 
    if($page_num < $pages) 
    { 
      $output .= $this->last_tag_open.'末页'.$this->last_tag_close; 
    } 
 
    $output.=$this->full_tag_close; 
    return $output; 
  } 
} 

$config['page_url'] 
= 'about/science'; 
$config['page_size'] = $pagesize; 
$config['rows_num'] = $num_rows; 
$config['page_num'] = $page; 
$this->load->library('Custom_pagination'); 
$this->custom_pagination->init($config); 
echo $this->custom_pagination->create_links(); 

pagenum = ceil($count/$pagesize); 
    $this->pagesize = $pagesize; 
    $this->page =(isset($_GET['p'])&&$_GET['p']>0) ? intval($_GET['p']) : 1; 
  } 
  /** 
   * 获得 url 后面GET传递的参数 
   */  
  public function getUrl(){   
    $url = 'index.php?'.http_build_query($_GET); 
    $url = preg_replace('/[?,&]p=(\w)+/','',$url); 
    $url .= (strpos($url,"?") === false) ? '?' : '&'; 
    return $url; 
  } 
  /** 
   * 获得分页HTML 
   */ 
  public function getPage(){ 
    $url = $this->getUrl(); 
    $start = $this->page-5; 
    $start=$start>0 ? $start : 1;  
    $end  = $start+9; 
    $end = $end<$this->pagenum ? $end : $this->pagenum; 
    $pagestr = ''; 
    if($this->page>5){ 
      $pagestr = "首页 "; 
    } 
    if($this->page!=1){ 
      $pagestr.= "上一页"; 
    } 
     
    for($i=$start;$i<=$end;$i++){ 
      $pagestr.= "".$i." ";            
    } 
    if($this->page!=$this->pagenum){ 
      $pagestr.="下一页"; 
       
    } 
    if($this->page+5<$this->pagenum){ 
      $pagestr.="尾页 "; 
    } 
    return $pagestr;   
  } 
   
} 
// 测试代码 
$page = new page(100,10); 
$str=$page->getPage(); 
echo $str; 
?>