php实现分页功能的3种方法

public function query($query)///这个函数有问题，暂时可以不用
{
$ret = false;
if (!empty($query)) {
  if ($this->_conn === false || !is_resource($this->_conn)) {
   warningLog(__METHOD__ . ': query sql with no connection',true);
  return false;
  }
$this->_query_id = @mysql_query($query,$this->_conn);
if ($this->_query_id === false) {
$this->_errstr = @mysql_error();
$ret = false;
 } else {
$this->_errstr = 'SUCCESS';
$ret = $this->_query_id;
  }
}
 $msg = ($ret === false) ? 'false' : strval($ret);
 debugLog(__METHOD__.": [$msg] returned for sql query [$query]");
return $ret;
}

function __construct($sql,$page_size) {
$result = mysql_query($sql);
$datanum = mysql_num_rows($result);
$this->sql=$sql;
$this->datanum=$datanum;
$this->page_size=$page_size;
}

//当前页数
public function page_id() {
  if($_SERVER['QUERY_STRING'] == ""){
    return 1;
  }elseif(substr_count($_SERVER['QUERY_STRING'],"page_id=") == 0){
    return 1;
  }else{
    return intval(substr($_SERVER['QUERY_STRING'],8));
  }
}

//剩余url值
public function url() {
  if($_SERVER['QUERY_STRING'] == ""){
    return "";
  }elseif(substr_count($_SERVER['QUERY_STRING'],"page_id=") == 0){
    return "&".$_SERVER['QUERY_STRING'];
  }else{
    return str_replace("page_id=".$this->page_id(),"",$_SERVER['QUERY_STRING']);
  }
}

//总页数
public function page_num() {
  if($this->datanum == 0){
    return 1;
  }else{
    return ceil($this->datanum/$this->page_size);
  }
}

//数据库查询的偏移量
public function start() {
return ($this->page_id()-1)*$this->page_size;
}

//数据输出
public function sqlquery() {
  return $this->sql." limit ".$this->start().",".$this->page_size;
}

//获取当前文件名
private function php_self() {
  return $_SERVER['PHP_SELF'];
}

//上一页
private function pre_page() {
  if ($this->page_id() == 1) { //页数等于1
    return "<a href=".$this->php_self()."?page_id=1".$this->url()."&gt;上一页</a> ";
  }elseif ($this->page_id() != 1) { //页数不等于1
    return "<a href=".$this->php_self()."?page_id=".($this->page_id()-1).$this->url()."&gt;上一页</a> ";
  }
}

//显示分页
private function display_page() {
  $display_page = "";
  if($this->page_num() <= 10){ //小于10页
    for ($i=1;$i<=$this->page_num();$i++) //循环显示出页面
      $display_page .= "<a href=".$this->php_self()."?page_id=".$i.$this->url()."&gt;".$i."</a> ";
      return $display_page;
  }elseif($this->page_num() > 10){ //大于10页
    if($this->page_id() <= 6){
      for ($i=1;$i<=10;$i++) //循环显示出页面
        $display_page .= "<a href=".$this->php_self()."?page_id=".$i.$this->url()."&gt;".$i."</a> ";
        return $display_page;
    }elseif(($this->page_id() > 6) && ($this->page_num()-$this->page_id() >= 4)){
      for ($i=$this->page_id()-5;$i<=$this->page_id()+4;$i++) //循环显示出页面
        $display_page .= "<a href=".$this->php_self()."?page_id=".$i.$this->url()."&gt;".$i."</a> ";

return $display_page;
}elseif(($this->page_id() > 6) && ($this->page_num()-$this->page_id() < 4)){
for ($i=$this->page_num()-9;$i<=$this->page_num();$i++) //循环显示出页面
$display_page .= "<a href=".$this->php_self()."?page_id=".$i.$this->url().">".$i." ";
return $display_page;
}
}
}

//下一页
private function next_page() {
  if ($this->page_id() < $this->page_num()) { //页数小于总页数
    return "<a href=".$this->php_self()."?page_id=".($this->page_id()+1).$this->url()."&gt;下一页</a> ";
  }elseif ($this->page_id() == $this->page_num()) { //页数等于总页数
    return "<a href=".$this->php_self()."?page_id=".$this->page_num().$this->url()."&gt;下一页</a> ";
  }
}

// 设置分页信息
public function set_page_info() {
  $page_info = "共".$this->datanum."条 ";
  $page_info .= "<a href=".$this->php_self()."?page_id=1".$this->url()."&gt;首页</a> ";
  $page_info .= $this->pre_page();
  $page_info .= $this->display_page();
  $page_info .= $this->next_page();
  $page_info .= "<a href=".$this->php_self()."?page_id=".$this->page_num().$this->url()."&gt;尾页</a> ";
  $page_info .= "第".$this->page_id()."/".$this->page_num()."页";
  return $page_info;
}

}
?>

// while($info = mysql_fetch_array($res_1,MYSQL_ASSOC)){
echo $info["word"]."
";
}
// 页码索引条
echo $page->set_page_info();

?>