PHP實現數據分頁的通用方法

function show_page($count,$page,$page_size)
{
    $page_count  = ceil($count/$page_size);  //計算得出總頁數
    $init=1;
    $page_len=7;
    $max_p=$page_count;
    $pages=$page_count;
    //判斷當前頁碼
    $page=(empty($page)||$page<0)?1:$page;
    //獲取當前頁url
    $url = $_SERVER['REQUEST_URI'];
    //去掉url中原先的page參數以便加入新的page參數
    $parsedurl=parse_url($url);
    $url_query = isset($parsedurl['query']) ? $parsedurl['query']:'';
    if($url_query != ''){
        $url_query = preg_replace("/(^|&)page=$page/",'',$url_query);
        $url = str_replace($parsedurl['query'],$url_query,$url);
        if($url_query != ''){
            $url .= '&';
        }
    } else {
        $url .= '?';
    }   
    //分頁功能代碼
    $page_len = ($page_len%2)?$page_len:$page_len+1;  //頁碼個數
    $pageoffset = ($page_len-1)/2;  //頁碼個數左右偏移量
    $navs='';
    if($pages != 0){
        if($page!=1){
            $navs.="<a href=\"".$url."page=1\">首頁</a> ";      //第一頁
            $navs.="<a href=\"".$url."page=".($page-1)."\">上頁</a>"; //上一頁
        } else {
            $navs .= "<span class='disabled'>首頁</span>";
            $navs .= "<span class='disabled'>上頁</span>";
        }
        if($pages>$page_len)
        {
            //如果當前頁小于等于左偏移
            if($page<=$pageoffset){
                $init=1;
                $max_p = $page_len;
            }
            else  //如果當前頁大于左偏移
            {    
                //如果當前頁碼右偏移超出最大分頁數
                if($page+$pageoffset>=$pages+1){
                    $init = $pages-$page_len+1;
                }
                else
                {
                    //左右偏移都存在時的計算
                    $init = $page-$pageoffset;
                    $max_p = $page+$pageoffset;
                }
            }
        }
        for($i=$init;$i<=$max_p;$i++)
        {
            if($i==$page){$navs.="<span class='current'>".$i.'</span>';} 
            else {$navs.=" <a href=\"".$url."page=".$i."\">".$i."</a>";}
        }
        if($page!=$pages)
        {
            $navs.=" <a href=\"".$url."page=".($page+1)."\">下頁</a> ";//下一頁
            $navs.="<a href=\"".$url."page=".$pages."\">末頁</a>";    //最后一頁
        } else {
            $navs .= "<span class='disabled'>下頁</span>";
            $navs .= "<span class='disabled'>末頁</span>";
        }
        echo "$navs";
   }
}