phpcms怎么判断用户是否登录

<?php
        $userid= param::get_cookie(&#39;_userid&#39;);
?>

{if $userid}   
       。。。这里写已经登录之后的代码。。。
{else}
{/if}

<?php 
defined(&#39;IN_PHPCMS&#39;) or exit(&#39;No permission resources.&#39;);
class MY_index extends index {
    private $times_db;
    public function __construct() {
        parent::__construct();
    }
	public function top_mini() {
		$_username = param::get_cookie(&#39;_username&#39;);
		$_userid = param::get_cookie(&#39;_userid&#39;);
		$siteid = isset($_GET[&#39;siteid&#39;]) ? intval($_GET[&#39;siteid&#39;]) : &#39;&#39;;
		$jsoncallback=isset($_GET[&#39;jsoncallback&#39;]) ? $_GET[&#39;jsoncallback&#39;] : &#39;&#39;;
		//定义站点id常量
		if (!defined(&#39;SITEID&#39;)) {
		   define(&#39;SITEID&#39;, $siteid);
		}
		if($_username){
			$res["success"]=1;
			$res["message"]=&#39;  &#39;.L(&#39;hellow&#39;).&#39;<a href="&#39;.APP_PATH.&#39;member-account_manage_avatar.html" target="_blank">;<img    style="max-width:90%" src="&#39;.get_memberavatar($_userid,1,30).&#39;"  style="max-width:90%"  style="max-width:90%" onerror="this.src=\&#39;&#39;.IMG_PATH.&#39;member/nophoto.gif\&#39;" alt="phpcms怎么判断用户是否登录" >;</a>; &#39;.get_nickname().&#39; 欢迎回家 <a href="&#39;.APP_PATH.&#39;member-index.html" target="_blank">;&#39;.L(&#39;member_center&#39;).&#39;</a>; | <a href="&#39;.APP_PATH.&#39;member-fabu.html" target="_top" class="upv_btn">;发布信息</a>; | <a href="&#39;.APP_PATH.&#39;member-logout.html">;&#39;.L(&#39;logout&#39;).&#39;</a>;&#39;;
			$res["message"] = pc_base::load_config(&#39;system&#39;, &#39;charset&#39;) == &#39;gbk&#39; ? iconv(&#39;utf-8&#39;, &#39;utf-8&#39;, $res["message"]) : $res["message"];
			//get_nickname();//,
			
			}
		else{
			$res["success"]=0;
			}
			
		if($jsoncallback){
      		echo $jsoncallback . "({\"items\":[".json_encode($res)."]})";
		}else{
			echo json_encode($res);
		}
		//echo json_encode($res);
	}

}
?>