PHP根据URL参数变换引入html模板

<div>
    <p>
        <a href="?oa">
            <span>OA</span>
        </a>
    </p>
    <p>
        <a href="?ob">
            <span>OC</span>
        </a>
    </p>
    <p>
        <a href="?oc">
            <span>OC</span>
        </a>
    </p>
</div>

#获取URL参数，作为文件名
$fileName = $_SERVER["QUERY_STRING"];
if(empty($fileName)){
    $fileName = "index";
}
#引入模板页面
include "templates/".$fileName.".html";