PHP无法获取Referer问题排查

<?php echo <span>'测试来源：直接载入页面<br>';

echo <span>'<a href="test_cookie.php">进入页面</a><br>'</span>;

echo <span>'测试来源：新窗口打开<br>'</span>;

echo <span>'<a target="_blank" href="test_cookie.php">进入页面</a><br>'</span>;

<?php date_default_timezone_set(<span>'Asia/Shanghai');<span>//设置默认时区</span>header(<span>'content-type:text/html; charset=utf8'</span>);<span>//设置返回头信息</span>
echo date(<span>'Y-m-d H:i:s'</span>);
echo <span>"<br>\r\n"</span>;

echo <span>'PHP获取Refer是：'</span>;
$refer=isset($_SERVER[<span>'HTTP_REFERER'</span>])?$_SERVER[<span>'HTTP_REFERER'</span>]:<span>'No refer found'</span>;
echo $refer;
echo <span>"<br>\r\n"</span>;

echo <span>'JS获取Refer是：'</span>;
    echo <span>"<script>document.writeln(document.referrer);</script>"</span>;
echo <span>"<br>\r\n"</span>;