$_SERVER['HTTP_REFERER']将为您提供引荐来源页面的URL(如果存在).如果用户使用书签或通过手动输入URL直接访问您的网站，则http_referer将为空.同样，如果用户以编程方式(CURL)发布到您的页面，则他们也没有义务设置http_referer.您错过了所有_，是错字吗?

$_SERVER['HTTP_REFERER'] will give you the referrer page's URL if there exists any. If users use a bookmark or directly visit your site by manually typing in the URL, http_referer will be empty. Also if the users are posting to your page programatically (CURL) then they're not obliged to set the http_referer as well. You're missing all _, is that a typo?