我們可以通過HTTP_USER_AGENT來判斷是否是蜘蛛，搜索引擎的蜘蛛都有自己的獨特標誌，下面列取了壹部分。
function?is_crawler()?{? $userAgent?=?strtolower($_SERVER['HTTP_USER_AGENT']);? $spiders?=?array(?'Googlebot',?//?Google?爬蟲?
'Baiduspider',?//?百度爬蟲?
'Yahoo!?Slurp',?//?雅虎爬蟲?
'YodaoBot',?//?有道爬蟲?
'msnbot'?//?Bing爬蟲?
//?更多爬蟲關鍵字?
);? foreach?($spiders?as?$spider)?{?$spider?=?strtolower($spider);?
if?(strpos($userAgent,?$spider)?!==?false)?{?
return?true;?}?
}? return?false;?}
下面的php代碼附帶了更多的蜘蛛標識
function?isCrawler()?{?
echo?$agent=?strtolower($_SERVER['HTTP_USER_AGENT']);?
if?(!empty($agent))?{?
$spiderSite=?array(?
"TencentTraveler",?
"Baiduspider+",?
"BaiduGame",?
"Googlebot",?
"msnbot",?
"Sosospider+",?
"Sogou?web?spider",?
"ia_archiver",?
"Yahoo!?Slurp",?
"YoudaoBot",?
"Yahoo?Slurp",?
"MSNBot",?
"Java?(Often?spam?bot)",?
"BaiDuSpider",?
"Voila",?
"Yandex?bot",?
"BSpider",?
"twiceler",?
"Sogou?Spider",?
"Speedy?Spider",?
"Google?AdSense",?
"Heritrix",?
"Python-urllib",?
"Alexa?(IA?Archiver)",?
"Ask",?
"Exabot",?
"Custo",?
"OutfoxBot/YodaoBot",?
"yacy",?
"SurveyBot",?
"legs",?
"lwp-trivial",?
"Nutch",?
"StackRambler",?
"The?web?archive?(IA?Archiver)",?
"Perl?tool",?
"MJ12bot",?
"Netcraft",?
"MSIECrawler",?
"WGet?tools",?
"larbin",?
"Fish?search",?
);?
foreach($spiderSite?as?$val)?{?
$str?=?strtolower($val);?
if?(strpos($agent,?$str)?!==?false)?{?
return?true;?
}?
}?
}?else?{?
return?false;?
}?
}?
if?(isCrawler()){?
echo?"妳好蜘蛛精！";?
}?
else{?
echo?"妳不是蜘蛛精啊！";
妳試壹下看行不行，我沒試過。