php判断电脑访问或手机访问的方法

现在使用手机上网的人越来越多了，所以手机用户给网站带来流量也是非常可观的。但是对于像我这样的网站想让手机访问，那么体验度一定会很差，因为该站的css样式只适合用电脑浏览器访问。所以我就研究怎么用php去判断网页是电脑访问还是手机访问，然后再通过去加载不同的css来达到手机和电脑都可以正常的访问的效果。

<?php 

function check_wap() {  
	if (isset($_SERVER['HTTP_VIA'])) return true;  
	if (isset($_SERVER['HTTP_X_NOKIA_CONNECTION_MODE'])) return true;  
	if (isset($_SERVER['HTTP_X_UP_CALLING_LINE_ID'])) return true;  
	if (strpos(strtoupper($_SERVER['HTTP_ACCEPT']),"VND.WAP.WML") > 0) {  
		// Check whether the browser/gateway says it accepts WML.  
		$br = "WML";  
	} else {  
		$browser = isset($_SERVER['HTTP_USER_AGENT']) ? trim($_SERVER['HTTP_USER_AGENT']) : '';  
		if(empty($browser)) return true;
		$mobile_os_list=array('Google Wireless Transcoder','Windows CE','WindowsCE','Symbian','Android','armv6l','armv5','Mobile','CentOS','mowser','AvantGo','Opera Mobi','J2ME/MIDP','Smartphone','Go.Web','Palm','iPAQ');  
					
		$mobile_token_list=array('Profile/MIDP','Configuration/CLDC-','160×160','176×220','240×240','240×320','320×240','UP.Browser','UP.Link','SymbianOS','PalmOS','PocketPC','SonyEricsson','Nokia','BlackBerry','Vodafone','BenQ','Novarra-Vision','Iris','NetFront','HTC_','Xda_','SAMSUNG-SGH','Wapaka','DoCoMo','iPhone','iPod');  
					
		$found_mobile=checkSubstrs($mobile_os_list,$browser) ||  
							checkSubstrs($mobile_token_list,$browser); 
	if($found_mobile)
		$br ="WML";
	else $br = "WWW";
	}  
	if($br == "WML") {  
		return true;  
	} else {  
		return false;  
	}  
}

function checkSubstrs($list,$str){
	$flag = false;
	for($i=0;$i<count($list);$i++){
		if(strpos($str,$list[$i]) > 0){
			$flag = true;
			break;
		}
	}
	return $flag;
}

if(check_wap()){
	echo "wap";
}else{
	echo "web";
}

?>