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。

网站查了很多资料，终于找到了一个合适、比较好用的代码，也希望能给大家一个参考。
复制代码 代码如下:
<?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";
}

?>

小编已经测试过了，是可以识别是电脑访问还是手机访问的。