随着移动设备的普及，网站也会迎来越来越多移动设备的访问。用适应PC的页面，很多时候对手机用户不友好，那么有些时候，我们需要判断用户是否用手机访问，如果是手机的话，就跳转到指定的手机友好页面。这里就介绍一下，如何判断用户是否用手机访问。

自定义的函数如下：

// check if wap
function check_wap(){
	// 先检查是否为wap代理，准确度高
	if(stristr($_SERVER['HTTP_VIA'],"wap")){
		return true;
	}
	// 检查浏览器是否接受 WML.
	elseif(strpos(strtoupper($_SERVER['HTTP_ACCEPT']),"VND.WAP.WML") > 0){
		return true;
   }
   //检查USER_AGENT
   elseif(preg_match('/(blackberry|configuration\/cldc|hp |hp-|htc |htc_|htc-|iemobile|kindle|midp|mmp|motorola|mobile|nokia|opera mini|opera |Googlebot-Mobile|YahooSeeker\/M1A1-R2D2|android|iphone|ipod|mobi|palm|palmos|pocket|portalmmm|ppc;|smartphone|sonyericsson|sqh|spv|symbian|treo|up.browser|up.link|vodafone|windows ce|xda |xda_)/i', $_SERVER['HTTP_USER_AGENT'])){
		return true;
	}
	else{
		return false;
   }
}

function is_mobile_request()
{
  $_SERVER['ALL_HTTP'] = isset($_SERVER['ALL_HTTP']) ? $_SERVER['ALL_HTTP'] : '';
  $mobile_browser = '0';
  if(preg_match('/(up.browser|up.link|mmp|symbian|smartphone|midp|wap|phone|iphone|ipad|ipod|android|xoom)/i', strtolower($_SERVER['HTTP_USER_AGENT'])))
	$mobile_browser++;
  if((isset($_SERVER['HTTP_ACCEPT'])) and (strpos(strtolower($_SERVER['HTTP_ACCEPT']),'application/vnd.wap.xhtml+xml') !== false))
	$mobile_browser++;
  if(isset($_SERVER['HTTP_X_WAP_PROFILE']))
	$mobile_browser++;
  if(isset($_SERVER['HTTP_PROFILE']))
	$mobile_browser++;
  $mobile_ua = strtolower(substr($_SERVER['HTTP_USER_AGENT'],0,4));
  $mobile_agents = array(
		'w3c ','acs-','alav','alca','amoi','audi','avan','benq','bird','blac',
		'blaz','brew','cell','cldc','cmd-','dang','doco','eric','hipt','inno',
		'ipaq','java','jigs','kddi','keji','leno','lg-c','lg-d','lg-g','lge-',
		'maui','maxo','midp','mits','mmef','mobi','mot-','moto','mwbp','nec-',
		'newt','noki','oper','palm','pana','pant','phil','play','port','prox',
		'qwap','sage','sams','sany','sch-','sec-','send','seri','sgh-','shar',
		'sie-','siem','smal','smar','sony','sph-','symb','t-mo','teli','tim-',
		'tosh','tsm-','upg1','upsi','vk-v','voda','wap-','wapa','wapi','wapp',
		'wapr','webc','winw','winw','xda','xda-'
		);
  if(in_array($mobile_ua, $mobile_agents))
	$mobile_browser++;
  if(strpos(strtolower($_SERVER['ALL_HTTP']), 'operamini') !== false)
	$mobile_browser++;
  // Pre-final check to reset everything if the user is on Windows
  if(strpos(strtolower($_SERVER['HTTP_USER_AGENT']), 'windows') !== false)
	$mobile_browser=0;
  // But WP7 is also Windows, with a slightly different characteristic
  if(strpos(strtolower($_SERVER['HTTP_USER_AGENT']), 'windows phone') !== false)
	$mobile_browser++;
  if($mobile_browser>0)
	retu