function ismobile() {
 // 如果有HTTP_X_WAP_PROFILE则一定是移动设备
 if (isset ($_SERVER['HTTP_X_WAP_PROFILE']))
 return true;
 
 //此条摘自TPM智能切换模板引擎，适合TPM开发
 if(isset ($_SERVER['HTTP_CLIENT']) &&'PhoneClient'==$_SERVER['HTTP_CLIENT'])
 return true;
 //如果via信息含有wap则一定是移动设备,部分服务商会屏蔽该信息
 if (isset ($_SERVER['HTTP_VIA']))
 //找不到为flase,否则为true
 return stristr($_SERVER['HTTP_VIA'], 'wap') ? true : false;
 //判断手机发送的客户端标志,兼容性有待提高
 if (isset ($_SERVER['HTTP_USER_AGENT'])) {
 $clientkeywords = array(
  'nokia','sony','ericsson','mot','samsung','htc','sgh','lg','sharp','sie-','philips','panasonic','alcatel','lenovo','iphone','ipod','blackberry','meizu','android','netfront','symbian','ucweb','windowsce','palm','operamini','operamobi','openwave','nexusone','cldc','midp','wap','mobile'
 );
 //从HTTP_USER_AGENT中查找手机浏览器的关键字
 if (preg_match("/(" . implode('|', $clientkeywords) . ")/i", strtolower($_SERVER['HTTP_USER_AGENT']))) {
  return true;
 }
 }
 //协议法，因为有可能不准确，放到最后判断
 if (isset ($_SERVER['HTTP_ACCEPT'])) {
 // 如果只支持wml并且不支持html那一定是移动设备
 // 如果支持wml和html但是wml在html之前则是移动设备
 if ((strpos($_SERVER['HTTP_ACCEPT'], 'vnd.wap.wml') !== false) && (strpos($_SERVER['HTTP_ACCEPT'], 'text/html') === false || (strpos($_SERVER['HTTP_ACCEPT'], 'vnd.wap.wml') < strpos($_SERVER['HTTP_ACCEPT'], 'text/html')))) {
  return true;
 }
 }
 return false;
 }

Class CommonAction extends Action{
 Public function _initialize(){
 //移动设备浏览，则切换模板
 if (ismobile()) {
  //设置默认默认主题为 Mobile
  C('DEFAULT_THEME','Mobile');
 }
 //............你的更多代码.......
 }
 }