PHP 判断是手机还是电脑在访问

public 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;  
 }