Php determines whether it is a mobile device, php determines the device

Php determines whether it is a mobile device, php determines the device
<?phpfunction isMobile(){     // If HTTP_X_WAP_PROFILE exists, it must be a mobile device.    if (isset ($_SERVER['HTTP_X_WAP_PROFILE']))    {        return true;    }     // If the via information contains wap, it must be a mobile device. Some service providers will block this information.    if (isset ($_SERVER['HTTP_VIA']))    {         // Flase cannot be found; otherwise, true        return stristr($_SERVER['HTTP_VIA'], "wap") ? true : false;    }     // Identify the client flag sent by the mobile phone. The compatibility needs to be improved.    if (isset ($_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'            );         // Search for the keyword of the mobile browser from HTTP_USER_AGENT        if (preg_match("/(" . implode('|', $clientkeywords) . ")/i", strtolower($_SERVER['HTTP_USER_AGENT'])))        {            return true;        }     }     // Resolution, which may be inaccurate and placed in the final judgment    if (isset ($_SERVER['HTTP_ACCEPT']))    {         // If only wml is supported and html is not supported, it must be a mobile device.        // If wml and html are supported, but wml is a mobile device before html        if ((strpos($_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;} ?>