PHP 过滤特殊字符(微信qq)

/**
 * 过滤特殊字符(微信qq)
 *
 * @param unknown $str            
 */
function filterStr($str)
{
    if ($str) {
        $name = $str;
        $name = preg_replace_callback('/\xEE[\x80-\xBF][\x80-\xBF]|\xEF[\x81-\x83][\x80-\xBF]/', function ($matches)
        {
            return '';
        }, $name);
        $name = preg_replace_callback('/xE0[x80-x9F][x80-xBF]‘.‘|xED[xA0-xBF][x80-xBF]/S', function ($matches)
        {
            return '';
        }, $name);
        // 汉字不编码
        $name = json_encode($name);
        $name = preg_replace_callback("/\\\ud[0-9a-f]{3}/i", function ($matches)
        {
            return '';
        }, $name);
        if (! empty($name)) {
            $name = json_decode($name);
            return $name;
        } else {
            return '';
        }
    } else {
        return '';
    }
}