public function parseFromXml($strXml)
    {
        $xml = simplexml_load_string($strXml);
        if (!isset($xml->CORSRule)) return;
        foreach ($xml->CORSRule as $rule) {
            $corsRule = new CorsRule();
            foreach ($rule as $key => $value) {
                if ($key === self::OSS_CORS_ALLOWED_HEADER) {
                    $corsRule->addAllowedHeader(strval($value));
                } elseif ($key === self::OSS_CORS_ALLOWED_METHOD) {
                    $corsRule->addAllowedMethod(strval($value));
                } elseif ($key === self::OSS_CORS_ALLOWED_ORIGIN) {
                    $corsRule->addAllowedOrigin(strval($value));
                } elseif ($key === self::OSS_CORS_EXPOSE_HEADER) {
                    $corsRule->addExposeHeader(strval($value));
                } elseif ($key === self::OSS_CORS_MAX_AGE_SECONDS) {
                    $corsRule->setMaxAgeSeconds(strval($value));
                }
            }
            $this->addRule($corsRule);
        }
        return;
    }