function marketQRCode($data, $errorCorrectionLevel = 'L', $matrixPointSize = 4)
 {
     require_once MARKET_ROOT_DIR . '/redist/phpqrcode/qrlib.php';
     $code = md5($data . '|' . $errorCorrectionLevel . '|' . $matrixPointSize);
     $code_dir = substr($code, 0, 2);
     $filename = MARKET_ROOT_DIR . '/cache/qrcode/' . $code_dir . '/' . md5($data . '|' . $errorCorrectionLevel . '|' . $matrixPointSize) . '.png';
     if (!@is_file($filename)) {
         MARKET_Base::makeDir(dirname($filename));
         QRcode::png($data, $filename, $errorCorrectionLevel, $matrixPointSize, 2);
     }
     return MARKET_WEB_DIR . '/cache/qrcode/' . $code_dir . '/' . basename($filename);
 }