public function appendFile($bucket, $object, $file, $position, $options = NULL)
    {
        $this->precheckCommon($bucket, $object, $options);

        OssUtil::throwOssExceptionWithMessageIfEmpty($file, "file path is invalid");
        $file = OssUtil::encodePath($file);
        if (!file_exists($file)) {
            throw new OssException($file . " file does not exist");
        }
        $options[self::OSS_FILE_UPLOAD] = $file;
        $file_size = filesize($options[self::OSS_FILE_UPLOAD]);
        $is_check_md5 = $this->isCheckMD5($options);
        if ($is_check_md5) {
            $content_md5 = base64_encode(md5_file($options[self::OSS_FILE_UPLOAD], true));
            $options[self::OSS_CONTENT_MD5] = $content_md5;
        }
        if (!isset($options[self::OSS_CONTENT_TYPE])) {
            $options[self::OSS_CONTENT_TYPE] = $this->getMimeType($object, $file);
        }

        $options[self::OSS_METHOD] = self::OSS_HTTP_POST;
        $options[self::OSS_BUCKET] = $bucket;
        $options[self::OSS_OBJECT] = $object;
        $options[self::OSS_CONTENT_LENGTH] = $file_size;
        $options[self::OSS_SUB_RESOURCE] = 'append';
        $options[self::OSS_POSITION] = strval($position);

        $response = $this->auth($options);
        $result = new AppendResult($response);
        return $result->getData();
    }