public static void downloadFile()
{
Mac mac = new Mac(Settings.AccessKey, Settings.SecretKey);
// 加上过期参数，使用?e=<UnixTimestamp>
// 如果rawUrl中已包含?，则改用&e=<UnixTimestamp>
string rawUrl = "RAW_URL";
string expireAt = "UNIX_TIMESTAMP";
string mid = "?e=";
if(rawUrl.Contains("?"))
{
mid = "&e=";
}
string token = Auth.createDownloadToken(rawUrl + mid + expireAt, mac);
string accUrl = rawUrl + mid + expireAt + "&token=" + token;
// 接下来可以使用accUrl来下载文件
System.Console.WriteLine(accUrl);
}