CopyFile 复制文件.

Download 下载文件.

DownloadTo 下载到目录.

IsDir 检查是否目录.

IsFile 文件是否存在.

Random takes a parameter (int) and returns random slice of byte ex: var randomstrbytes []byte; randomstrbytes = utils.Random(32).

RandomString accepts a number(10 for example) and returns a random string using simple but fairly safe random algorithm.

Stringify json 序列化.

UriToPath File URI to Path function.