没有精确文件类型"之类的东西.二进制数据是二进制数据.

There's no such thing as "exact file type". Binary data is binary data.

如果您在类似POSIX的系统上运行，则可以使用file命令来猜测文件类型.我认为这不会给您提供MIME类型.

If you're running on a POSIX-like system, you can use the file command to guess the file type. I don't think this gives you a MIME type.

如果您的服务器运行的是Apache，则可以使用mod_mime_magic进行猜测.

If your server is running Apache, then you can use mod_mime_magic to make a guess.

如果您使用的是PHP，则可以安装 fileinfo 扩展名.

If you're using PHP, you can install the fileinfo extension.