Php PSR-7响应，获取文件mime-type

I've got a $response variable, which implements Psr\Http\Message\ResponseInterface.

It contains info about downloaded file. How can I get mime-type of this file?

Since ResponseInterface extends MessageInterface, you can use the getHeader($name) or getHeaderLine($name) method to retrieve the value of the Content-Type response header. For example...

$mimeType = $response->getHeaderLine('Content-Type');

Note: I used getHeaderLine as it's unlikely the Content-Type header will contain more than one value and this will save you treating the return value as a single-item array.