rfc2616

The Content-Length entity-header field indicates the size of the entity-body,
in decimal number of OCTETs, sent to the recipient or, in the case of the HEAD
method, the size of the entity-body that would have been sent had the request
been a GET. 

内容类型是什么并不重要。

It doesn't matter what the content-type is.

在发布在下方的扩展程序。