(PECL pecl_http >= 0.10.0)
HttpResponse::setContentDisposition — Set content disposition
Set the Content-Disposition. The Content-Disposition header is very useful if the data actually being sent came from a file or something similar, that should be "saved" by the client/user (i.e. by the browser's "Save as..." popup window).
the file name the "Save as..." dialog should display
if set to true and the user agent knows how to handle the content type, it will probably not cause the popup window to be shown
如果成功则返回 TRUE，失败则返回 FALSE。