hunchentoot下如何post文件？

加了一个handler test8
(HUNCHENTOOT:DEFINE-EASY-HANDLER (TEST8 :URI "/test8")
(file)
(SETF (HUNCHENTOOT:CONTENT-TYPE*) "text/html")
(HUNCHENTOOT:POST-PARAMETER "file")
(format nil "~A~A~A"
(<head-id "3745528340")
(<left-bar "BHa2R")
(<right-bar (concatenate 'string "<pre>" file "</pre>"))))
上传页面html
<form action=\"/test8\" method=\"post\" \">
<input type=\"file\" /><input type=\"submit\" /><br>
</form>
然后上传文件

然后如预期调至test8,但啥也没发生

定义的网页根目录下也没发现被上传文件
不过stackoverflow上有人问过
https://stackoverflow.com/questions/15249921/how-to-handle-multiple-file-upload-in-hunchentoot#15258756
不太清楚具体咋弄