fileupload 404

Hello there.I'm writing a web program using java, ckeditor and nginx. Everything is work ok without nginx's reverse proxy, but I need nginx to load static files, and the problems is coming. This is the way I init ckeditor:

<textarea name="editor1" id="editor1"></textarea>

CKEDITOR.replace('editor1', {
        height: 400,
        filebrowserUploadUrl: "ckeditorupload.htm"
    });

And the nginx config about proxy_pass :

upstream glassfish {
    server 127.0.0.1:8080;
}

server {
    listen       9000;
    server_name  localhost;

    location /web/ {
        proxy_pass http://glassfish;
    }

    location /web/res/ {
    alias /Users/****/Documents/****/;
    }
}

The function I want is :

"localhost:9000/web/res/****.jpg" -> "/Users/****/Documents/****/****.jpg"
"localhost:9000/web/****" -> "localhost:8080/web/****"

So, in this case, when the upload button clicked, a request with url "localhost:9000/web/ckeditorupload.htm" should post to "localhost:8080/web/ckeditorupload.htm", which it didn't, and I got 404 error by nginx. However, if I send request use command line with code "$.ajax({url:"ckeditorupload.htm"});" that will be worked. I don't known what's wrong with the request send by ckeditor and I don't known how to debug it.(BTW, show me a way to log the real url proxy_pass by nginx, please.)

It's the problem cause by domain? webroot? Help, please. Thank you very much in advance!