firefox cuts files, whose name contains spaces, struts application

i am controlling unbroken category (simplified effect understandability) download images struts web application.
it operative glorious each browser nonetheless firefox, cuts names containing spaces. say: file spaces.pdf gets downloaded firefox as: file while chrome, ie7 ie6 downloaded file spaces.pdf.

public category download extends movement {
    private stationary final int buffer_size = 4096;    

    open actionforward execute(actionmapping mapping,
        actionform     form,
        httpservletrequest request,
        httpservletresponse response) throws difference {
        twine filename = "file spaces.pdf";
        record file =  ... // non-static containing file;
        response.setstatus(httpservletresponse.sc_ok);
        response.setcontenttype(getmimetype(request, file));
        response.setheader("content-type", getmimetype(request, file));
        response.setheader("content-disposition","attachment; filename="+ filename);
        inputstream = new fileinputstream(file); 
        sendfile(is, response);
        relapse null;
   }  

   stable twine getmimetype(httpservletrequest request, record file) {
        servletcontext concentration = super.servlet.getservletcontext();
        relapse application.getmimetype(file.getname());
   }

   stable vacant sendfile(inputstream is, httpservletresponse response) throws ioexception {
       bufferedinputstream = null;
       try {
            int count;
            byte[] aegis = new byte[buffer_size];
            = new bufferedinputstream(is);
            servletoutputstream out = response.getoutputstream();
            while(-1 != (count = in.read(buffer)))
                out.write(buffer, 0, count);
            out.flush();            
       } locate (ioexception ioe) { 
            system.err.println("ioexception download::sendfile"); 
            ioe.printstacktrace();
       } finally {
            (in != null) {
                try { 
                   in.close(); 
                } locate (ioexception ioe) { ioe.printstacktrace(); }
            }   
       }
    }
}

does anyone know going here? note i am controlling firefox 3.0.3 underneath windows vista.