Change AbstractDefaultAjaxBehavior to allow multipart

[Tobias Soloschenko]

Hi all,

I am currently writing an implementation for a modern file upload based 
on dropzone.js:

https://github.com/l0rdn1kk0n/wicket-bootstrap/issues/371

I am using AbstractDefaultAjaxBehavior to send the files back to the 
server. At this place I need to adjust the AbstractDefaultAjaxBehavior 
to enable it for multipart:

        @Override
        protected AjaxRequestAttributes getAttributes()
        {
            AjaxRequestAttributes attributes = super.getAttributes();
            attributes.setMultipart(true);
            return attributes;
        }

Currently getAttributes() is set to final and I have no chance to change 
the AjaxRequestAttributes anyhow - so my suggestion would be to add a 
protected method which is called within getAttributes() so that it is 
possible to change the AjaxRequestAttributes.

An example implementation in the response method of the 
AbstractDefaultAjaxBehavior would be:

                    ServletWebRequest webRequest = 
(ServletWebRequest)getRequest();
                    MultipartServletWebRequest multiPartRequest = 
webRequest.newMultipartWebRequest(
                        Bytes.bytes(5000000), "ignored");
                    multiPartRequest.parseFileParts();
                    Map<String, List<FileItem>> files = 
multiPartRequest.getFiles();
                    System.out.println(files);

I checked it already with a demo file and the log result was:

{file=[name=dropzone.js, 
StoreLocation=/var/folders/jh/dw7vk3rs1fbf5gyms4v9k85r0000gn/T/upload_9a1ae025_411f_4e82_8f04_70dc9a7e0a79_79336009.tmp, 
size=63014bytes, isFormField=false, FieldName=file]}

What do you think of adding a method to change the AjaxRequestAttributes 
for AbstractDefaultAjaxBehavior?

kind regards

Tobias