Ajax file uploader with java backend

I need a simple web app that displays a couple of fileds in which a user can select one file (any type) and upload it to a server. The file upload must be done in ajax, so the user can upload one file and while that files is being upload, can chose another file on the other field and start the upload. Nothing fancy on the interface, just a regular form. It will need to display a progress bar during the upload, for each file. User JQuery on the front end and Java/Spring3 on the backend. After the file is uploaded, the field is available again to upload another file. Files should be stored in /tmp on the servers file system