Generate GUI for Java-based web application

Currently we have a requirement开发者_StackOverflow wherein we are suppose to generate the GUI of the web based application. User will add / modify XML file, which will be parsed by our application at build time to generate the UI related classes. The application has to be on java platform. However currently we are open for choosing the view technology. It can be JSP or flex something else which fits with java. Do we already have some open source frameworks which does this job?

Apache Cocoon works in that way - you edit XML files which get XSLT-ed into HTML views.

Have you tried GWT? It has a XML based UI Binder which you could use.