SceneBuilder allows you to create form in JavaFX. The SceneBuilder UI definitions are in FXML and CSS - which are just text files. As an FXML and CSS files are just strings, you could store them in a database if you wised.
You may download SceneBuilder from here:
http://gluonhq.com/products/scene-builder/
FXML is just a UI definition language so it's scope does not encompass other aspects often found in form fill applications (such as validation).
FXForm2 is a form generator which generates a form layout and validations from
Java code with bean annotations, where the form design and layout can be provided as input in an FXML document rather than being auto generated from a bean:
http://dooapp.github.io/FXForm2/
Makery provide a nice tutorial on developing a JavaFX form-fill application based on FXML created in SceneBuilder:
http://code.makery.ch/library/javafx-8-tutorial/