I have used the struts framework and find it fairly easy to learn. When using the struts framework each page of your site will have the following items.
1) An action which is used is called every time the HTML page is refreshed. The action should populate the data in the form when the page is first loaded and handles interactions between the web UI and the business layer. If you are using the jsp page to modify a mutable java object a copy of the java object should be stored in the form rather than the original so that the original data doesn't get modified unless the user saves the page.
2) The form which is used to transfer data between the action and the jsp page. This object should consist of a set of getter and setters for attributes that need to be accessible to the jsp file. The form also has a method to validate data before it gets persisted.
3) A jsp page which is used to render the final HTML of the page. The jsp page is a hybrid of HTML and special struts tags used to access and manipulate data in the form. Although struts allows users to insert Java code into jsp files you should be very cautious about doing that because it makes your code more difficult to read. Java code inside jsp files is difficult to debug and can not be unit tested. If you find yourself writing more than 4-5 lines of java code inside a jsp file the code should probably be moved to the action.
