jsp dynamic gui

Question

Hi, i am asking myself if it is possible to somehow create a dynamic gui in jsp. So that i could have something like a dropdown menue for the country and based on what i have selected in that window a dropdown menue for cities, without reloading the jsp page. Or, in a dialog with multiple input lines, to be able to add an additional line with a button, again without reloading the whole page. In the first case the cities information would be in a database, in the second the information provided would be stored at the end in a database, so i cant just use java script (and don't really want to).

Answer 1

To update the page without posting back the whole page, the browser would use ajax. Using a database does not eliminate ajax. Ajax calls server code that digs your data out of the database.

Regardless, to do what you want, without writing your own javascript, look at GWT (Google Web Toolkit). You right ajax applications in Java that generates the javascript for you.

Answer 2

At a minimum, you would need to utilize JavaScript to implement what you want. Most would implement it the way Tim describes in his first paragraph.

Set up two .JSP's: The first contains your main form with the country drop-down menu. Some JavaScript on the first .JSP triggers an AJAX request to a second .JSP. The second .JSP accepts a country-ID parameter and uses a servlet to query your DB for a list of cities, then renders that data. Once the request returns, the JavaScript in your first .JSP inserts the list of cities into a new drop-down menu.

This may seem complex, but several JavaScript libraries exist to assist you with this task. Look into jQuery or Dojo.