ajax and struts 1.2

[faru]

I want to have three level dependent drop down lists using AJAX:
Meaning:
User chooses an option in dropdown 1 from Access database.
this lead to dropdown 2 getting populated as per options avalable related
to the choice made in dropdown 1 from Access database.
similarly when the user chooses some option in dropdown 2 the dropdown 3
gets populated with options related to the choice made in dropdown 2 from
Access database.
The options for all the three drop down lists are available in MySql
database.
Till the user selects any option in dropdown 1, the other two drop down
remain unfilled and blank.

Please advise on how to achieve it and is there any sample code available to
achieve the above using AJAX and struts1.