There's a handy wizard in Eclipse that does this automatically.
1. Right click in the class you wish to modify. Choose "Refactor >
Rename" from the context menu
2. You should check the options 'Update textual occurrences in
comments and strings' and 'Update fully-qualified named in non-java
text files' (maybe restrict to *.xml)
3. ...
4. Profit !
Of course this will not automatically change the Async nor the
interface name, but it will change the servlet declaration in web.xml
Hope that helps,
Salvador
PS: A screenshot of step 2:
http://bayimg.com/image/fapcoaabl.jpg