If you're using tomcat, you can try their utf8 encoding filter (add it to your web.xml of course). Their filter is called org.apache.catalina.filters.SetCharacterEncodingFilter, or if you don't want to depend on 3rd party then you can peek at their source code and write your own, it's not very complicated.
See also
http://wiki.apache.org/tomcat/FAQ/CharacterEncoding
