Adding i18n using subfolder technique and a Proxy

Question

I've a webapp running on context "/" and I want now to internationalize it using a subfolder technique.

I want the same site previously hosted under

http://www.mysite.com/

now to serve different languages content under the urls

http://www.mysite.com/en/<br>
http://www.mysite.com/fr/<br>
http://www.mysite.com/de/<br>

I'm thinking in adding an Apache Proxy in front of Tomcat to leave my webapp untouched.

Let's say the app is already supporting i18n based on a cookie present in the request that identifies the language.

With Apache Proxy and Rewrite rule I could strip out the language from the request and add this cookie with the extracted language.

I need then Apache to convert the redirects coming from Tomcat by adding the specific language (passProxyReverse ?)

I need also that the HTML produced by my app is somehow parsed so that links that look like http://www.mysite.com/folder/contact.html are modified into http://www.mysite.com/de/folder/contact.html (mod_proxy_html ?)

I thought about other solutions like deploying the same webapp under different contexts and share sessions through memcache.. or to manage this language subfolder separation directly with some Filter in the webapp and some custom JSTL etc.

All solutions seems a bit too complex.

What I'm trying to achieve is to have a subfolder technique for SEO reasons and to make my webapp not too much aware of this.

I don't understand if I'm complicating it too much..
Are there better/simplier ways to achieve what I need?