You should check whether Restlet is compliant with android,
not just from server side code, but also from client side code (respectively).
This means for example that every JAR that Restlet framework depends on has to contain code that is compliant with Android.
An alternative approach would be to run a simple HTTP server on your device, for example the following nano http server I read about.
Another interesting project you should check is jetty for android which will hopefully give you support for servlet API as well.
Yes, you will have to spend some time on developing mapping requests and building resource handling logic, but that task is not that difficult:
A. You already have Android code for JSON processing -
For example, look here
B. Using the Java URL object you can analyze the URL of the request and understand which resource you should handle (i.e - add resource to collection, fetch collections, etc).
C. After performing the CRUD operation (i.e - store your resource in some SQLIte table), you can send back a response, and once again, composing JSON if needed is easy.