JAX-RS ETag Filter

JAX-RS cache control finally became easy! Add ETags to all your responses and send 304 Not Modified whenever a client sends matching ETags in If-None-Modified headers - with just one annotation!

To get started, get the latest version from jitpack:

https://jitpack.io/#tobilarscheid/jaxrs-etag-filter/

Make sure the entity you are planning to return from your service implements ETagged:

public class Entity implements ETagged {
    public String getETag(){
        /**
        * if you you are reading this you probably know
        * what to consider when generating ETags
        */
    }
}

Then, simply annotate your service Method with @ETag.

@ETag
public Response getMyEntity(){
    Entity e = //do something to get your entity here
    return Response.ok(e).build();
}

The ETag header is automatically added to your Response. If the client sends a request with a If-None-Match header matching your entities ETag, Status Code 304 and no body is returned.

Hints

• All the functionality is only applied if your Response´s status code is 200
• If you don't use class path scanning (hint: you shouldn't), you need to list de.tobiaslarscheid.etag.ETagFilter.class in your RestAppConfig. (Or whereever else you register your resource classes)
• If you want to use Cache-Controlor Expires headers to complete your caching, you should have a look at JAX-RS Cache-Control Filter

License

MIT