I'm just getting acquainted with implementing REST web services in Java using JAX-RS and I ran into the following problem. One of my resource classes requires access to a storage backend, which is abstracted away behind a StorageEngine interface. I would like to inject the current StorageEngine instance into the resource class serving the REST requests and I thought a nice way of doing this would be by using the @Context annotation and an appropriate ContextResolver class. This is what I have so far:

In MyResource.java:

class MyResource {
    @Context StorageEngine storage;
    [...]
}

In StorageEngineProvider.java:

@Provider
class StorageEngineProvider implements ContextResolver<StorageEngine> {
    private StorageEngine storage = new InMemoryStorageEngine();

    public StorageEngine getContext(Class<?> type) {
        if (type.equals(StorageEngine.class))
            return storage;
        return null;
    }
}

I'm using com.sun.jersey.api.core.PackagesResourceConfig to discover the providers and the resource classes automatically, and according to the logs, it picks up the StorageEngineProvider class nicely (timestamps and unnecessary stuff left out intentionally):

INFO: Root resource classes found:
    class MyResource
INFO: Provider classes found:
    class StorageEngineProvider

However, the value of storage in my resource class is always null - neither the constructor of StorageEngineProvider nor its getContext method is called by Jersey, ever. What am I doing wrong here?