Dynamic Provider Registration in JAX-RS

The DynamicFeature class in JAX-RS (2.0) allows you to register providers:

• Dynamically i.e. without any pre-defined binding strategy (e.g. annotations).
• Based on criteria i.e. to help decide which provider to bind to which JAX-RS resource(s).

The JAX-RS implementation detects and executes the DynamicFeature implementations at deployment time

Here is an example where we instruct the JAX-RS runtime to dynamically bind the AuthenticationFilter (a JAX-RS post construct filter) to be applied when a PUT is invoked on UserResource (which is a JAX-RS resource class):

@Provider
public class DynamicFilter implements DynamicFeature {
  @Override
  public void configure(ResourceInfo resInfo, FeatureContext ctx) {
    if (UserResource.class.equals(resInfo.getResourceClass()) &&
      resInfo.getResourceMethod().getName().contains("PUT")) {
      ctx.register(AuthenticationFilter.class);
    }
  }
}

Criteria-Based

Criteria are provided by ResourceInfo, and they're based on two attributes:

• The resource class
• The resource method

Dynamic

Dynamic registration is achieved using FeatureContext, whose register method can be used to bind the provider.

Note

• @Provider is needed for automatic discovery by the JAX-RS runtime.
• Applicable for: filters, interceptors and  any Feature
• In case of filters, the following applicability criteria apply
  • Post matching (@PreMatching filters excluded).
  • Server side filters i.e. ClientRequestFilter and ClientResponseFilter cannot be registered using this method.
• Once used, it overrides other bindings (static or using @NameBinding).