Filters and Interceptors - RESTful Java with JAX-RS 2.0 - page 182

unauthenticated users executing any of your JAX-RS components. So, if you have a custom
authentication filter, you probably want that filter to be executed first. Another example is
the combination of our GZIP encoding example with a separate WriterInterceptor that
encrypts the message body. You probably don't want to encrypt a GZIP-encoded representa-
tion. Instead you'll want to GZIP-encode an encrypted representation. So ordering is import-
ant.

In JAX-RS, filters and interceptors are assigned a numeric priority either through the @Pri-
ority annotation or via a programmatic interface defined by Configurable . The JAX-RS
runtime sorts filters and interceptors based on this numeric priority. Smaller numbers are first
in the chain:

package package javax . annotation ;

public public @interface Priority {

int

int value ();

}

The @Priority annotation is actually reused from the injection framework that comes with
JDK 7. This annotation would be used as follows:

import import javax.annotation.Priority javax.annotation.Priority ;

import import javax.ws.rs.Priorities javax.ws.rs.Priorities ;

@Provider
@PreMatching
@Priority ( Priorities . AUTHENTICATION )
public public class class BearerTokenFilter BearerTokenFilter implements implements ContainerRequestFilter {

...
}

The @Priority annotation can take any numeric value you wish. The Priorities class spe-
cifies some common constants that you can use when applying the @Priority annotation:

package package javax . ws . rs ;

public public final final class class Priorities Priorities {

private private Priorities () {

// prevents construction

}

/**
* Security authentication filter/interceptor priority.
*/