Filters and Interceptors - RESTful Java with JAX-RS 2.0 - page 185

To illustrate how you'd use DynamicFeature , let's expand on the CacheControlFilter re-
sponse filter we wrote earlier in this chapter. The previous incarnation of this class would set
the same Cache-Control header value for each and every HTTP request. Let's modify this
filter and create a custom annotation called @MaxAge that will allow you to set the max-age
of the Cache-Control header per JAX-RS method:

package package com . commerce . MaxAge ;

@Target ( ElementType . METHOD )
@Retention ( RetentionPolicy . RUNTIME )
public public @interface MaxAge {

int int value ();

}

The modification of the filter looks like this:

import import javax.ws.rs.container.ContainerResponseFilter javax.ws.rs.container.ContainerResponseFilter ;

import import javax.ws.rs.container.ContainerRequestContext javax.ws.rs.container.ContainerRequestContext ;

import import javax.ws.rs.container.ContainerResponseContext javax.ws.rs.container.ContainerResponseContext ;

import import javax.ws.rs.core.CacheControl javax.ws.rs.core.CacheControl ;

public public class class CacheControlFilter CacheControlFilter implements implements ContainerResponseFilter {

private private int int maxAge ;

public public CacheControlFilter ( int int maxAge ) {

this this . maxAge = maxAge ;

}

public public void void filter ( ContainerRequestContext req , ContainerResponseContext res )

throws throws IOException

{

iif ( req . getMethod (). equals ( "GET" )) {
CacheControl cc = new

new CacheControl ();

cc . setMaxAge ( this this . maxAge );

res . getHeaders (). add ( "Cache-Control" , cc );

}

}

}

The CacheControlFilter has a new constructor that has a max age parameter. We'll use
this max age to set the Cache-Control header on the response. Notice that we do not annot-
ate CacheControlFilter with @Provider . Removing @Provider will prevent this filter
from being picked up on a scan when we deploy our JAX-RS application. Our Dynam-
icFeature implementation is going to be responsible for creating and registering this filter: