Example ex12_1 : ContainerResponseFilter and DynamicFeature

ex12_1 implements the @MaxAge and CacheControlFilter example in the section DynamicFeature.

The Server Code

The @MaxAge, CacheControlFilter, and MaxAgeFeature classes were explained pretty well in DynamicFeature, so I’m not going to go into them again here. We applied the @MaxAge annotation to the CustomerResource.getCustomer() method:

   @GET
   @Path("{id}")
   @Produces("application/xml")
   @MaxAge(500)
   public Customer getCustomer(@PathParam("id") int id)
   {
      Customer customer = customerDB.get(id);
      if (customer == null)
      {
         throw new WebApplicationException(Response.Status.NOT_FOUND);
      }
      return customer;
   }

Applying this annotation to this method will cause the CacheControlFilter to be bound to this method when it is executed. The filter will cause a Cache-Control header to be added to the HTTP response with a max age of 500 seconds. Let’s also take a look at how these classes are registered:

@ApplicationPath("/services")
public class ShoppingApplication extends Application
{
   private Set<Object> singletons = new HashSet<Object>();
   private Set<Class<?>> classes = new HashSet<Class<?>>();

   public ShoppingApplication()
   {
      singletons.add(new CustomerResource());
      classes.add(MaxAgeFeature.class);
   }

   @Override
   public Set<Class<?>> getClasses()
   {
      return classes;
   }

   @Override
   public Set<Object> getSingletons()
   {
      return singletons;
   }
}

Notice that we only register the MaxAgeFeature class. This class handles the registration of the CacheControlFilter if the JAX-RS method is annotated with @MaxAge.

The Client Code

The client code hasn’t changed much from other examples. We first start off by creating a Customer on the server. We then do a GET request to get the customer, checking for the Cache-Control header generated by the CacheControlFilter on the server side:

...

      System.out.println("*** GET Created Customer **");
      response = client.target(location).request().get();
      CacheControl cc = CacheControl.valueOf(
                           response.getHeaderString(HttpHeaders.CACHE_CONTROL));
      System.out.println("Max age: " + cc.getMaxAge());

There is nothing really special about this code other than it shows you how to create a CacheControl object from a header string.

Build and Run the Example Program

Perform the following steps:

1. Open a command prompt or shell terminal and change to the ex12_1 directory of the workbook example code.
2. Make sure your PATH is set up to include both the JDK and Maven, as described in Chapter 17.
3. Perform the build and run the example by typing maven install.