Example: StringParamUnmarshaller interface
Here's an example of formatting a java.util.Date based @PathParam public class StringParamUnmarshallerTest extends BaseResourceTest { @Retention(RetentionPolicy.RUNTIME) @StringParameterUnmarshallerBinder(DateFormatter.class) public @interface DateFormat { String value(); } public static class DateFormatter implements StringParameterUnmarshaller { private SimpleDateFormat formatter; public void setAnnotations(Annotation[] annotations) { DateFormat format = FindAnnotation.findAnnotation(annotations, DateFormat.class); formatter = new SimpleDateFormat(format.value()); } public Date fromString(String str) { try { return formatter.parse(str); } catch (ParseException e) { throw new RuntimeException(e); } } } @Path("/datetest") public static class Service { @GET @Produces("text/plain") @Path("/{date}") public String get(@PathParam("date") @DateFormat("MM-dd-yyyy") Date date) { System.out.println(date); Calendar c = Calendar.getInstance(); c.setTime(date); Assert.assertEquals(3, c.get(Calendar.MONTH)); Assert.assertEquals(23, c.get(Calendar.DAY_OF_MONTH)); Assert.assertEquals(1977, c.get(Calendar.YEAR)); return date.toString(); } } @BeforeClass public static void setup() throws Exception { addPerRequestResource(Service.class); } @Test public void testMe() throws Exception { ClientRequest request = new ClientRequest(generateURL("/datetest/04-23-1977")); System.out.println(request.getTarget(String.class)); } } In the example a new annotation is defined called @DateFormat. This annotation class is annotated with the meta-annotation StringParameterUnmarshallerBinder with a reference to the DateFormmater classes. The Service.get() method has a @PathParam parameter that is also annotated with @DateFormat. The application of @DateFormat triggers the binding of the DateFormatter. The DateFormatter will now be run to unmarshal the path parameter into the date paramter of the get() method.